Reserve . Division of Agricultural Sciences UNIVERSITY OF CALIFORNIA a ■ IRRIGATED PASTURE FOR STEERS AND LAMBS California Reserve ij&MJ''^"'"'- ^,._ ? &f,~ ^, J.L.HULL ff S J. H. MEYER is •§ jpJB CONTENTS The Findings 3 General Management and Procedures 4 Grazing Management 6 Type of Forage 6 Reasons for Grazing Mixtures 8 Type of Animal 9 Daily Ration vs. Weekly Rotation 9 Recovery Interval 9 Stocking Rate 10 Continuous vs. Rotational Grazing Systems 15 Grazing Behavior 17 Day in the Field 17 Selective Grazing 18 Stocking Rate . 22 Soilage 22 Soilage vs. Haying or Pasturing 23 Soilage for Sheep 23 Soilage for Cattle 24 Supplementation 25 Supplementation of Alfalfa 26 Supplementation of Alfalfa Soilage and Hay 26 Amount of Supplement to Feed with Alfalfa 28 Limited Supplementation of Irrigated Pasture 29 "Full Feeding" on Pasture 29 Energy Requirements for Grazing 30 Energy Requirements Compared 31 Behavior 31 Compensatory Growth 32 Wintering and Pasturing for Compensatory Growth 32 Compensatory Growth in the Feedlot 33 Reasons for Compensatory Growth 36 Role of Irrigated Pasture 36 Irrigated Pasture as an Energy Source 36 Irrigated Pasture as a Protein Source 39 References 40 DECEMBER, 1967 THE AUTHORS }. L. Hull is Associate Specialist, Department of Animal Science, Davis. J. H. Meyer is Professor of Animal Science and Animal Scientist in the Experiment Station, Davis. IRRIGATED PASTURE FOR STEERS AND LAMBS THE FINDINGS This bulletin describes a series of animal experiments, conducted at Davis, to establish principles and methods for best utilization of irrigated pasture, emphasizing those fac- tors that may be controlled by the pasture operator. The following is a summary of the findings and some recommendations. Grazing management. Forage yield varies with species, variety and season. A simple, highly productive, palatable mixture of grasses and legumes should be grown. The pas- ture operator can take advantage of seasonal growth characteristics, soil conditions, re- covery after grazing, bloat potential and stocking rate of a mixture. Sheep, because of their superior selective grazing ability, will fatten to an acceptable slaughter grade on good irrigated pasture. This is not true for cattle. Under conditions of strip, daily, or weekly rotational grazing, the most beef per acre is achieved by a weekly movement of cattle to another field where the forage is growing rapidly and the stocking rate is slightly higher than that which gives optimum individual animal performance. Under conditions of one-field continuous-grazing the most beef per acre is realized when cattle are grazed for the optimum individual performance. At the present time, continuous grazing is not recommended over rotational grazing because such factors as water use and soil com- paction have not been clarified. Grazing behavior. The time an animal will spend grazing and ruminating increases as feed available decreases. The TDN content of the diet that sheep select on the fifth day in a field is the same as that selected on the second day. Sheep, being more selective, choose a more nutritious diet than cattle, especially when they are grazing a tall crop such as alfalfa. Increased stocking rate increase grazing time up to a point (10 hours per day) and then remain constant even if available forage decreases below animal needs. Grazing behavior can determine what type of animal and what endproduct is to be selected. Soilage. The greatest beef production per acre from forage results from soilage fol- lowed by haying and then pasturing the same crop. The average increase in meat yield per acre has been 30 percent over other methods of harvesting the same crop. Soilage should not be fed as a fattening diet to sheep because, if forced to eat all the forage plant, they are unable to select a highly nutritious ration. Soilage for cattle produces lower gains than grazing but more beef per acre because of increased food intake from a soilage diet. Soilage can produce 1,000 pounds of beef or more per acre. Supplementation. An additional source of energy, along with a forage diet, is needed to produce an acceptable slaughter steer in a reasonable time period. Continuous supplementation of alfalfa soilage is more satisfactory than supplementation during only the last half of the feeding period, or none at all. Concentrates should be fed, along with soilage, at the rate of 0.5 pounds per 100 pounds body weight to increase dressing percentage and carcass grades to a satisfactory degree. This amount of concentrate sup- plementation may or may not increase daily gains. Limited supplementation for animals grazing irrigated pasture does not give a satisfactory increase in carcass quality. Feeding free choice, barley or milo, to steers grazing high-quality irrigated pasture at double the normal stocking rate is a satisfactory method of obtaining an acceptable slaughter ani- mal in a reasonable feeding period. Energy requirements for grazing. These studies did not show that increased digestible energy or increased maintenance requirements are necessary for grazing animals. 1 Received for publication March 13, 1967. [3] Compensatory growth. A growth rate greater than normal in animals of the same chronological age can be obtained by cattle on irrigated pasture following a low-energy wintering ration. This increased growth rate also occurs in the feedlot following pastur- ing if stocking rate on pasture is severe enough to limit rate of gain. The length of time and the amount of energy needed above maintenance will determine when to take advantage of compensatory growth. Compensatory growth occurs because of increased feed capacity and increased efficiency of energy utilization. The role of irrigated pasture. Irrigated pasture is a good growing ration but will not produce "fat" cattle. As a sole source of energy it is expensive in relation to feedlot fat- tening, but has the advantage of enabling the pasture operator to influence compensa- tory growth. As a protein source it is very economical especially when used as a protein, vitamin, and mineral source when free choice feeding grain. The varying growth rates that can be obtained when using irrigated pastures can have a definite effect on the eco- nomics of producing and fattening beef cattle. F ■\ Irrigated pastures have become an im- portant factor in land utilization in Cali- fornia. They provide not only a significant role in the economy of many areas but also provide an important part of the forage for California's meat industry. These pas- tures have helped to diversify and balance feed production as well as to conserve and improve the soil on many farms. Sound management is required to meet the challenging problems of irrigated pas- tures. Management must utilize all that is known and must put into effect quickly new research developments. Considerable progress has been made from available in- formation about the necessity for proper land grading allowing adequate slope, ir- rigation requirements in both amount and frequency of application, advantages and limitations of individual species, formula- tion of suitable mixtures, weed control, and application of commercial fertilizers (Peterson et ah, 1959; Martin et al., 1965). GENERAL MANAGEMENT AND PROCEDURES The studies reported were conducted at the University of California at Davis (fig- ure 1). The grazing trials were conducted during the months of May through Sep- tember over a period of eleven years (1954- 1965). A uniform field planted initially to birdsfoot trefoil and orchardgrass (Lotus corniculatus, narrow leaf and Dactylis glo- merata var. Akaroa) was used for these studies. Two years later ladino clover (Tri- folium repens var. latum) was seeded into the existing pasture sod to increase the proportion of legumes because the number of trefoil plants had been drastically re- duced. At the end of the 1962 grazing sea- son, the pastures were again overseeded with orchardgrass and ladino clover and strawberry clover and ryegrass (Trifolium fragiferum var. Salina and Lolium perene). The forages were produced on irrigated fields. Rain was not a factor in maintain- ing a strict pasture rotation, producing high-quality hay or inhibiting the soilage operations [average annual rainfall, May through September 1.0 in.; average maxi- mum temperature 90 °F and average mini- mum temperature 51 °F.]. Pasture irriga- tion was conducted so as to avoid plant moisture stress. The irrigation water was applied by flooding, using the border method. In general, 30 units of nitrogen were applied per month to the fields after the first flush of spring growth was re- [4] 1000' -« Road •- IRRIGATED PASTURE o c c o O -H •H 4-1 ■U Cfl CJ GO 0) T-l u u o o 16.0 Acres Irrigation borders 25' O.C. Stock water Con als Fig. 1. General field layout for irrigated pasture studies. Fencing varied from trial to trial. Usually fences were 25 feet apart, placed upon the irrigation borders. In this case each field was 0.4 acre. When larger fields were necessary, four to six irrigation checks were placed into one field with the fencing again upon the irrigation borders. moved, except during the last two years of the grazing trials when no fertilizer was used. When alfalfa (Medicago Saliva var. Cal- verde) was grazed or harvested it was from an adjoining field and was watered monthly. Before the start of the experiments, the first cutting of forage from each field was harvested and not used for the experiment. This was done to obtain the prescribed number of days regrowth on a field before the cattle were allowed to graze. The fields were again clipped the day the animals were rotated to another pasture. All chop- ping or clipping was performed by use of a flail-type forage harvester. The above was true for all years except the last two when no chopping or clipping was performed. When sheep were used, they were mixed, good-choice crossbred western ewe and wether feeder lambs weighing approxi- mately 70-80 pounds at the start of the studies. Before being allotted at random into lots of 20 head each, they were in- dividually identified, treated for internal parasites, vaccinated for Blue tongue and contagious ecthyma (sore mouth). The beef animals used were yearling good-choice feeder steers usually weighing 550 to 650 pounds at the start of the trials. The ani- mals were individually identified (number branded), vaccinated for infectious bovine rhinotracheitis (IBR), leptospirosis and treated for internal parasites when neces- sary. After an initial adjustment period each year of from three to six weeks, the steers were allotted at random, usually ten head per treatment, to the respective ex- perimental lots. During the course of the [5] experiment all animals were weighed every 28 days after an overnight stand without feed or water. When digestibility and food intake were determined, each lot contained three ani- mals that had previously been trained for fecal collection purposes. The digestibility and feed intake was measured at three ap- proximately equal intervals during each experiment. These determinations were made by administering a 20-gram capsule of chromium oxide orally at 7:00 a.m. daily during a preliminary period of seven days, and continuing for a six-to seven-day col- lection period during which grab samples of feces were collected from the rectum twice daily (7:00 a.m. and 5:00 p.m.). The digestibility and food intake was then de- termined in the laboratory as proposed by Reid et al. (1952) and Lofgreen et al. (1956). Available forage was measured by the clipping technique. Before the animals entered a pasture, 5 to 10 areas of 18 square feet each were clipped at random, 2 inches high. Grab samples were taken from these clipped areas for dry matter and species determinations and others composited for chemical analysis. Because during the lab- oratory analyses a large percentage of silica was found in the forage samples, all results were calculated on a silica-free basis. The comparative slaughter technique was used for determining main differences between treatments. For use of this slaugh- ter technique, representative steers or sheep were slaughtered before the start of the experiment and at the end of the study or, in some trials, at the end of each period. Carcass data were then obtained on these animals. Specific gravity as described by Garrett et al. (1959) and Meyer et al. (1961) was used to estimate body composition. Corrected carcass weights and empty body weights were estimated by the methods proposed by Meyer et al. (1961) and by Lof- green et al. (1962), respectively. Energy gained by the animals during the experi- ments was calculated by comparing initial and final carcass composition. The data were analyzed for variance and covariance, and Duncan's multiple range test (1955) was used to determine differences between treatments. GRAZING MANAGEMENT Management must consider not only the requirements of the plants but also of the animals and their interrelationships. One important aspect of maximum production from forage is the method selected for utili- zation of that forage by animals. Since the beginning of agriculture, pasturing has predominated. Haying was developed to serve the forage shortage caused by the win- ter season. Soiling was first useful where labor was inexpensive and land intensively farmed. Today, the development of labor- saving machines — the forage harvester and self-unloading wagon — revived the practice of soiling. Except for the commercial feed- lot operator, who buys all of his feed, the beef producer has a feed supply that he must market by converting it to meat. The kind, quality, and quantity of feed supply, as well as the time of year it is available, determine the method of utilization and numbers of animals he should have to real- ize the greatest potential gain. It is, there- fore, a constantly pressing problem to find ways of increasing efficiency of livestock operations when returns to the farmer per unit are steady or falling, and production costs are high. An irrigated pasture is an irrigated area with a satisfactory stand of seeded forage plants suitable for grazing by livestock. It may occasionally be mowed for hay, soilage (green chop), or to reduce weeds or coarse clumps; in general, how- ever, it is used to produce the most pounds of meat per acre by grazing livestock. TYPE OF FORAGE Yields per acre of irrigated pasture vary considerably from month to month (figure 2) and from year to year. Furthermore, to- tal yields for the year varies widely from farm to farm, depending on differences in soil, climate, cultural practices, species grown, and grazing management. Pastur- [6] FEB MARCH APRIL MAY JUNE JULY AUG SEPT OCT Fig. 2. Average seasonal forage growth for four different irrigated pasture mixtures when each was harvested at intervals of five weeks over the three-year period / 1949-1951 (Peterson and Hagan, 1953). Table 1 EFFECT OF CUTTING FREQUENCY UPON THE BOTANICAL COMPOSITION OF FOUR IRRIGATED PASTURE MIXTURES AS DETERMINED BY HAND SEPARATIONS MADE IN JULY AND SEPTEMBER, 1950. (Percentages on a dry-weight basis.) Mixture Com- ponent Frequency of cutting in weeks mixture Two Three Four Five Two Three Four Five per cent per cent July 1950 September, 1950 Broadleaf trefoil with grass Trefoil 77.0 87.8 91.5 91.2 46.8 58.1 75.1 81.0 Grass 22.7 10.5 7.7 8.8 50.0 38.6 23.5 19.0 Misc. 0.3 1.7 0.8 0.0 3.2 3.3 1.4 0.0 Ladino clover with grass Ladino 79.9 84.7 87.8 90.0 56.5 69.6 77.6 79.1 Grass 20.1 15.3 11.4 10.0 43.5 29.8 22.0 20.5 Misc. 0.0 0.0 0.8 0.0 0.0 0.6 0.4 0.4 Alfalfa 71.7 88.2 93 7 96 5 44 1 65 6 87 7 95 8 Grass 27.9 11.8 6.3 3.5 52.4 34.2 12.2 4.3 Misc. 0.4 0.0 0.0 0.0 3.5 0.2 0.1 0.0 Alfalfa, ladino, and trefoil with grass Alfalfa 6.1 15.9 67.0 94.2 1.1 8.3 70.5 87.4 Ladino 72.8 66.7 23.7 1.8 58.1 57.4 14.4 4.0 Trefoil 1.3 1.0 0.1 0.0 0.8 0.7 0.2 0.5 Grass 19.8 16.4 9.2 4.0 40.0 33.6 14.9 8.1 Source: Peterson and Hagan, 1953. 7] age, however, is generally most abundant in late spring and early summer, when yields gradually decrease until the low level in winter. The effect of cutting frequency upon botanical composition has been shown by Peterson and Hagan (1953). Table 1 shows that the percentage of grass present in Sep- tember was approximately double the amount present in July. This is not surpris- ing in view of the cool-season growth char- acteristics of tall fescue, orchardgrass and ryegrass. When alfalfa was the legume pres- ent in the mixture, it made a rapid recov- ery and more erect growth than ladino clover or trefoil. Trefoil in general is a poor competitor, especially in relation to other fast growing grasses or legumes. REASONS FOR GRAZING MIXTURES Even though a pasture mixture under opti- mal conditions yields only 80 per cent of that of alfalfa (figure 2), it is grazed much more frequently than alfalfa because bloat is a hazard for animals grazing immature alfalfa or a pasture containing a high per- centage of legumes. Several methods of prevention or control of bloat are presented in the review by Cole and Boda (1960): (1) Feed 3-5 pounds per head daily of dry roughage such as Sudan or oat hay to the grazing animal. (2) Mow strips and allow to wilt in the al- falfa field before turning the animals in to graze. (3) Let the alfalfa reach the full bloom stage before pasturing. (4) Cut al- falfa for soilage and let it wilt before feed- ing. (5) Keep at least 50 per cent of the grazed mixture grass or legumes that do not produce bloat, such as birdsfoot tre- foil. (6) Spray the field to be grazed with mineral oil. These are not all of the ways of preventing bloat nor are they 100 per cent effective for grazing animals but they will aid in cutting down the incidence of bloat. Another reason for grazing a mix- ture is to take advantage of the seasonal growth characteristics of both grasses or legumes; as previously mentioned, some will grow better under long hot days and some under the cooler shorter days. Alfalfa is also unsuitable on shallow and marginal land. We therefore recommend that mix- tures of grasses and legumes be grazed and alfalfa be grazed only during its semi- dormant period (late October to mid- February). Table 2 ALFALFA VS. PASTURE MIXTURE STEERS VS. LAMBS Item Beef Steers Average daily gain, pounds TDN content of forage dry matter consumed Feed per pound gain, pounds Average terminal carcass grade Beef produced per acre, pounds Beef produced as per cent of alfalfa Feeder Lambs Average daily gain, pounds TDN content of forage dry matter consumed Feed per pound gain, pounds Average terminal USD A carcass grade Lamb produced per acre, pounds Lamb produced as per cent of alfalfa Forage Yield per acre, dry matter, pounds Per cent yield of alfalfa Per cent dry matter consumed by cattle Alfalfa pasture Trefoil- orchardgrass pasture 1.66 1.75 60.7 66.4 11.8 12.9 standard high standard 447 359 100 80 0.34 0.31 66.1 67.4 7.9 9.1 choice choice 440 388 100 88 8,300 5,100 100 62 59 82 TYPE OF ANIMAL Grazing cattle and sheep respond differ- ently, as illustrated in table 2, showing carcass grade and animal response. The re- sponse also differs, depending upon the type of forage grazed. The TDN content of the trefoil-orchard- grass pasture consumed by sheep and cattle was about the same (table 2). However, from- the alfalfa pasture, the sheep selected a diet with a higher TDN content than the steers. The interaction of animal species and method of feeding was statistically sig- nificant. An important degree of selection was exhibited, however, by the steers on alfalfa pasture. The TDN content of for- age consumed by cattle illustrates selective grazing on alfalfa, but with lower-growing, dense forage, selective grazing is not mani- fested or, at least, TDN does not measure differences. The type of forage to be util- ized should therefore determine the type of animal to graze. Selective grazing, resulting in refusal to eat coarse alfalfa stems, together with the higher TDN of the trefoil-orchardgrass, tended to narrow the importance of differ- ences in yield between alfalfa and trefoil- orchardgrass. Table 2 also shows that tre- foil-orchardgrass produced 62 per cent of the dry matter produced by alfalfa. The steers, however, produced 80 per cent as much meat from an acre of trefoil-orchard- grass as they did from alfalfa even though alfalfa produced a greater yield of dry mat- ter. An even greater utilization (88 per- cent) was made by sheep. Yield of forage dry matter, therefore, does not correctly appraise its value for animals. The final analysis will always have to be with animals as the measuring unit. Utilization of the grazed forage by sheep or cattle occurred to a different degree as shown by slaughter grades (figure 3). The number of steers given trefoil-orchardgrass which graded in the "good" slaughter grade was greater than the number grazing alfalfa. The lambs, however, reached a "choice" slaughter grade when allowed to graze. It was also found that the lambs consuming trefoil-orchardgrass attained a "choice" slaughter grade in fewer days than the lambs grazing alfalfa. In general, it appears that sheep are su- perior to steers in their ability to utilize pasture. This was borne out by daily gains, feed consumption, efficiency of feed utiliza- tion and type of gain on pasture. DAILY RATION VS. WEEKLY ROTATION The method where animals receive their forage in a long narrow strip, as if it were offered to them in a long manger or feed bunk, is called daily-ration or strip grazing. This method reduces trampling losses to a minimum, and feces and most of the urine falls on an area which has already been grazed. This type of grazing was compared to rotational grazing where animals grazed a field from six to ten days. Tables 3 and 4 give the comparisons. Decreasing the grazing interval increased production per acre. However, it did not appear practical to reduce the grazing interval to less than six days. Even the intensive strip grazing method where fresh forage was given daily was little better than a six-day rotational grazing interval. It was concluded that, de- pending upon feed supply and the neces- sary irrigation cycle, rotating the cattle every five to seven days to a new field would give near optimum beef per acre from grazing. RECOVERY INTERVAL Studies were conducted during two pasture seasons on the effect of forage recovery in- tervals of 24, 30 and 36 days. The stocking rate was held approximately equal in all treatments to obtain the same degree of grazing intensity. Both animal response, forage yield, and botanical composition data were obtained. The data indicated that the forage was grazed when in a vegetative stage (figure 4). No large differences were noted in TDN, crude protein, and lignin content of the grazed forage. Recovery interval of the forage did not influence steer response as measured by daily gain, feed consumption, efficiency of feed utilization, liveweight, dressed weight or energy gain per acre (table 5). Even though there appears to be a tendency for lowered production on the 36-day interval, these differences are not statistically significant. It may be, there- fore, that with the type of pasture studied in these trials, a 36-day recovery period is 9] STEERS ALFALFA LOTS 10 co 5 61 90-| ZO -so 40- 30- Z0- /o- 10- 30- zo /o- - S//S - 3/3Q ss S4 jr/// - s//+ S/X6 - 6/6 f.4 3.6 */U- 6V3 '/' - 4*' S3 3//S- 7/zS 3* t/r-r/y 6/6 - r/'T /.3S 3S SJ AS 36 s+ 7/Z7 -3/3A AS 3f 3* 7//S-3/Z3 fS 36 3+ /.S3 3.S S.A 3/3/ - S/s/6ff AS 3.3 S+ 3/jjt - f/zo/tA // 3.6 3* 3/zs - */*S/Si /& 6**j/#4 Z** &CMM* 3** 6**z/a/6 Pxf4***/A/3 [12] 90 1st GRAZING 2nd GRAZING 3rd GRAZING 1st CUTTING 80 5/19-6/30, 1959 7/1 -8/11, 1959 8/12-9/15, 1959 3-31-5/5, I960 - 70 - - 60 >■> -o 0) °-5.0 ~ -Q 3 40 - a> — >- a> O. in F O e o E — E 20 O CO o CO c = = = = o CO cz o CO to in CO ro QO lO LO CO ro lo ir> CD ro CD IT) ir> CD ro CD ro CO o o> CD ro CO O co ro CO O CD CD rO CO O ' \ / ^y/^ ''' ;S /j/s"~"~ V \ ' Ss' '/^ X Digestible energy consumed — Live weight gain _ Corrected carcass gain 1 ' 1 8000 - 4000 cc 2000 3.0 4.0 ANIMALS GRAZED PER ACRE [14 the season, as related to forage growth, would give maximum production of beef from the irrigated pasture throughout the season. The reason for this is that cattle at the lighter stocking rates in relation to for- age growth would contain more fat in their weight gain whereas at the heavy stocking rates more animals are carried per acre, again in relation to forage growth, but their weight gain contains less fat. Thus weight gain per head and gain per acre would be equal for their respective parts of the grazing season. CONTINUOUS VS. ROTATIONAL GRAZING SYSTEM The controversy regarding continuous or rotational systems of grazing management appears to be far from settled. The species of plant used and the type of animal grazed may be as important as the type of grazing management practiced. There is evidence that rotational grazing may be advantageous over continuous grazing at high stocking rates. Because of the interaction between method of grazing and stocking pressure, an experiment was designed to compare rotation and continuous grazing with beef steers where (1) stocking rate was not lim- iting and (2) where higher than optimal grazing pressure was achieved by (a) a higher than normal stocking rate well within the season of adequate forage pro- duction, and (b) an optimal stocking rate with the grazing season extended beyond the period of adequate forage production. This experiment was conducted for each of three years. Plant cover and botanical composition were determined during the final year of the experiment. The treatments were: (1) six-field rotational grazing, (2) two-field continuous grazing. Both management systems were studied at: (a) medium stock- ing rate and grazing pressure over the sea- son of rapid forage growth, (b) heavy stock- ing over the season of rapid forage growth, (c) medium stocking over the season of rapid forage growth and adjusted so the forage would not be limiting when the Table 8 STEER RESPONSE TO GRAZING SYSTEM AND PRESSURE (Average for three years) Rotational grazing || Continuous grazing|| Item Grazing pressure Grazing pressure Medium Heavy Extended Medium Heavy Extended Animals carried per acre*|. Animal days grazing Average daily gain, pounds. Initial weight, pounds Final weight, pounds Carcass data: Final weight, pounds Dressing percentage 2.9 918 1.14=d 561» 728 = 387 = 53. 2d 11.7=d 19.1 b = 302 =d 3.4d 2.7 = 0.24 8.8 194cd 4.4 1,356 1.02b 571* 709 = 373 = 52. 5 d 10.0 de 19.4*b 268 d 2.6* 2.3 d 0.24 8.5 128d 2.9 1,121 1.16=d 568 » 779b 424 f 54.9 = 12.6 b = 18.0=d 332b = 3.8 = 3.2b 0.22 9.1 253b c 2.9 820 1.52»b 579 » 798»b 446b 55.9b 13.7*b 18.78= d 367b 4.4b 3.4b 0.33 9.2 308*b 4.4 1,113 1.28b 548 » 708 = 385 = 54.9 = 9.5 = 19. 6» 272d 3.3« 2.5=d 0.21 8.8 154 d 2.9 1,023 1.63* 558» 839* 488* 58. 0» 15. a 18.3 d Fat corrected carcass, 422 » Final carcass grade X 4.8" 3.8» Backfat thickness, inches. Ribeye area, square inches Energy gain, megcals 0.37 9.9 399" * Initial stocking rates only. t 2.16 acres per treatment. t 3 = standard, 6 = good, USDA grades. § 2 = practically devoid, 3 = traces, 4 = slight, USDA scores. || a, b, c, d, e, f. Means on the same line having the same superscript do not differ significantly P < .05. [15] grazing was extended into the season of slow forage growth. When grazing systems are compared, large differences are apparent in animal days grazing (table 8). These differences have special significance as the steers on the continuously grazed treatments occa- sionally had less feed available than was necessary for maintenance. These lots therefore were supplemented with alfalfa hay. Gains due to alfalfa hay were not credited to the trial. As the stocking rate increased 32 percent from the medium to the heavy, the continuously grazed treat- ments were supplemented 98 and 243 days respectively, depending upon stocking rate. The rotationally grazed animals also had less than maintenance amounts of feed available at various times during the graz- ing season but this lack of forage occurred only when one or two days remained be- fore they were to be moved to another field with adequate forage available. They therefore were not supplemented. This factor of supplementation, as reflected in animal days grazing, would be quite im- portant when determining what type of grazing system a pasture operator should use. Significant differences were found in the average daily gain (table 8). These differ- ences depended upon grazing pressure and were in favor of the continuously grazed steers. This increase in daily gain, as re- flected by final weight, may or may not be of advantage depending upon the size of the animal desired at the end of the graz- ing season. Under either system of grazing management the steers were of feeder grade with undesirable finish for slaughter grade, as shown by carcass data. Extending the grazing season, especially under continuous grazing, markedly in- creased energy gain and liveweight gain per unit area (table 9). It should be noted that liveweight gain per acre does not give the magnitude of difference that energy gain per acre demonstrates. An interaction between beef production, stocking rate, and grazing system was ob- served. Medium grazing pressure was better than heavy grazing pressure for both systems but not as good as extended graz- ing for the continuous system. When grazing systems are compared on an energy basis, extended grazing definitely was greatest for continuous grazing and under this system heavy stocking pressure defi- nitely was not favorable. It appears that rotational grazing would yield the most per-unit area when stocked heavier than that which would give opti- mum animal daily gains, and that, to ob- tain maximum production per unit area under continuous grazing, it should be stocked for optimum daily gain per indi- vidual. Final livewight gain would also be a criterion in determining the grazing sys- tem to practice. An additional aspect of these trials was the influence of grazing management sys- tem upon plant species (table 10). The grazing management systems allowed a Table 9 RELATIVE COMPARISONS OF GRAZING SYSTEMS AS DETERMINED BY GRAZING STEERS (Highest treatment set at 100 per cent) Rotation grazing Continous grazing Item Grazing pressure Grazing pressure Medium Heavy Extended Medium Heavy Extended per cent (Highest treatment set at 100 per cent) 68 65 65 48 100 79 54 46 S3 79 65 61 60 76 86 71 82 70 57 48 68 100 Liveweight gain per acre per animal day 100 100 [16] Tableau PER CENT OCCURRENCE OF PLANT SPECIES DURING THIRD YEAR OF GRAZING Plant species Rotation grazing Grazing pressure Continuous grazing Grazing pressure Medium Heavy Extended Medium Heavy Extended per cent Orchardgrass Rye grass Fescue Total Legumes Ladino clover Strawberry clover Total Weeds, etc 52.4 10.1 27.5 3.7 2.8 6.5 3.5 47.6 47.7 43.7 44.2 9.7 8.6 20.1 21.2 16.1 25.0 5.6 4.8 73.4 81.3 69.4 70.2 13.9 10.2 10.8 6.9 4.3 4.5 14.3 15.9 18.2 14.7 25.1 22.8 8.4 4.0 5.5 1.0 27.3 25.5 1.7 54.5 13.3 27.0 40.3 5.2 marked shift in botanical composition to occur. In general, a higher proportion of legumes was maintained in the heavily grazing treatments. The continuous treat- ments also seemed more desirable as far as the height of the sward was concerned, re- sulting in the sward being maintained in a more vegetative condition, therefore in a more productive state. In addition, the rotationally grazed pastures were more sus- ceptible to invasion by tall fescue which was not utilized as well as the other grasses. There seemed to be a need for more frequent irrigations for the continu- ous grazed areas. The heavy grazing pres- sure under rotation grazing did not seem to hurt the sward but this may have been because of the 35-day enforced recovery period which allowed the plants to recover from an oppressive stocking rate. In general, when choosing a grazing management system, several criteria should be taken into consideration, such as graz- ing season, type of forage, type of animal, stocking rate, recovery interval desired, and whether to use continuous or rota- tional grazing. Different methods of utili- zation and management must result in a compromise between plant and animal relationships. GRAZING BEHAVIOR DAY IN THE FIELD A knowledge of the behavior of grazing animals is important to a complete under- standing of productive performance. Cor- relation of these behavior patterns to their productive performance on various types of forages is also important. A series of 24-hour observations were made on both sheep and cattle grazing alfalfa or trefoil-orchardgrass pastures. These observations were made starting at noon on the second day in a new field and terminating at noon of the third day. A second 24-hour observation was started at noon of the fifth day in the field and terminated at noon on the sixth. For con- venience, these two observations are re- ferred to as the second and fifth day. Their purpose was to determine possible changes in behavior when animals are grazing abundant, compared to scant, forage. The [17] Table 11 BEHAVIOR PATTERNS OF STEERS AND LAMBS EATING ALFALFA AND TREFOIL ORCHARDGRASS FORAGE Pasture Eating green forage Eating hay- Ruminating Steers Sheep Steers Sheep Steers Sheep hours Alfalfa: 6.1 7.9 6.7 6.4 6.9 10.1 8.6 9.0 1.5 1.0 0.7 0.8 0.2 0.2 0.2 0.5 4.4 7.7 5.9 7.7 3.1 3.4 Trefoil-orchardgrass : 4.5 Fifth day in field 4.4 size of the fields were adjusted so that forage would be well utilized at the end of six days. The average amount of time spent eat- ing green forage, eating hay, and rumi- nating in a 24-hour day is shown in table 11. Changes in the time spent grazing and that spent ruminating are shown by hourly intervals in figure 8. Ruminating time in- cludes both standing and lying. There are a number of interesting ef- fects noticeable from these data. Both steers and sheep spent more time grazing on alfalfa pasture the fifth day in the field than they did on the second day. This is shown in figure 8 by the increase in the amount of time spent grazing per hour during grazing, and also in the case of the steers, by the increase in the number of hours during which some animals were grazing. On trefoil-orchardgrass pasture, however, there was no difference in graz- ing time between the second and fifth days. The difference in the grazing pattern of steers and sheep on alfalfa pasture is interesting. The periods of grazing were more definite with steers than with sheep. This is particularly noticeable on the second day where some sheep were grazing well into the night while steers grazed only during one hour after dark. The difference between steers and sheep in the time spent ruminating is important. On both alfalfa and trefoil-orchardgrass the steers spent more time ruminating the fifth day than on the second. The reason for this is the increased time spent per hour — the time of day during which ruminating occurred did not change (figure 8). The sheep, however, ruminated the same length of time each of the two days, and the pattern of time spent ruminating the two days was similar. Steers spent more time ruminating on both days than did the sheep. The TDN content of the forages as de- termined is a measure of the average digestibility of the forage over a given six- day period (table 12). Because of the close relationship, however, of the ruminating time (RT) to eating time (ET) ratio to TDN of alfalfa forage, an opportunity is provided to estimate the changes in TDN of alfalfa forage selected on the second and fifth days on a pasture (table 13). By use of the regression equation. Y = 8.3-0. 12X (r = -0.89, S Y . X = 0.14) and the ratios of 0.72 and 0.97 for steers on alfalfa pasture it is estimated that they con- sumed a forage containing 63.3 and 60.8 per cent TDN on the second and fifth days, respectively. The sheep, on the other hand, showed little difference in the RT/ET ratio between the second and fifth days on either alfalfa or trefoil-orchard- grass pasture table 14). It can be con- cluded therefore, that the sheep, but not the steers, even on the fifth day in the field were able to select forage of high digestibility. The differences in behavior pattern on the two types of forage seems to be related to the ability of the animals to graze selectively. SELECTIVE GRAZING As mentioned, the variations between sheep and cattle in utilization of forage [18] Table 12 RELATIONSHIP OF DRY MATTER AND TDN CONSUMPTION TO TIME SPENT EATING FOR STEERS AND LAMBS Alfalfa Trefoil-orchardgrass Animal Dry matter consumed TDN consumed Eating time Dry matter consumed TDN consumed Eating time pounds 14.6 2.36 pounds 8.9 1.56 hours 7.0 8.5 pounds 19.0 2.70 pounds 12.6 1.82 hours 6.6 8.8 Table 13 RATIO OF RUMINATING TIME (RT) TO EATING TIME (ET) THE SECOND AND FIFTH DAYS IN A FIELD FOR STEERS AND LAMBS Pasture RT/ET Steers Sheep Alfalfa: 0.72 0.97 0.88 1.20 0.45 Fifth day 0.34 Trefoil-orchardgrass : 0.52 Fifth day 0.49 Table 14 RELATIONSHIP OF DIGESTIBILITY TO THE RATIO OF RUMINATING TIME (RT) TO EATING TIME (ET) FOR STEERS AND LAMBS Animal Alfalfa Trefoil- orchardgrass TDN RT/ET TDN RT/ET Steers Sheep per cent 60.7 66.1 0.85 0.40 per cent 66.4 67.4 1.04 0.51 Fig. 8. Grazing behavior of steers and sheep as influenced by type of pasture and day in the field. [19] !%l \? S M e^!f»1 r .* ' '*?&, Fig. 9. Above: The refused al- falfa left after six days grazing by steers. Fig. 10. Left: The refused al- falfa left after six days grazing by sheep. J&I are based on differences in abilities to select forage. The TDN content of the trefoil-orchard- grass pasture consumed by sheep and cat- tle was the same. However, in the alfalfa pasture the sheep selected a diet which had a higher TDN content than that selected by steers. The interaction of animal species and method of feeding was statistically sig- nificant. An important degree of selecttion was exhibited, however, by the steers on alfalfa pasture as evidenced by the 60.7 per cent TDN compared to 66.4 per cent TDN in trefoil-orchardgrass pasture (table 14). Superior selective grazing ability of the sheep compared to the steers is also demonstrated in comparing figures 9 and 10. The remaining forage from the steer alfalfa pasture exhibits more leaves un- consumed than those left by sheep. It was very apparent throughout the trial that very few leaves were missed during grazing by the sheep whereas the steers did not seem to attempt or were unable to select as many leaves. Another indication that sheep did more selecting than cattle is contained in the fact that sheep consumed much less dry matter from one acre in all treatments than steers (table 15). This was particularly true for the sheep grazing the alfalfa pas- ture. The increased TDN content of the alfalfa forage selected by the sheep was not enough, however, to compensate com- pletely for the lowered dry matter intake. The sheep, therefore, consumed less TDN than the steers from alfalfa pasture. How- ever, they produced as much meat per acre as did the steers. The data also show that the sheep made a fattening gain while the steers did not. Even though the gain of the sheep probably contained more energy be- cause of their finished condition, more meat was produced per 100 pounds of TDN consumed by sheep on alfalfa pas- ture than steers on the same treatment (table 15). In other words, the TDN selected by the sheep contained more net energy than the TDN selected by the steers. In general the trefoil-orchardgrass for- age consumed contained more TDN than the alfalfa forage (table 15). There was one exception. The sheep on alfalfa pas- ture did a superior job of selection and actually consumed an alfalfa forage with as high a TDN as that consumed from the trefoil-orchardgrass pasture. The interac- tion of method of feeding and plant species was statistically highly significant which gives weight to this evidence. Table 15 also shows that the gain for the sheep per 100 pounds of TDN consumed from alfalfa pasture was larger than the gain by the sheep on trefoil-orchardgrass pasture. Selective grazing which resulted in re- fusals to eat coarse alfalfa stems together with the higher TDN of the trefoil- orchardgrass tended to narrow the im- portance of differences in yield between alfalfa and trefoil-orchardgrass. Table 15 shows that trefoil-orchardgrass produced 58 to 63 per cent of the dry matter pro- duced by alfalfa. The steers, however, produced 80 per cent as much meat from Table 15 COMPOSITION OF FORAGE DRY MATTER AND TOTAL DIGESTIBLE NUTRIENTS* Steers Sheep Pasture Dry matter available Dry matter consumed TDN consumed Gain/100 pounds TDN consumed Dry matter available Dry matter consumed TDN consumed Gain/100 pounds TDN consumed pounds per acre pounds per acre Alfalfa Trefoil- orchardgrass... 2,711 1,567 1,612 1,389 978 921 14.3 11.9 2,691 1,437 1,252 1,345 832 906 19.3 16.4 Average consumption during three collection periods. [21] LOT NUMBER Fig. 11. Behavior of steers grazing irrigated pasture at vari- ous stocking rates (1.35, 2.25, 3.06, 3.93, 4.68 steers per acre) for lots 1 through 5, respectively, and time spent eating soilage for lot 6. Values with different super- script letters are significantly dif- ferent. 40 S 20 CO 10 40 en | 30 ^20 10 50 40 ~30 _i 20 10 i 2 ; s <■ \ f ) 6 — I— ~ ] — Tl pfl 32. b 34. 9 C 38 6 d 37. 5 e 40 .i e 22.4° III _L 1 III III 1 1 III i-n-n 2l.5 b III 2l.5 b III rTL I9.0 b 1 ml I7.8 b ~~] Mil rfL r 21. 3 b III 27. 1° - III 46.5° LL 43.7 bc Hi 42.4 C ILL 38. 6 d ILL 357 1357 1357 1357 DAY IN FIELD 13 5 7 50.5° 11 13 57 one acre of trefoil-orchardgrass as they did from alfalfa even though alfalfa produced a greater yield of dry matter. An even greater utilization was made by the sheep. The sheep produced 89 per cent as much meat per acre from the trefoil-orchardgrass as from the alfalfa. Yield of forage dry matter, therefore, will not correctly appraise its value for ani- mals. The final analysis will always have to be with the animal as the measuring unit. Even here a great deal of caution needs to be exercised because of differ- ences in the composition of weight gains and possible influence of improper weigh- ing conditions if the animals are not shrunk before weighing. It is concluded, therefore, that selective grazing is more apparent and to a higher degree on a tall, sparse-growing plant than on a low, dense forage plant. Sheep are also more selective than cattle. STOCKING RATE Grazing intensity or stocking rate has an influence on animal performance as pre- viously stated. The stocking rate can also have an influence on grazing behavior. Fig- ure 1 1 shows that as stocking rate increases grazing time increases but only up to a point. As the stocking rate was progres- sively increased from 1.35 to 3.06 head per acre, significantly more time was spent grazing and less time standing or lying be- cause, no doubt, competition for forage became greater as grazing intensity in- creased. As the stocking rate increased from 3.06 to 4.68 head per acre, the time spent graz- ing did not increase significantly, but the time spent lying did. It therefore appears that an animal will only spend so much time grazing (approximately 10 hours per day) even if forage available is below its needs. SOILAGE Soiling (green chopping) the cutting and hauling of green forage to livestock has been practiced for many years. Its main use, however, has been to supplement pas- ture during periods of limited feed produc- tion. At such times some high-yielding crop has been grown specifically for soiling pur- poses. Depending upon the type of pasture [22 Table 16 DAILY GAINS AND FEED UTILIZATION FOR STEERS USING DIFFERENT HARVESTING METHODS Item Six day rotational Strip grazing Soiling Haying Daily gains, pounds Feed 'consumption, pounds Gain per 100 pounds of feed Beef production per acre, pounds. Daily gains, pounds Feed consumption, pounds Gain per 100 pounds of feed, pounds. Beef production per acre, pounds — 1954 (132 day?) 1.62 13.9 11.7 1.65 19.2 1.42 12.8 10.0 739 1.40 15.0 9.3 1956 (108 days) 447 1.34 23.0 5.8 563 1.13 19.0 5.9 856 and the crop available for soiling, the econ- omy of such a program varies considerably. It has usually been true that the cost of soiling has limited the practice. Recently, however, interest has been revived, particu- larly in the alfalfa-growing regions of the West, where soiling has been used to re- place, rather than supplement pasturing. The use of modern labor-saving forage har- vesting and self-unloading wagons may make soiling an economical replacement for pasturing. SOILAGE VS. HAYING OR PASTURING Since alfalfa is California's most important and highest yielding irrigated forage crop, this forage was considered for use as soil- age. The alfalfa was fed as hay, pasture or soilage. Of the various methods studied, soilage produced the greatest beef produc- tion per acre from alfalfa followed by hay- ing and pasturing in that order (table 16). SOILAGE FOR SHEEP As noted, sheep will reach an acceptable slaughter grade on pasture earlier than cattle. This is attributed to the selective grazing ability of the sheep resulting in a very nutritious forage consumed. This is no longer apparent to such a degree when soilage is fed. For lamb feeding, green chop alone cannot be expected to replace a hay and grain mixture because of lack of ade- quate feed consumption and/or selection by the animals. It would also be advisable to feed grain in with the soilage unless the forage is fed several times a day. The dry matter of the soilage is extremely variable, usually about 8 to 25 per cent, depending on the stage of maturity and weather con- ditions when the forage is harvested; also forage species composition will have an effect. Crude protein is usually above 15 per cent unless the forage is quite mature. The TDN is commonly 65 to 70 per cent on a dry basis or about halfway between that of a good hay and grain. This is higher than it would be from hay made from the same pasture, partly because hay is often cut at a later stage and partly be- cause nutrients are lost during the curing process, particularly under most haying conditions. The high moisture will heat the soilage in the feed bunks; thus, for sheep fresh soilage should be furnished at least two times per day. If soilage is fed to sheep, it should be used for feeding groups of ewes or other sheep not on a fattening diet. When either alfalfa or trefoil-or- chardgrass forage was fed as soilage, there was no difference in the TDN content of the forage consumed by either sheep or cattle (table 18). Apparently neither species was able to select out a highly nutritious diet but consumed all of the harvested plant. In the case of sheep, their nutrient intake was not great enough to produce a fattening gain. [23] Table 17 EFFECT OF FORAGE TYPE ON STEER UTILIZATION FROM ONE ACRE OF FEED Forage type Dry matter available Dry matter consumed Amount consumed Gain per 100 pounds of forage 1954: Alfalfa soilage Alfalfa pasture 1956: Alfalfa soilage Alfalfa pasture 1956: Trefoil-orchardgrass soilage. Trefoil-orchardgrass pasture pounds 7,659 7,198 2,688 2,711 1,562 1,567 pounds 3,743 2,460 1,612 1,517 1,389 per cent 52 pounds 9.3 11.9 5.8 8.6 8.4 7.7 Table 18 ALFALFA VS. PASTURE MIX- STEERS VS. LAMBS* Item Alfalfa Soilage Trefoil- orchard- grass Soilage Beef steers Average daily gain, pounds. 1.50 1.76 Feed per pound gain, pounds 17.1 12.1 TDN content of forage DM consumed 56.5 66.0 High- Average terminal grade Standard standard Beef produced per acre, 563 444 Feeder Lambs Average daily gain, pounds. 0.21 0.24 Feed per pound gain, pounds 15.0 10.6 TDN content of forage 58.0 High-good 64.5 Average terminal grade High-good Lamb produced per acre, 463 417 SOILAGE FOR CATTLE Even if cattle select a more highly nutri- tious forage from pasture, soilage results in greater production because more of the available dry matter is consumed (table 17). Only 52 to 59 per cent of the available forage on alfalfa pasture was consumed compared to 90 to 92 per cent from soilage. Trefoil-orchardgrass was a more nutritious forage (table 17), and a greater proportion (82 per cent) was consumed by pasturing. Haying, although producing more beef than pasturing, produced only 79 to 85 per cent as much as soiling (table 19). Hay- ing and soiling produced lower gains than grazing, even though the steers consumed more feed. Efficiency of forage utilization was also lowest for steers fed alfalfa as hay. It must be kept in mind, however, that greater quantities of beef were produced from soiling followed by haying. Length of trial - 108 days. Table 19 BEEF PRODUCTION PER ACRE FROM DIFFERENT METHODS OF UTILIZATION Rotation grazing Soilage Year 10 day 6 day 1 day Strip Fresh WUted Haying per cent of production from soilage 1952 59 77 64 80 82 79 68 100 100 100 100 81 1953 85 1954 79 1956 [24] Even wilting the alfalfa to 40 per cent moisture before feeding produced less beef than soiling (table 19). Grazing and soiling produced comparable gains but the ani- mals fed soilage consumed more feed and produced less gain per unit of feed (table 17). The higher feeding value of soilage compared to hay is further illustrated by the greater quantities of concentrates needed to fatten steers when hay was fed (table 20). In this trial lower gains resulted from hay feeding than from soilage feed- ing, but when soilage and hay were sup- plemented with concentrates gains were Table 20 STEER RESPONSE TO CONCEN- TRATE SUPPLEMENTATION (1957) Daily gain Feed intake Feed Roughage Concen- trate pounds 1.96 1.60 2.21 2.16 pounds pounds Unsupplemented 17 7 Hay 18 2 Supplemented 21.5 5 5 Hay 11.5 7 7 Table 21 BEEF PRODUCTION PER ACRE FROM ALFALFA Year Days Soiling 1 Fresh Wilted Haying 168 155 132 108 pounds beef per acre 1952 704 678 1,080 563 568 1953 576 1954 856 1956 almost equal because greater concentrate consumption resulted thus overcoming the lower quality of the alfalfa hay. It appears that pasturing allows steers to consume a higher-quality forage. Soilage has a lower quality than pasture because animals are forced to consume more of the coarser parts of the plant. Hay, however, is still of lower quality than soilage because leaf and fine stem losses occurred in hay making. Soilage prevented not only the animal-induced forage loss in pasturing but also the machine-induced forage loss because it is a drier product to handle. In general, the average increase found from soilage in California trials has been about 30 per cent. It was concluded that soilage will give the greatest production per acre from the same forage. This, however, doesn't mean that it is always the most economical method for forage utilization. Unless there are other considerations, soiling is the most productive method of processing forage for greatest beef produc- tion per acre. Even though TDN, for the most part, will measure differences in forage quality, it is not the ultimate in the measurement. This is noted when gain produced per 100 pounds of TDN is computed. The TDN consumed by the steers on pasture was util- ized more efficiently than that consumed from soilage or hay. Soilage exceeded hay. The TDN of the pasture, therefore, has a higher net energy than the TDN of soilage or hay. This conclusion emphasizes the need for the measurement of forage value to be on some basis which involves the net- energy principle. Table 21 gives some beef production fig- ures for soilage. Note that more than 1,000 pounds of beef per acre can be obtained from this method of forage utilization. SUPPLEMENTATION Supplementation of grazing cattle has been practiced for many years. Although rela- tively good gains can be achieved when the sole source of feed is high-quality pasture forage, it is well recognized that an addi- tional source of energy is needed to pro- duce a finished animal with a high dressing percentage and a high grading carcass in a reasonable feeding period. [25] Table 22 SLAUGHTERING DATA OF STEERS SUPPLEMENTED FOR VARYING PORTIONS OF THE TOTAL FEEDING PERIOD Supplemental treatment Dressing percentage Carcass grades Choice Good Standard or commercial per cent None Supplemented 2nd 84 days Supplemented for 168 days 56. 7* 58.9* 75 All statistically significantly different (P = . 05) . SUPPLEMENTATION OF ALFALFA Although relatively high gains can be achieved when high-quality alfalfa in the form of soilage or hay is the sole source of feed, an additional source of energy is needed to produce an acceptable slaughter animal (table 22). It was shown in an earlier study (Meyer et al., 1953) that bar- ley, fed at the rate of 1 pound per 100 pounds of body weight to steers receiving pasture, brought about an increased daily gain of approximately 0.5 pound. Table 23 gives similar results for steers grazing trefoil-orchardgrass pasture. Molasses alone was shown to be unsatisfactory as a supplement to alfalfa soilage. Other ob- servations have revealed that a mixture of Table 23 EFFECTS OF LIMITED SUPPLEMEN- TATION FOR STEERS GRAZING TREFOIL-ORCHARDGRASS PASTURE Amount of supplement fed Item 5 pounds per head per day 142 21 634 1.50 57.9 5 86 9 142 21 Initial weight, pounds Average daily gain, pounds. . . . 631 1.75 60.8 Carcass grade: per cent of animals in grade Good 67 33 Utility barley and molasses-dried beet pulp (here- after referred to merely as beet pulp) is a satisfactory supplement to both alfalfa soil- age and hay. Steers fed alfalfa alone have consistently made good body weight gains, especially during the first half of a 130- to 179-day feeding period, in contrast to steers receiv- ing supplements continuously for the en- tire period. It seemed important to deter- mine whether a concentrate supplement fed only during the last half of the feeding period produced gains comparable to those produced by supplementing continuously for the entire period. It also seemed im- portant to determine at what level the sup- plement should be fed. SUPPLEMENTATION OF ALFALFA SOILAGE AND HAY Yearling Hereford steers weighing approx- imately 665 pounds were randomly as- signed to six groups for an experiment. The hay fed had been harvested at approx- imately 10 per cent bloom at the Imperial Valley Field Station the summer preceding the study; soilage had also been harvested at 10 per cent bloom. Hay or soilage was allowed ad libitum. Barley and beet pulp were fed in a ratio of 3:1, and supple- mented lots were allowed all the supple- ment they would eat twice daily. All lots were allowed a small amount of oat hay (approximately 1.8 pound daily) to assist in preventing bloat. Statistical analysis revealed no signifi- cant difference in response to the supple- ments between the animals fed soilage and those fed hay. The daily gains and the [26 roughage consumption of hay or soilage were not significantly different. The sup- plemented steers on hay, however, con- sumed an average of 2.2 pounds per head per day more concentrate than those on soilage. Since the gains were not different, the hay, therefore, was of lower nutritive value than soilage. Because the response to supplement is similar, the data from the lots fed hay have been combined with those from the lots fed soilage and are pre- sented in table 24. Concentrate supplementation during the second half of the feeding period re- sulted in a highly significant increase in daily TDN consumption of 3.2 pounds per day, although there was a significant drop in roughage consumption. The daily gain in the same period was increased by 0.72 pound. Daily gain of the unsupple- mented lot dropped 0.22 pound during the second half of the feeding period. How- ever, providing 7.6 pounds of concentrate daily prevented this loss and increased the daily gain 0.37 pound above the gain of the first half. Supplementation throughout the 168-day period resulted in a further decrease in roughage consumption with only a slight increase in TDN intake. The daily gain was not increased over the group receiving supplement only during the last half of the period, although approxi- mately 75 per cent more supplement was used over the 168 days. It appears from these data that supple- mentation throughout the feeding period is wasteful of concentrate, because the ex- tra supplement reduced roughage intake but did not increase weight gain. Inspec- tion of the slaughter data shows that those steers supplemented throughout the 168 days, although gaining no more, yielded a significantly higher percentage of dressed carcass and graded considerably higher (table 22). A higher energy ration, there- fore, may produce fatter carcasses without increasing the rate of gain. Further calculations estimate the daily energy gain of 2,644, 4,049 and 5,722 kilo- calories for the unsupplemented lots, for those supplemented the last 84 days, and for those continuously supplemented, re- spectively. The lot receiving continuous supplementation thus gained 40 per cent Table 24 RESPONSE OF STEERS SUPPLEMENTED FOR VARYING PORTIONS OF THE TOTAL FEEDING TIME Supplemental Steers Portion of feeding period Initial weight Daily gain Daily air-dry feed intake Daily TDN Roughage Concentrate intake Number days pounds None 12 1st 84 days 2nd 84 days 670 829 1.89 1.67 16.7 19.2 8.9 10.2 Entire period (average) 670 1.78 18.0 9.6 Supplemented 2nd 84 days 11 1st 84 days 2nd 84 days 666 836 2.02 2.39 16.2 14.1 7.6 8.6 13.4 Entire period (average) 670 2.21* 15.2* 3.8 11.0* Supplemented for 168 days 11 1st 84 days 2nd 84 days 660 870 2.50 1.86 12.2 11.8 5.7 7.5 10.9 12.1 Entire period (average) 660 2.18* 12.0* 6.6* 11.5* * Difference statistically highly significant, aa compared to the unsupplemented lot. [27] more energy than the lot supplemented only the last 84 days, although the gain in body weight was the same for the two lots. A consideration of all data prompts the conclusion that, in order to produce a high- grading and high-yielding carcass, continu- ous supplementation was more satisfactory than no supplementation or supplementa- tion only during the last half of the feed- ing period. AMOUNT OF SUPPLEMENT TO FEED WITH ALFALFA High-quality Hereford steers were ran- domly divided into six lots of eight head each. Five of the lots were allowed alfalfa soilage ad libitum with various levels of barley and beet pulp supplement. One lot received no supplement, while a second received all the supplement they would eat twice daily. The remaining three lots being fed soilage received the supplement at the rate of 25, 50, and 75 per cent of the amount consumed by the full-fed lot. The sixth lot was allowed alfalfa hay ad libitum plus the supplement full fed. The alfalfa soilage and hay were again harvested from the Imperial Valley Field Station at ap- proximately 10 per cent bloom. Feeding a supplement (table 25) above 3.5 pounds per head per day (50 per cent of full feed) to animals on alfalfa soilage produced no significant increase in weight gain. Increasing the supplement to 5.1 and 6.2 pounds per day (75 to 100 per cent of full feed) brought about an increased TDN consumption but no increased weight gain. It is again interesting to note that the steers full-fed supplement on al- falfa hay ate more concentrate than those full-fed supplement on alfalfa soilage. The difference in gain was not statistically sig- nificant. As in the case of the previous experi- ment, if only body weight gain and TDN consumption are considered, erroneous conclusions may be made. From these data alone it appears that there is no advantage to feeding more than 50 per cent of full feed or 3.5 pounds per head per day (ap- proximately 0.5 pound per 100 pounds body weight). Again, however, if yield and grade data are considered, the conclusion is altered. Although increasing the supple- ment above 3.5 pounds did not signifi- cantly stimulate daily gains, it brought about a significant increase in the dressing percentage and carcass grade (table 25). It was concluded that gains made by steers continuously supplemented with Table 25 RESPONSE OF STEERS TO SUPPLEMENTS FED AT DIFFERENT LEVELS WITH ALFALFA SOILAGE AND FULL FED WITH HAY Alfalfa soilage Alfalfa hay Measurements Supplement fed at following percentage of full feed Supplement full fed 25 50 75 100 Initial weight, pounds 541.0 2.01 18.3 0.0 545.0 2.17 17.1 1.8 543.0 2.28 14.6 3.5 542.0 2.34 14.0 5.1 543.0 2.35 12.5 6.2 539.0 2.53 Daily air-dry feed consumed, pounds 11.7 Concentrate 8.5 Total 18.3 10.1 58.5 7 1 18.9 10.7 57.7 8 18.1 10.7 58.3 1 7 19.1 11.6 59.7 4 4 18.7 11.6 59.8 3 5 20.2 TDN intake, pounds per day 12.7 60.4 Carcass grade, number in grade 4 Good 4 Standard or commercial. [28] Table 26 COMPARISON OF EFFECTS OF FULL FEEDING STEERS Amount of concentrate fed, per cent of ration* Days on feed Number of animals Daily intake of concentrate, pound Initial weight, pound Average daily gain, pound Dressing percentage Average per cent fat in carcass t Average carcass scoret Average carcass weight, pound . Averagec orrected carcass weight, pound§ 1960-rolled barley Pasture 119 8 555 1.49 56.3 15.1 3.0 386 332 1001 134 12 12.3 560 2.63 60.0 19.8 5.7 556 555 Drylot 70 134 8 12.5 596 2.5 62.5 22.2 6.0 584 1961-ground barley Pasture 126 8 624 0.93 54.0 11.9 4.2 423 326 1001 118 12 13.5 675 2.33 61.2 23.3 7.3 594 651 Drylot 70 133 8 11.8 652 1.93 60.5 20.1 7.1 565 567 * The pasture plus barley and drylot steers were implanted with 30 mg of diethylstilbestrol at the start of the trial, t Average per cent fat in a choice carcass = 23.6. t 9 = average choice, 6 = average good, 3 = average standard. § Corrected to a carcass weight equivalent to a carcass containing 1.297 kcal per pound, 17.3 per cent protein and 20 per cent fat. 1 1ncludes barley only. concentrate represented more energy than gains of steers not supplemented or sup- plemented for only the last half of the experiments. This occurred even though weight gains were the same. Variations in the quantity of concentrate supplementa- tion produced a similar result. Weight gains did not increase above a certain amount of supplementation but energy gains did increase resulting in higher yield and better carcass grades. It was also con- cluded that supplementation of pure al- falfa with high energy concentrates is nec- essary to produce optimum fattening of beef steers resulting in choice carcasses. LIMITED SUPPLEMENTATION OF IRRIGATED PASTURE The limited feeding of ground barley to steers grazing irrigated pasture was studied. The intake of the barley was controlled by mixing salt with the barley. The results obtained (table 23) showed that an in- creased daily gain could be obtained along with improvement in dressing percentage and carcass grade. The additional intake of barley above pasture did not, however, produce a "choice" animal at the end of the feeding period. FULL FEEDING" ON PASTURE For the production of acceptable carcasses from cattle grazing irrigated pastures a simplified approach in feeding of the grain supplement was tried. In addition to the pasture, barley was fed free choice. This comparison was made each year to a group receiving only irrigated forage and to one receiving in the feedlot a 70 per cent con- centrate ration. The stocking rate, over normal carrying capacity with no supple- ment, was doubled to 5.4 head per acre. Table 26 gives the results obtained during two different years using both ground and rolled barley. It is difficult to compare years, but it was concluded that either physical form of the barley proved satisfactory for fattening the cattle. Another aspect of these trials was that the animals receiving barley free choice in addition to the pasture, upon slaughter, showed no signs of "yellow" fat in the carcasses. An additional trial was conducted using these same pastures with a comparison of rolled milo vs. rolled barley for pasture fattening of cattle. No differences were found between the different treatments (table 27). The pasture [29] Table 27 PASTURE VS. DRYLOT FATTENING OF STEERS Ration Rolled barley plus pasture Rolled milo plus pasture 70 per cent concentrate drylot ration Number of days on feed Number of animals Daily intake of concentrates, pounds Initial weight, pounds Average daily gain, pounds Dressing percentage Average per cent carcass fat Average carcass gradef Average 20 per cent fat corrected carcass, poundst 150 6 13.7 631 2.34 60.9 23.1 7.0 652 150 6 13.4 628 2.37 61.1 22.9 7.1 652 144 7 12.2* 601 2.44 62.1 21.8 7.2 622 * Animals consumed 17.4 pounds per day total ration. t USDA grade, 7 = high good. t Corrects carcass weight to 1,297 kcal per pound, 20 per cent fat and 17.3 per cent protein. steers consumed slightly more grain than the drylot steers but had a slightly lower dressing percentage. The pastured animals had slightly higher fat content in their carcasses so when the carcass weights were corrected to a 20 per cent fat basis to give a more correct comparison between treat- ments, these differences are no longer evi- dent. There was no difference in final car- cass grade. At slaughter no sign of "yellow" fat in the carcasses was noted. It was con- cluded that either rolled or ground barley or rolled milo was acceptable when full- fed with pasture. From the results obtained the following recommendations are set forth: (1) a high- producing but palatable pasture contain- ing a mixture of legumes and grasses is needed; (2) the usual stocking rate of the pasture can be doubled; (3) the desired grain can be fed free-choice and kept con- stantly available after a three-week period in which the animals are brought on feed; (4) cattle should be rotated among fields within the pasture to keep the forage pa- latable and to facilitate irrigation; (5) control of internal parasites is necessary; (6) since this is a high-energy ration an in- creased daily gain can be expected with a 30-milligram implant of diethystilbestrol. Use of this system should result in the cattle consuming from 10 to 15 pounds of grain plus enough pasture to gain between 2.25 and 2.75 pounds daily and reaching acceptable slaughter condition in 120 to 150 days. Because of the limited length of most pasturing seasons the starting weight of the cattle should be 700-750 pounds in order to finish at 1,000-1,050 pounds live weight. ENERGY REQUIREMENTS FOR GRAZING Various estimates have been made for the energy needs of grazing animals in relation to drylot feeding. Reid et al. (1958) esti- mated that as much as 3.4 pounds of TDN is needed for grazing animals above the amount needed for animals confined to a barn. Greenall (1959) found that grazing wether lambs had a greater energy require- ment than suggested by standard values. It is difficult to obtain information on energy requirements of grazing animals. As it is possible to measure feed intake of grazing animals and also the energy con- tent of the weight gain an experiment to measure requirements of grazing and non- grazing steers was conducted. Body composition and forage intake were available from a previous experiment where five lots of steers grazed irrigated pasture at various stocking rates (table 28) (1.35, 2.25, 3.06, 3.93 and 4.68 steers per acre), making rates of gain from 0.80 to [30] Table 28 INFLUENCE OF STOCKING RATE ON STEER PERFORMANCE AND INTAKE Item Number steers per lot Steers per acre Average daily gain, pounds Average daily intake, pounds DM Lot 1 3 1.35 1.81 16.9 Pasture Lot 2 5 2.25 1.72 14.5 Lot 3 7 3.06 1.44 13.8 Lot 4 9 3.93 1.31 12.7 Lot 5 11 4.68 0.80 13.2 Soilage Lot 6 3.24 1.49 18.0 1.81 pound per day. One lot of steers was fed soilage from the same pasture and served as a nongrazing control fed in dry- lot, having a reduced activity because of confinement to a small lot (50x50 feet). A behavior study was included to deter- mine activity of the various lots. Four 24- hour observation studies were made dur- ing a typical grazing period of one week on days 1, 3, 5 and 7 that the animals were in the field. Observations were made every 15 minutes during the 24-hour day on the number grazing, standing and lying. ENERGY REQUIREMENTS COMPARED As the stocking rate increased, food and energy intake, weight gain and energy re- tention decreased (figure 7). It was shown in the production data (table 28), and with the measurement methods used in this experiment, that the maintenance requirement for grazing steers was not greatly different from non- grazing steers. When digestible energy in- take per unit of W 3 /* pounds was plotted against energy gain for the steers in this experiment and compared to those fed in a drylot (1959) no differences in the slopes of the lines were observed, giving evidence of no differences in digestible energy needs per unit of energy gain (figure 12). The elevations of the lines were not statistically different either and therefore do not give evidence of a difference in the mainten- ance requirement between the grazed steers and steers fed in drylot. It is suggested by these data that the extra activity involved in grazing on ir- rigated pasture does not result in a mea- surable increase in digestible energy re- quirements. BEHAVIOR It was shown in the behavior study that three times as much time was spent eating (grazing) — 12.2 versus 4.2 hours — by the steers on pasture than those on soilage. It might be assumed from this that greater activity was required for grazing than eat- ing soilage. Significantly more time was spent idling, either standing or lying, by steers fed soilage than by those grazing. As the stocking rate was progressively in- creased from lot 1 through lot 3 signifi- cantly more time was spent grazing and less time standing or lying, undoubtedly because of the greater competition for for- age as grazing intensity increased. This was only true up to a point under a rotational grazing system, and the steers reached a point where they did not increase grazing time although the forage available was quite limited. The study also revealed that this greatei activity did not result in in- creased measurable energy requirements for grazing. 200 i r- — Y = 88.9 + 22 6X (This experiment) r = 0.83 1 ■ ~ — Y= 77.2 +62.IX (Gorretl, 1959) 1 ^^ i# • = Lot number ^150 2 ^ a: ««• z \ ^^ J ^ m ^^ -»" en ^^ ^ "' ^ 100 ~ ^^^ """ - 1 1 I ENERGY GAIN (MECAL PER DAY) Fig. 12. Regressions of digestible energy intake on energy gain for grazing steers. [31] COMPENSATORY GROWTH It has generally been accepted that contin- uous growth is the most economical sys- tem for growing and fattening steers (Wil- son and Osbourn, 1960). Research work has shown that when cattle are restricted in growth during the winter they will gain weight more rapidly than control animals after being turned onto summer range (Bohman, 1955). (An animal whose growth has been retarded exhibits, when restric- tion is removed, a rate of growth greater than that which is normal in animals of the same chronological age. This abnor- mally rapid growth relative to age is termed "compensatory growth.") The abil- ity of the animals to compensate for low winter gains appears to be influenced by several factors: the age of the animal, the severity of winter growth retardation, and the quantity of feed available during the summer. Also in these trials, weanling cat- tle at the end of the summer grazing season were not able to catch up in total body weight to control animals, while yearling cattle were able to compensate for low win- ter gains. Optimum wintering feeding rates for calves typical of animals raised in southern Oregon has also been investi- gated. It has also been shown that irrigated pasture is a good growing ration, but that it is not sufficient to produce a finished animal. The use, however, of irrigated pas- ture or in general grazed forage to help diversify and balance feed production has long been practiced. Therefore, the role of irrigated pasture in a growing and sub- sequent fattening regime of beef cattle was explored. The plane of nutrition dur- ing winter is not ignored, and its effects on the utilization of pasture and subse- quent performance is also reported. WINTERING AND PASTURING FOR COMPENSATORY GROWTH Weanling steers were allotted at random to a fattening ration or a growing ration. The growing ration was either long or pel- leted hay and was fed in group pens (full- fed on pellets and limited-fed on long hay). Following the growing period some were fattened; others grazed irrigated pastures consisting of a mixture of orchardgrass and ladino clover. From results of previous trials, a 7-day grazing period followed by a 35-day recovery interval between grazings was practiced. Energy intakes were varied by varying stocking rates on the irrigated pasture. Fattening was done by feeding a 70 per cent concentrate ration to individ- ually fed steers. At the end of each feeding treatment, representative animals were slaughtered to determine body composi- tion and carcass characteristics. All animals were weighed every 28 days after an over- night stand without feed or water. During the growing phase of 172 days, the steers fed the pelleted hay consumed 15.8 pounds of dry matter and gained 1.76 pounds per day, exceeding the daily feed intake of 10.2 pounds and daily gain of 0.77 pound per day made by the steers fed on long hay. This resulted in the ani- mals going into the pasture phase different in body composition because of the win- tering treatment. The three different stocking rates used resulted in three separate energy intakes on irrigated pasture (table 29). Forage data obtained on this trial showed differ- ential seasonal production of forage dry matter. The heavier stocking rate de- creased the forage available by the end of the grazing season. The heavier stocking rates also favored legumes while the lighter stocking rates tended to favor grasses. Forage production of each pasture was equal each season at the start of these trials, regardless of the previous year's treatment — no significant differences were found in the initial sampling at that time. The chemical analysis of the forage avail- able showed a decrease in lignin and an increase in crude protein as the stocking rate increased. This indicates that the ani- mals were offered a more nutritious forage when the pastures were more heavily grazed, mainly because the forage was less mature due to a slower recovery rate. In contrast, the dry-matter digestibility was lowered as grazing intensity increased. A heavy stocking rate forced the animals to consume more of the coarser portions of [32] Table 29 STEER RESPONSE TO PASTURE TREATMENTS FOLLOWING TWO WINTER FEEDING SYSTEMS Growing phase — energy intake Medium* Lowf Pasture phase — energy intake Liberal Medium Low Liberal Medium 124 124 124 124 12 18 12 12 3.6 5.4 1.8 3.6 15.3b 11. 6« 18.0» 14. 5 b 0.84° 0.41d 1.67» 1.26 b 803 749 737 683 18.2 28.3 11.0 11.5 55.2 55.0 53.8 53.8 12. 9* 11.2*b 12.1* 10.3ab 2.0 1.6 1.5 1.2 0.29» 0.27» 0.27a 0.26a Low Day on pasture Number of animals Animals carried/acre Daily feed, pounds (dry basis) § . Average daily gain, pounds§ Final weight, pounds Feed consumed/pounds gain Carcass data Dressing percentage Fat percentage! Marbling score? Backfat, inches§ 124 12 1.8 18.1a 1.15b 832 15.7 58.2 16.5" 2.5 0.42° 124 18 5.4 12.6° 0.85- 659 14.8 54.2 9.0b 1.1 0.14b * Previous daily gain — 1.76 pounds; feed intake — 15.8 pounds; carcass fat — 14.3 per cent; marbling score — 2.6; backfat — 1.0 inch; in 172 days. t Previous daily gain — 0.77 pound; feed intake — 10.2 pounds; carcass fat — 7.2 per cent; marbling score — 1.0; backfat — 0.26 inches; in 172 days. t USDA grade — 1 devoid, 2 practically devoid, and 3 trace. § a, b, c, d. Means on the same line having the same superscript do not differ significantly. the forage, even though the entire plant was initially lower in lignin. Compensatory growth of the cattle oc- curred since all steers previously fed the low-energy intakes during the growing phase made greater rates of daily gain on pasture than those previously fed the me- dium-energy intakes (table 29). This com- pensatory growth resulted in approxi- mately 0.4 pound increase in daily gain when steers had previously been fed a low- energy diet. The different grazing inten- sities were for 124 days for all lots, and even with compensatory growth, carcass differences were obtained. The carcass traits improved at all levels of grazing in- tensity for those previously given the low- energy intakes during winter when com- pared to those from the medium-energy wintering ration. Fat content, marbling score, and backfat thickness improved dur- ing the grazing period, even for those steers on a medium- and low-energy intake from grazing. Consumption of forage per ani- mal decreased as the stocking rate in- creased, resulting in decreased production per animal. The production-per-unit area (figure 13), a more realistic evaluation of [33 grazing, shows that consumption per acre increased even though it decreased per animal. Live weight gain per acre increased to the medium-grazing intensity and then leveled off for those animals given the low- energy intakes during winter while it in- creased to the medium-energy intake and then declined for those receiving the me- dium-energy wintering treatment. Carcass gain per acre increased for those from a low-energy wintering ration, and declined for those previously fed a medium-energy ration. Considering all of the data it ap- pears that some latitude is available in a choice of stocking rates for animals pre- viously fed a low-energy wintering ration. This is not true for the steers previously fed a medium-energy intake, as carcass gain per acre decreased with each subsequent increase in stocking rate. It, therefore, ap- pears that best utilization of irrigated pas- ture by growing beef steers results from animals which have previously been on a low plane of nutrition. COMPENSORARY GROWTH IN THE FEEDLOT Rapid rates of gain were attained during the fattening period following pasture ] Sv4Sfft/£-#r TO tot/ £4f£M£» /A/TA££ 5vasfft//A/r to /rsv/v* £Aif- w © cm o ,-i o »« CM ,H a -Q JS o> ,-h (S CM s CO J3 tH rd O « CO OO CO O H t> OO 4> .M bfl „Q d 03 CO OS CO O CO ^ w OS ^H © o »0 CM >> CD 9 03 03 0) d a 03 >. >> A 1 .5? oo a o »o ■**" © co .-< os t~ t- M 8 0> N N N Ol N — h CO ^f O CO d s o3 ffi T»< -4 -1 O — 4 OS CO - CM t^OCOlOCO — 4 OS OS CO © >« 0O ©•"#!© CO I- -4 — i lO CM O o 03 Ph o a a J3 lO _D OS CO OS .5? -3 h to o m oo m a CD W t~ ,-4 CO o >« CM _3 -3 a S -O a x © .O CM OO -«J< i« V M J3 44>oOI>- B b s f ■ T c : c C • $ u d = h V ays on high en umber of anim aily feed, poun verage daily ga nal weight, po ;a perce ntage score inche arcass da1 Dressing Fat perce Marbling Backfat, Final gra P !z c > s O CD <»s -.S T3 m MB _cd — ^ 3 1 1 1 1 . 03

5i 2j '4J M MTJ B g^PP 03- Table 31 STEER RESPONSE— VARIOUS FEEDING METHODS, SUMMATION High Growing phase — energy intake Medium Low Item Pasture phase — energy intake Liberal Medium Low High Liberal Medium Low Fattening phase — energy intake High High High High High High High High High 222 2,471 1,059 30 1,964 46 296 1.511 3,365 69 2,228 37 358 817 5,307 87 2,598 35 367 987 5,039 84 2,588 33 367 980 4,580 82 2,518 33 321 1,826 2,536 58 2,179 39 388 1,276 4,539 78 2,562 35 397 1,434 4,169 74 2,555 34 398 Concentrates, pounds Roughages, pounds 1,501 3,959 72 Net energy required, megcals Energy for growth and fattening, per cent 2,501 32 In these trials the main difference be- tween the various systems of growing and fattening was in the length of time re- quired for steers to reach market condition and the proportion of the total energy required which was used for growth and fattening above maintenance (table 31). It would, therefore, seem that the system to use must be based on relative cost of roughage and concentrates, market condi- tions, and the length of feeding period desired. REASONS FOR COMPENSATORY GROWTH From these trials information is available to explain in part the reasons for com- pensatory growth and its influence on the efficiency of feed utilization during refeed- ing. The data suggest two explanations: (1) an increase in feed capacity (the daily feed intake per unit of metabolic body weight); and (2) an increase in the effici- ency of energy utilization independent of feed intake. ROLE OF IRRIGATED PASTURE IRRIGATED PASTURE AS AN ENERGY SOURCE High producing irrigated pasture as the entire ration is both an energy and a pro- tein source. The relative value of irrigated pasture in California compared to barley and alfalfa hay as energy sources and al- falfa hay and cotton seed meal as protein sources is shown in table 32. In this case irrigated pasture as an energy source was 60 per cent less expensive than barley and alfalfa hay during the last 10 years in California, while it was 51 per cent less ex- pensive than cottonseed meal as a protein source. Yet, the number of cattle in feed- lots fed harvested grains and forages in- creased in the past 10 years while fewer are carried on irrigated pasture. An experiment was conducted whereby irrigated pasture was compared primarily as a sole energy source, as an energy source in conjunction with feedlot fattening, and a supplemental feed (source of protein, minerals, vitamins and fiber) to barley grain as the primary energy source. All are then compared to feedlot fattening on harvested feeds. The cost study on these data merely ap- [36] Table 32 RELATIVE VALUE OF IRRIGATED PASTURE IN CALIFORNIA Energy source Protein source Pasture* Barleyf Alfalfa hayf Pasture Alfalfa hayf Cottonseed mealt acre 76.40 1.6 ton 56.33 3.9 ton 32.80 4.0 acre 76.40 4.1 ton 32.80 10.7 ton 70.60 Value per megcal. Value per pound 8.5 * Irrigated pasture stocked at 3.9 steers per acre. (Hull et al., 1961). Cost data calculated from Peterson et.al., 1959 and considered to be representative of the 1951-61 pasture cost. t Ten-year average prices 1951-61 in San Francisco. Federal-State Market News Service, 1961. j Recent average cost figures are not available but the relative relationships have not changed even if prices have. plied the 10-year average prices of har- vested feeds for 1951-61 (Federal-State Market News Service, 1961) and pasture costs for 1951-61 (Peterson et al, 1959). Pasture cost was only feed cost, and does not include animal management or non- feed expense. Response of animals (table 33) indicates that pasture of good quality did not pro- duce live weight gains equivalent to those fed on a feedlot ration high in concentrate unless carbohydrate concentrate was fed with the pasture. Energy gains, moreover, showed greater differences than indicated by weight gains. Carcass fat content was approximately 21 per cent when maximum quantities of concentrate were fed while the fat content of those given pasture only was 1 1 per cent. Grade and marbling score gave confirmatory results. The animals fed in the feedlot following pasturing made a greater daily weight and energy gain than did those fattened im- mediately whether on pasture or in the Table 33 PRODUCTION FROM PASTURE UTILIZED AS AN ENERGY AND SUPPLEMENTAL FEED SOURCE BY STEERS Number of animals Number of days Daily gain, pounds Final weight, pounds Daily feed, pounds Daily energy gain, megcals Carcass data§: Weight, pounds Fill, pounds! Fat, per cent |J Grade score** Marbling score tt Pasture followed by feedlot Pasture* 16 122 1.08 731 14.4 0.70 399 83 11.0 3.5 1 Feedlot* t 3.19 1,006 19.4 6.83 68 21.6 5.9 4.1 Pasture fattening 24 112 2.48 896 12. 1% 5.18 554 23 21.1 6.2 3.2 Feedlott 122 2.26 898 16.9 4.69 553 27 21.2 6.6 4.5 * After 122 days on pasture, eight steers were slaughtered for carcass data and eight were fattened in the feedlot for 88 days. t Fattening ration contained 20 per cent alfalfa hay, 10 per cent oat hay, 63.5 per cent barley, 3.5 per cent cotton- seed meal, 2.0 per cent molasses, 0.5 per cent oyster shell, and 0.5 per cent salt. % Barley only. § Representative steers sacrificed before the trial began contained 11.3 per cent fat in the carcass, 52 pounds of fill, and the carcass weighed 341 pounds. 1 Estimated by the method of Lofgreen et al. (1962). || Initially the carcasses contained 11.3 per cent fat. ** USDA grade — 3 average standard, 6 average good, 9 average choice, tt USDA grade — 1 devoid, 3 trace, 4 slight, 5 small. r 37 1 Table 34 COST STUDY ON PASTURE UTILIZED AS AN ENERGY SUPPLEMENTAL FEED SOURCE FOR STEERS * 3 . 5 steers per acre stocking rate, t 7 . steers per acre stocking rate. t Carcass weight corrected to 20 per cent fat and 17.3 per cent protein (Meyer et al., 1960). Pasture followed by feedlot Pasture fattening! Feedlot Pasture* Feedlot Total 14.31 54 27.5 10.9 46.76 329 14.2 16.9 61.07 383 15.9 15.0 6.55 44.53 51.08 322 15.8 18.5 56.36 56.36 322 Cost per pound carcass gain, cents Cost per pound of live weight gain, cents 17.5 20.4 feeedlot. A successful attempt was made to finish all steers to equivalent fat content and carcass grade. All animals which were fattened in the feedlot or on pasture had equivalent fat content, grade, and mar- bling even though the animals fed in the feedlot following pasturing attained a much larger live weight to fiinish at ap- proximately the same fat content. A cost study on the various methods used in fattening steers was primarily com- pared on feed costs per carcass gain where- by initial carcass weights (representative steers slaughtered initially) are subtracted from final carcass weights (table 34). The carcass weight of the animals prior to the beginning of the trial and at the end of each phase was corrected to one equivalent containing 20 per cent fat and 17 per cent protein (Meyer et al., 1960). This allowed correction for differences in fill and pro- portion of fat in the gain. It also corrects for differences in final values since it is assumed that all carcasses containing 20 per cent fat, which is midway between good and choice under the present grad- ing system, would be of equivalent value. In this case, the most expensive carcass gains were those produced on pasture, pri- marily because of the greater fill (lower dressing percentage) in the steers and the lower fat content in the weight gain. The feed cost of the carcass gain in the feedlot for the 88 days following the pas- ture period was low (14.2 cents) because the animals made a larger daily weight and energy gain. This can be considered an effect of compensatory growth since the daily gain was 3.19 pounds (table 33) while those fattened on pasture or in the feedlot gained 2.38 and 2.88 pounds, respectively, during the comparable 88-day period. It appears, therefore, that pasture which may produce a low rate and expensive gain as a sole energy source has an additional ad- vantage which should be considered — its influence on compensatory growth in the feedlot following pasturing. The total feed cost of the carcass gain for steers pastured for 122 days followed by a feedlot fattening of 88 days was 15.9 cents, approximately equal to that from those fattened on pasture. This indicates that the producer can use either system to advantage. Irrigated pasture, therefore, has a further role to economically feed and hold animals as a leveling method to even the supply of feeders to the feedlots. In addition, a larger live weight was produced when steers were pastured and then feed- lot fattened to produce the same degree of fatness. This may have advantages under certain market conditions. Cost figures calculated per pound of live weight gain (table 34) showed that pasture gains on a live weight basis were by far the least expensive when pasture was the only source of feed. This was not apparent when considering carcass gain corrected to equal fat and protein content. When cal- culations were made on live weight gain only, undue credit was given to animals having a larger fill in the gastrointestinal tract and less fat in the weight gain. This was apparent also when cost per pound of live weight gain in the feedlot following [38] pasture was compared to those fattened on pasture or in the feedlot. Economic con- siderations based on live weight gain, therefore, can produce erroneous results and it is suggested that economic studies made on growing and fattening animals consider using some equivalent measure such as fat corrected carcass. Table 32 indicates that the net energy cost in California during the last 10 years was much cheaper from irrigated pasture than from the harvested feeds. Yet, data from table 34 indicates that pasture was the most expensive source for carcass (en- ergy) gain. A study of the net energy re- quirements for maintenance and gain (table 35) indicates that 87 per cent of the net energy requirements for cattle fed on pasture only was for maintenance, while only 45-52 per cent of the energy require- ment was for maintenance in the feedlot. The total cost per unit of net energy for both maintenance and gain, was less ex- pensive from pasture than from the har- vested feeds, but if the cost per unit of net energy required for gain was used as a base, pasture was the most expensive energy source. Irrigated pasture can be economically used as an energy source of feed when compensatory growth which subsequently occurs in the feedlot is considered. In this case, the cost per unit of carcass gain was equivalent to those fattened immediately on pasture. A rancher, therefore, has a choice between these two systems in utiliz- ing irrigated pasture. One system allows him to carry animals without purchasing harvested feeds, but if he is to get the most from his pasture he should retain owner ship and fatten the steers for the compen- satory growth which occurs in the feedlot following pasturing. In this case when animals were pastured, followed by feedlot fattening, the pasture charge could increase S7.87 per animal, $27.54 per acre, or $45.90 per season, to make the cost per unit of carcass gain equivalent to that obtained when steers were fattened immediately in the feedlot. This would allow a 60 per cent increase in pasture charges. IRRIGATED PASTURE AS A PROTEIN SOURCE The feed cost per pound of carcass gain was 17.5 cents for those fattened immedi- ately in the feedlot, while those fattened immediately on pasture produced a gain which cost 15.8 cents. In the latter case, the pasture replaced primarily the supple- mental feeds, cottonseed meal, molasses, alfalfa hay and oat hay, which were sources of protein, minerals, vitamins and fiber. When pasture was the only source of en- ergy, the carcass gains cost 27 cents. From this it might be tentatively concluded that pasture fills its best role as a supplemental feed source rather than as an energy source because steers full-fed an energy source (barley) on pasture produced more inex- pensive carcass gains compared to those fattened in the feedlot (table 35). The pas- Table 35 ENERGY UTILIZATION AND COST FOR STEERS Pasture followed by feedlot Pasture fattening Feedlot Pasture Feedlot Total Net energy* for maintenance, megcals for gain, megcals 558 85 590 601 1,048 686 564 580 617 572 643 87 2.22 16.83 1,091 45 4.28 7.78 1,734 60 3.52 8.90 1,144 49 4.46 8.80 1,189 Maintenance requirement, per cent Cost per megcal. net energy: Total, centsf 52 4.74 9.85 * Based on requirements given by Garrett et al. (1959). t Cost for net energy used for both maintenance and gain. j Cost for net energy used for gain only. r 39 1 ture charge would have to increase by fattening directly in the feedlot. This $5.28 per animal or $36.96 per acre to would be an increased charge of 81 per make pasture fattening as expensive as cent or $61.60 per season for pasture. REFERENCES Blaser, R. E., J. R. Harlan, and R. M. Love 1962. Grazing management. Pasture and Range Research Techniques. Comstock Publishing Assoc, Ithaca, N. Y., p. 11. Bohm an, V. R. 1955. Compensatory growth of beef cattle: the effect of hay maturity. Jour. Anim. Sci. 14:249-55. Cole, H. H., and J. M. Boda 1960. Continued progress toward controlling bloat. A Review. Jour. Dairy Sci. 43:1585-1614. Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11:1-42. Federal State Market News Service 1961. Market and farm price averages on hay, grain, feed and butter in California. (Historical series), Sacramento, Calif. Garrett, W. N., J. H. Meyer, and G. P. Lofgreen 1959. The comparative energy requirements of sheep and cattle for maintenance and gain. Jour. Anim. Sci. 18:528-47. Greenall, A. F. 1959. Studies of grazing of crop forages by sheep. III. Intake, maintenance and weight gain requirements of wethers grazing rape. New Zealand Jour. Agr. Res. 2:639-48. Hull, J. L., J. H. Meyer, G. P. Lofgreen, and A. Strother 1957. Studies on forage utilization by steers and sheep. Jour. Anim. Sci. 16:757-65. Hull, J. L., G. P. Lofgreen, and J. H. Meyer 1960. Continuous versus intermittent observations in behavior studies with grazing cattle. Jour. Anim. Sci. 19: 1204-07. Hull, J. L., J. H. Meyer, and R. Kromann 1961. Influence of stocking rate on animal and forage production from irrigated pas- ture. Jour. Anim. Sci. 20:46-52. Hull, J. L., J. H. Meyer, and G. P. Lofgreen 1960. Effect of recovery interval of irrigated forage on the performance of grazing steers. Jour. Anim. Sci. 19:981-990. Hull, J. L., and J. H. Meyer 1962. Full supplementation — a new method of fattening beef cattle on pasture. Calif. Agric. 16:12. Hull, J. L., and J. H. Meyer 1963. Milo equal to barley for full supplementation of beef cattle on irrigated pas- ture. Calif. Agric. 17:7. Hull, J. L., J. H. Meyer, Sergio E. Bonilla, and W. Weitkamp 1965. Further studies on the influence of stocking rate on animal and forage produc- tion from irrigated pastures. Jour. Anim. Sci. 24:697-704. Hull, J. L., J. H. Meyer, and C. A. Raguse 1966. Studies of rotation and continuous grazing using beef steers. Jour. Anim. Sci. 26:1160-64. Ittner, N. R., G. P. Lofgreen, and J. H. Meyer 1954. A study of pasturing and soiling alfalfa with beef steers. Jour. Anim. Sci. 13:37-43. 2 The findings reported in this bulletin, where the reference is not cited but listed, were com- bined to form the basis for this publication. T401 Kromann, R. P., J. H. Meyer, and J. L. Hull 1961. Energy requirements of grazing steers. Jour. Anim. Sci. 20:450-53. Lofgreen, G. P., J. H. Meyer, and J. L. Hull 1957. Behavior patterns of sheep and cattle being fed pasture or soilage. Jour. Anim. Sci. 16:773-80. Lofgreen, G. P., J. H. Meyer, and N. R. Ittner 1960. Effects of time and level of supplementation on beef steers fed alfalfa soilage or hay. Jour. Anim. Sci. 19: 156-63. Lofgreen, G. P., J. H. Meyer, and M. L. Peterson 1956. Nutrient consumption and utilization from alfalfa pasture, soilage and hay. Jour. Anim. Sci. 15:1158-65. Lofgreen, G. P., J. L. Hull, and K. K. Otagaki 1962. Estimation of empty body weight of beef cattle. Jour. Anim. Sci. 21:20-24. Martin, W. E., V. V. Rendig, A. D. Haig, and L. J. Berry 1965. Fertilization of irrigated pasture and forage crops in California. Calif. Agric. Exp. Sta. Bui. 815. Meyer, J. H., G. P. Lofgreen, and W. N. Garrett 1960. A proposed method for removing sources of error in beef cattle feeding experi- ments. Jour. Anim. Sci. 19: 1 123-31. Meyer, J. H., G. P. Lofgreen, and F. K. Hart 1953. The value of certain supplements for beef cattle fed harvested green alfalfa. Jour. Anim. Sci. 12:806-11. Meyer, J. H., G. P. Lofgreen, and J. L. Hull 1957. Selective grazing by sheep and cattle. Jour. Anim. Sci. 16:766-72. Meyer, J. H., G. P. Lofgreen, and N. R. Ittner 1956. Further studies on the utilization of alfalfa by beef steers. Jour. Anim. Sci. 15: 64-75. Meyer, J. H., and L. G. Jones 1962. Controlling alfalfa quality. California Agric. Expt. Sta. Bui. 784. Meyer, J. H., J. L Hull, W. H. Weitkamp, and S. Bonilla 1965. Compensatory growth responses of fattening steers following various low energy intake regimes on hay or irrigated pasture. Jour. Anim. Sci. 24:29-37. Peterson, M. L„ and R. M. Hagan 1953. Production and quality of irrigated pasture mixtures as influenced by clipping frequency. Agron. Jour. 45:283-87. Peterson, M. L., V. P. Osterli, and L. J. Berry 1959. Managing irrigated pastures. Calif. Agric. Exp. Sta. Cir. 476. Reid, J. T., P. G. Woolfolk, W. A. Hardison, C. M. Martin, A. L. Brundage, and R. W. Kaufman 1952. A procedure for measuring the digestibility of pasture forages under grazing conditions. Jour. Nutr. 46:255-69. Reid, J. T., A. M. Smith, and M. J. Anderson 1958. Differences in the requirements for maintenance for dairy cattle between pasture- and barn-feeding conditions. Proc. Cornell Nutr. Conf. for Feed Manu- facturing, Nov. 12-16, pp. 88-94. Wilson, P. N., and D. F. Osbourn 1960. Compensatory growth after undernutrition in mammals and birds. Biol. Rev. 50:324-63. 10m-12,'67(H5215)J.F. [41] THE GOOD EARTH ... is the abundant earth. To achieve it, vast knowledge is needed now — and more will be required as expanding populations continue to make even greater demands upon the earth's resources. How are scientists, researchers, and agriculturists developing and implementing knowledge which will make the good earth flourish for future generations? In part, the answer will be found in the many pub- lications put out by the University of California's Division of Agricul- tural Sciences. Among these publications are: cgssssa- the BULLETIN series . . . designed for an audience of scientists, and for informed lay- men interested in new research. the CIRCULAR series intended for a popular audience, and offering extensive dis- m cussions of some phase of an agricultural ^ operation JCALIFORNIA AGRICULTURE ... a ^monthly magazine describing latest research Mn the Division of Agricultural Science, and designed for researchers, informed farmers, and agri-businessmen LEAFLETS . . . these are short circulars de- k signed to answer one or a few questions for^ the home-grower or farmer without giving^ detailed background information *:;■ mm rg^V^ m- j catalog of publications, write Agricultural Publications, 207 University Hall, University of California, Berkeley, Calif. 94720