£* 1 " K Division of Agricultural Sciences UNIVERSITY OF CALIFORNIA CROSSBREEDING OF BEEF CATTLE ill; ; :; : REUBEN ALBAUGH 6. M. SPURLOCK CALIFORNIA AGRICULTURAL Experiment Station Extension Service CIRCULAR 543 "Is crossbreeding of livestock profitable — and how can such a program be incorporated into an average ranching operation?" This circular discusses some results of research which will help answer that question. Half-Brahman calves from 2-year-old Hereford heifers. Calves are about 2 months old. JANUARY, 196^ COVER PHOTO: Angus-Hereford crossbred cows with Shorthorn-Angus-Hereford calves (three-way cross). The authors: Reuben Albaugh and G. M. Spurlock are Extension Animal Husbandmen, Davis. 2 CROSSBREEDING OF BEEF CATTLE INTRODUCTION Crossbreeding — the mating of different strains, breeds, or species — has been prac- r ticed for long periods of time in many parts of the world. With the development of highly productive hybrid strains of corn, which resulted from crossing two inbred lines, even more interest has de- veloped in hybridization of plants and animals by both laymen and scientists. When two inbred lines within a breed are crossed, the mating is referred to as a line cross or narrow cross. When a Here- ford is bred to a Shorthorn, this is a me- dium cross; but when a Hereford is mated to a bison (two species) this is a wide cross. Usually, the wider the cross the 4 more hybird vigor, although loss of fertil- ity and other problems may arise by x crossing widely different species, such as mare and jack, buffalo and cow. Crossbreeding may be desirable for in- v creasing hybrid vigor or blending the characteristics of different breeds. For j example, Brahman cattle transmit heat and insect resistance in crosses with - British breeds. Early Investigations of * Crossbreeding Beef cattle are not crossbred as exten- sively or systematically as are swine and » sheep, but some careful, well-planned crossbreeding is being done. At the Iowa k station, blue-gray cattle (crosses between Shorthorn and Aberdeen-Angus or Gal- loway) have demonstrated their equality or even superiority to the parent breeds as market animals (Wentworth, 1912).* >- At the Smithfield, England, show, cross- breds had a higher dressing percentage See "Literature Cited" for citations referred to in text by author and date. than most of the purebreds, and yielded a higher percentage of valuable whole- sale cuts (Hammond, 1920). In Wisconsin, Holstein-Angus cross- bred steers made satisfactory gains, com- pared with purebred steers of either of the parent breeds (Fuller, 1928). Steers of this crossbreeding were suitable for marketing. On the Gulf Coast, crosses between the Brahman and breeds of English origin showed greater weight-for-age than did the English breeds (Black, et al, 1934; Rhoad, et al., 1943). The crossbred was better adapted to the hot climate and showed greater resistance to insects and diseases. Today, cattle having three- eighths or more of Brahman blood lines perform well in those areas. Montana studies have shown that crossbred cattle had less digestive dis- turbances in the feedlot than purebreds (Phillips, et al., 1942). In Canada, crosses of yak and bison with domestic cattle showed remarkable vigor as expressed by stamina, size, longevity, and resistance to cold (Deakin et al, 1935). In Ohio experiments, crossbred calves tended to have an intermediate length of gestation where this difference existed between the two parent breeds (Rife, et al., 1943). Birth weights of purebred Angus calves were lighter than purebred Herefords, and the gestation period was 10 days shorter. Birth weights of cross- bred Angus-Hereford calves and Here- ford-Angus calves were lighter than those of purebred Herefords, and their gesta- tion periods were intermediate between parent breeds. Weaning weights were higher for the crossbred calves. The per- formance of the crossbred cow was not measured in this study. SUPERIORITY OF CROSSBRED DAMS A 9-year trial at the U.S. Livestock Ex- periment Station, Miles City, Montana, was designed to test the possibilities of maintaining heterosis (hybrid vigor — see page 12) through the use of sires from the beef breeds and of crossbred females (Knapp, et ah, 1949). The first generation cross was purebred Shorthorn bulls on purebred Hereford cows. The second generation was purebred Aberdeen-Angus bulls on crossbred Hereford-Shorthorn cows. The third generation was purebred Hereford bulls on cows that were one- half Angus, one-fourth Hereford, and one-fourth Shorthorn. Crossbred Shorthorn and Hereford steers had significantly heavier weaning and final feedlot weights than purebreds, and gained more in the feedlot. Birth weight, slaughter steer grade, and carcass grade showed no significant difference. Second generation steers which were one-half Angus, one-fourth Hereford, and one-fourth Shorthorn also had heavier weaning and final feedlot weights but did not gain more in the feedlot. Their slaughter steer grades and carcass grades were higher than for the purebred Herefords. Third generation steers, five-eighths Hereford, one-fourth Angus, and one- eighth Shorthorn, excelled the purebred Herefords in all measures of production except birth weights. The females in all three generations of crossbreeding were superior in wean- ing weights and weaning scores to pure- bred Herefords. The calf crop was about 5 per cent higher for the crossbreds than for the purebreds. The crossbred females were excellent range cows, high in fer- tility, good milkers, and produced heavy calves at weaning time. In every case crossbred steers returned a greater net profit (based on actual sell- ing price). The price differences per head per year were: 1939-40 $1.72; 1940-41 $3.39; 1942-43 $14.34; 1943-44 $10.49; 1945-46 $33.61; 1946-47 $21.33. This study did not compare purebred Herefords and crossbreds with purebred Shorthorns and Angus. Had Shorthorn and Angus females been used, differences may not have been as great because of su- perior milk production of these breeds. A typical Choice Hereford-Shorthorn crossbred steer. 4 r § One-fourth bison bul out of a hybrid cow. (Manyberries Experiment Station, Alberta, Canada. Courtesy of F. H. Peters.) TYPES OF CROSSES Bison-Cattle Crosses A herd of cattalo (domestic cattle [Bos taurus] on American bison [Bison ameri- canus]) was developed in Alberta, Canada (Manyberries Experimental Farm, 1959). All first-cross males were sterile, and fer- tility continued to be a problem in the males after generations of backcrossing and intermating. Cattalo cows were supe- rior to range Herefords in ability to graze on winter range in cold weather. Hereford calves made greater feedlot gains and had higher carcass grades. Cattalo calves were lighter at birth and made greater gains from birth to weaning (20 to 30 pounds heavier than Herefords when weaned at 6 months). The cattalo had excellent feet and were long-lived. This project has been discontinued because of fertility and temperament problems. Brahman Crosses in Canada In a test of winter hardiness of the Brah- man cattle at the Manyberries Experi- mental Farm, crossbred Brahman progeny were equal or superior to the Hereford controls in growth rate, and they wintered on the range without ill effects. Calves out of Brahman crossbred cows were smaller at birth than Herefords. None of the crossbred 2-year-old heifers needed assistance at calving time. In this study, Brahman bulls were crossed on Hereford, Angus, and Shorthorn cows, and offspring performance was compared to purebred Herefords. Performances of all three crosses were similar, but they significantly outgained Herefords in post- weaning winter and summer periods. Winter weight loss was less for the cross- breds than it was for purebreds. Charolais cross calves out of Angus mothers. Straight Angus calves also shown. Charbray and Charolais Crosses A study of the performance of Charbray, Hereford, and crossbred Charbray and Hereford steers showed the following re- sults (MacDonald, et al, 1959): "Bulls of Charbray breeding and Here- ford bulls were turned out with a com- mercial herd of Hereford cows in south- western Saskatchewan in 1956. It was assumed the cows were bred at ran- dom. At weaning in 1957, 25 Charbray x Hereford (crossbred) steers and 25 Hereford steers were selected at ran- dom, weighed, and removed to a com- mercial feedlot where they were fed in two groups to a desirable slaughter finish. "Crossbred steers were heavier at weaning, gained more per day on feed, and returned higher hot carcass weights with greater eye of loin areas than Hereford steers. There was no signifi- cant difference between groups in dressing percentage, average thickness of rib fat, TDN consumption per pound of liveweight gain, or average muscle fiber diameters of samples taken from M. longissimus dorsi. The Hereford group produced a higher proportion of choice carcasses than the Charbray x Hereford group." Charolais and Hereford Crosses Research comparing Charolais, Herefords, and crossbreds of these two groups showed that some of the Charolais have definite promise, but also indicated that care must be taken in selection of cattle because of their extreme variability (Woodward, 1960). Birth weights. Charolais and Herefords were about the same. The crossbreds were approximately 10 per cent heavier at birth, but calved with little difficulty. Weaning weights. At the same age, Charo- lais and one group of crossbreds were about 14 per cent heavier than the Here- fords. The crossbreds out of the better Charolais bull were 20 per cent heavier. Feedlot gain. The Herefords and Charo- lais were similar. The crossbreds gained 8 to 20 per cent faster. Feed conversion. There was a slight ad- vantage for the Herefords and crossbreds over the Charolais. Dressing percentage. One crossbred group dressed 1.7 per cent lower than the Here- fords. The other group of crossbreds and the Charolais were about 1 per cent higher. Carcass grade. The Herefords graded an average of low Choice. Both crossbred groups graded high Good and the Charo- lais middle Good. Carcass composition. The Charolais had about 6 per cent more lean meat than did the Herefords, but several individuals were definitely undernnished. The cross- breds had 2 to 3 per cent more lean. Typical scene of crossbred cattle in a California feedlot. > Carcass quality. One group of crossbreds was fully as good as the Herefords in cooking tests (flavor and tenderness) al- though grading lower. European Crossbreds Cattle herds in western Europe are mostly dual-purpose animals raised primarily for milk production and with beef and veal as secondary products (Carpenter, 1965), but there is a growing tendency to pro- duce crossbred animals to increase and improve carcass beef. Charolais, Angus, or Limousin bulls on black and white Friesian cows are being tried. Crossbred cows produced from Angus bulls on black and white Friesian cows are bred to Charolais bulls to produce a three-way cross slaughter animal. RESULTS OF CROSSBREEDING STUDIES A Five-year Crossbreeding Trial The results of a 5-year crossbreeding study conducted on two ranches in Glenn County are shown in table 1 (Bell, 1966). On the Stone Valley Ranch, straight Herefords and Angus-Hereford crosses were compared. The cows producing crossbred calves were younger and lower in quality than the Herefords, but their performance was similar to that of the Herefords. At the Nye ranch, first-cross Angus- Hereford calves were compared to three- way cross Shorthorn-Angus-Hereford ani- mals in weaning weight and carcass weight-per-day-of-age, carcass merit, and cutability. The three-way cross cattle out- performed the two-way cross animals in almost every measure of production. The crossbred mothers undoubtedly had a great influence on these results. Effects of Crossbreeding on Puberty In Nebraska, Hereford, Angus, Shorthorn, and crossbred heifers of these breeds were used to study age and weight at puberty (Koltenback et al, 1962). These heifers represented progeny from three Angus, four Hereford, and four Shorthorn bulls. The bulls were bred to females of their own breed and to cows of each of the other two breeds (table 2, page 8). Table 1 NYE AND STONE VALLEY RANCH STUDY 8 Nye Ranch Stone Valley Item Hereford X Angus Shorthorn X Angus-Hereford Hereford Angus X Hereford Steers: 24.0 5.6 566.0 88.5 2.00 24.0 557.0 88.1 2.14 20.0 2.13 1.38 73.0 11.6 0.43 50.6 116.0 3.7 604.0 88.4 2.18 117.0 573.0 88.1 2.17 92.0 2.34 1.46 92.0 11.0 0.54 49.3 281.0 5.6 522.0 86.6 1.83J 281.0 507.0 86.5 1.84 164.0 2.33 1.33 60.0 11.2 0.41 50.3 137 Cow age 3.8 502 Weaning grade Adjusted average daily gain (lb.) f Heifers: 87.1 1.77 138.0 464.0 Weaning grade Adjusted average daily gain (lb.)t Carcass data: (steers) Number of calves 86.1 1.75 66.0 2.35 Weight per day of age, carcass (lb.) Per cent Choice 1.34 72.0 11.9 0.50 50.3 * All cattle run together after calves were 6 months of age. t Adjusted for age of dam, and age and sex of calf. t Fastest gaining males saved for bull prospects are not included. Effects of Crossbreeding on Calving Problems Table 3 shows results of a Montana Ex- periment Station study comparing the age at puberty and size of pelvic opening of Table 2 AGE AND WEIGHT OF CALVES AT PUBERTY IN UNIVERSITY OF NEBRASKA STUDIES Breed Number Age at Weight at of heifers puberty puberty months pounds Straightbred : Angus 16 13 524 Hereford 12 12 16 14 615 Shorthorn 510 Crossbred : Angus-Hereford and Hereford- Angus 13 13 550 Angus-Shorthorn and Shorthorn-Angus. . . . 17 12 504 Heref < ird-Shorthorn and Shorthorn-Hereford 17 12 514 straightbred cattle and crossbreds (Klos- terman, et ah, 1966). Because the cross- bred female is hardier than the straight- bred and has a larger pelvic opening, few calving problems occur with a first-calf crossbred heifer. This also has been ob- served by cattlemen calving commercial 2-year-old crossbred heifers. Effects of Crossbreeding on Conception Rate Workers at the University of California Experiment Station in Davis studied con- ception rate of crossbreds and straight- breds of the Hereford, Angus, and Short- horn breeds (Carroll, 1966). The Angus- Hereford cross showed heterosis of 9 per cent for conception rate, Hereford-Short- horn 2 per cent, and Shorthorn-Angus 8 per cent. For live-born calf crops, the Angus-Hereford showed 17 per cent het- erosis, the Hereford-Shorthorn 3.8 per cent, and the Shorthorn-Angus 9.2 per cent. Table 3 AGE, WEIGHT AND PELVIC OPENING AREA AT PUBERTY OF STRAIGHTBRED AND CROSSBRED HEIFERS (U. S. Livestock Experiment Station, Miles City, Montana) Blood group Number Age Weight Pelvic area Straightbred : 14 16 23 34 39 2S 5 7 9 days 360 386 370 368 370 374 330 344 333 pounds 588 596 700 585 649 648 631 638 674 sq. cm. 153 Hereford Charolais Crossbred:* A XH A XC H XC A XBS H XBS C X BS 157.2 189.0 159.3 174.0 176.8 168.8 171.6 176.2 * A = Angus; Brown Swiss. Hereford; C = Charolais; BS = Effects of Crossbreeding on Appetite In a Florida trial where Shorthorn, Brah- man, and Brahman-Shorthorn crosses were used crossbreds showed increased appetite; higher average daily gains with greater feed efficiency were made by crossbred calves up to weaning age (Har- grove, et al., 1959). Effects of Crossbreeding on Milk Production Milk production of Herefords, Highland, and crosses of these two breeds were studied (Lawson, 1963). In mid-June, at the height of milk production, crossbred cows averaged 7.4 pounds, Herefords 7.2, and Highlands 6.5, for a 12-hour milk yield. By mid-August there was a decline of 2 pounds of milk per cow, and by the end of October the milk production was reduced another 2 pounds per cow for all breeds and crosses. Also at this station, cross Hereford-Brahman cows yielded more milk with a higher percentage of butterfat than the Herefords. The sea- sonal decline was less for the crossbreds. At the Texas Experimental Station in Angleton a study (Nelson, 1966) com- pared Brahman, Hereford, and crosses of the two, and got results similar to those obtained in the Canadian studies of Law- son (1963). Greater milk production from crossbred cows may explain the superior weaning weight of their calves. CURRENT CROSSBREEDING STUDIES Experiment stations conducting cross- breeding studies (Rollins, 1966) on liva- bility, growth rate, efficiency of gain, and performance of crossbred mothers com- pared to straightbred dams are listed on page 10. In general, the data being ob- tained should tell how much crossbreed- ing affects the economic traits of beef catde. The experiments are designed so that data from all stations can be com- bined; this will result in greater accuracy because large numbers of cattle represent- ing wide areas of beef production are involved. * Alabama, Georgia, Louisiana, South Carolina, Virginia; summarized in Southern Coop. Serv. Bui. 81 (Animal Husb. Res. Div., USDA, Wash.). There is a slight overlap in the data obtained from this source and those listed for Virginia. t Estimates based on knowledge of experimental designs used. Number of calves, sires, and dams involved in Angus-Hereford crossbreeding experiments Number Number Number Experiment station of calves of sires of dams California (experiment 1) 106 8 80 (experiment 2) 69 4 55 Ohio 400 9 56 Miles City 101 12 78 Nebraska 165 33 160 Virginia 119 10 70 Saskatchewan 127 10 80 Southern states* 1613 150f 236 800f Total 2700 1379 Beef cattle crossbreedin g experiments underway at experiment stations in the U. S. Type of cross Location of British British British British Brahman Charolais experiment X X X X X X station British* Brahman Charolais Dairyf Charolais | Dairy Alabama A, H, Sh H California A, H, Sh Florida A, H Georgia A, H, Sh A, H, Sh Hawaii A, H A, H Iowa H H,BS,Hol Louisiana A, H, Sh A, H, Sh A, H Br, Ch Missouri A, H A, H Miles City A, H A, H A, H, BS BS (USDA) Ohio H Texas A, H, Sh A, H, Sh A, H, Sh H, BS Br, Ch Virginia A, H, Sh * British hreeds: A = Angus; H = Hereford; Sh ~ Shorthorn f Dairy breeds: Hoi = Holstein; BS = Brown Swiss { Other breeds: Br = Brahman; Ch = Charolais The total number of cows, bulls, and calves used in Angus-Hereford studies is shown on page 9. Further studies involv- ing these and other breeds (shown in the table above) should also provide highly significant data. HETEROSIS IN RECIPROCAL CROSSES In a Nebraska experiment involving 751 calves of the Hereford, Angus, and Short- horn breeds and all reciprocal crosses, the crossbred calves showed significant het- erosis in birth weight, average daily gain, weaning weight adjusted to 200 days, and conformation score (Gregory, et ah, 1965). Heterosis is usually measured as that amount by which the crossbred exceeds the average of the two parent breeds. Table 4 UNIVERSITY OF NEBRASKA EXPERIMENTAL DESIGN (total number sires, dams and calves by subgroup) Dam* Sires | Breed Number of dams used Hereford Angus Shorthorn Total offspring 80 SO 80 240 n umber of offspring Hereford 118 66 68 252 60 115 62 237 72 65 125 262 250 246 255 TOTAL 751 ' Experiment was initiated with 80 females of each breed, and all open females were removed each year. t Sixteen Hereford, 17 Angus and 16 Shorthorn sires. The plan was to use 4 sires of each breed per year. 10 Table 5 EFFECTS OF HETEROSIS IN A UNIVERSITY OF NEBRASKA STUDY (all crossbreds and straight breds; sexes combined) Item Number Birth weight Daily gain Weight at 200 days Conformation score 393 358 pounds Crossbreds 74.2 71.5 0.5 1.816 1.732 0.084** 0.013 437.4 418.0 19.4** 2.8 10.87 10.70 0.17** 0.06 ** P < .01 However, if the cross is to be useful it must exceed the better parent breed in economic productivity. The Degree of Heterosis Depends on the Cross Heterosis may occur when some animals or breeds are crossed, but the perform- ance of the crossbred may be less than one of the parent breeds. Table 6 com- pares Herefords, Charolais, and crosses of the two breeds (Klosterman, et al., 1966). In this example the Charolais out- performed crosses and straight Herefords. If the selling price of Charolais feeder or fat animals is well below that of Here- fords or crossbreds, it may be profitable to make such a cross. Some individual animals and some breeds cross better than others. For ex- ample, at the California station Hereford- Angus calves were 5.2 per cent higher in weaning weight than straight Angus. But Angus-Hereford calves were 3.2 per cent heavier (Rollins, 1966) than straight Angus (tables 9 and 10). In this example, the Angus cow may have been a superior milk producer. Workers at the Nebraska station made comparisons of straightbred Hereford, Shorthorn and Angus with crosses be- tween these breeds (Gregory, et al, 1966). They found that heterosis effects on growth rate, feed efficiency, carcass weight, and carcass merit were greater in Hereford-Angus and Hereford-Short- horn steers than in Angus-Shorthorn Table 6 WEIGHTS AND GAINS OF HEREFORD, CHAROLAIS AND CROSSBRED CATTLE (adjusted for differences in years, sex, and systems of management) Item Hereford Charolais Crossbred Hereford and Charolais 34 68.3 453 1.49 1.07 1.21 2.07 837 1.56 538 32 85.9 613 2.03 1.36 1.24 2.31 1033 1.96 528 38 75.7 544 1.79 1.23 1.32 2.33 972 1.83 530 average Birth weight (lb.) . . 77 1 533 Average daily gain in lb. 1.76 Average daily gain on winter ration (lb.)* Average daily gain on pasture (lb.)* 1.22 1.22 2.19 935 1.76 533 Includes 51 cattle wintered and pastured prior to going on feed. 11 crosses. Heterosis effects on growth rate in crossbred heifers followed the trend shown by steers but differences between crosses were not significant. California studies (Carroll, 1966)showed greater heterosis for conception rate for the Angus-Hereford cross (17 per cent) than for the Hereford -Shorthorn cross (3.8 per cent). These examples emphasize the importance of proper breed crosses and of using superior breeding stock (especially bulls) in any crossbreeding plan. Tables 7 and 8 estimate percentages of hybrid vigor for some traits studied at several experiment stations. The great economic importance of traits in which hybrid vigor was expressed indicates the need for greater use of crossbreeding. Table 8 ESTIMATES OF HYBRID VIGOR FERTILITY AND VIABILITY EXPRESSED AS PERCENTAGES IX Experiment station Percent- age calf crop born Viability: birth to weaning Percentage calf crop weaned California (experiment 1) (experiment 2) Ohio 16.0 1.2 6.7 7.2 3.7 0.0 5.5 25.2 Miles City. 1.2 Virginia Saskatchewan 12.5 -1.6* 8.0 4.1 9.3 * Minus values straightbred. indicate comparative superiority of Table 7 ESTIMATES OF HYBRID VIGOR IN WEIGHT AND WEANING GRADE EXPRESSED AS PERCENTAGES Experiment station Birth weight Pre- weaning gain Weaning weight Weaning grade California (experiment 1) (experiment 2) Ohio -0.2* 4.5 -1.1* 3.5 2.0 4.6 4.8 5.5 5.6 4.4 7.6 3.8 4.2 4.3 5.2 4.0 1.1 -0.2* Miles City Nebraska -0.1* 2.1 -1.3* Saskatchewan Average 1.7 5.0 4.3 0.1 Southern states average 2.5 3.3 3.1 Total average . . 2.1 4.2 3.9 Calculating Hybrid Vigor The following formula is used to calcu- late hybrid vigor for each trait (Angus and Hereford crosses versus straightbreds are compared in this example): (AH + HA)-(AA + HH) AA + HH * Minus values indicate comparative superiority of straightbred. x 100 = percentage hybrid vigor. For instance, average weaning weight is 410 pounds for Angus and 390 pounds for Herefords (total 800 pounds). Weaning weight of crossbred cattle average 430 pounds for the Angus-Hereford cross and 470 pounds for the Hereford- Angus cross. Thus, 900 - 800 = 100; 100 - 800 = 0.125 x 100 = 12.5 per cent hybrid vigor for this trait. Although data for all traits are not ob- tained, table 9 shows the advantage of a Hereford- Angus cross over straight Angus. Table 10 gives the results of Angus- Hereford cross versus straight Herefords. Although these data are not complete, they do indicate the superiority of the crossbreds. 12 Table 9 COMPARISONS OF HEREFORD-ANGUS CROSSBRED CALVES WITH STRAIGHTBRED ANGUS CALVES, ALL PRODUCED IN STRAIGHTBRED ANGUS COW HERDS (values are crossbred average - straightb red average expressed as percentages) straightbred average Experiment station Calf crop born Viability: birth to weaning Calf crop weaned Birth weight Pre- weaning gain Weaning weight Weaning grade per cent pounds California (experiment 1) California (experiment 2) Ohio Miles City 6.7 9.9 5.2 12.2 17.1 14.5 10.2 2.6 7.4 3.3 9.3 3.4 8.6 4.3 3.0 0.8 6.7 7.6 12.2 13.9 4.4 6.4 1.9 Southern states average 13.5 2.4 3.9 13.7 3.8 5.2 Table 10 COMPARISONS OF ANGUS-HEREFORD CROSSBRED CALVES WITH STRAIGHTBRED HEREFORD CALVES (all produced in straightbred Hereford cow herds) Experiment station Calf crop born Viability: birth to weaning Calf crop weaned Birth weight Pre- weaning gain Weaning weight Weaning grade per cent pounds California (experiment 1) California (experiment 2) Ohio 6.7 -2.1 5.8 12.8 -5.5 -5.7 -5.1 7.3 3.6 5.6 5.6 5.0 1.9 3.6 Miles City Nebraska 1 2 -3 5 6.7 1.8 12.8 -5.4 5.5 4.0 -1 2 -7.4 4.3 2.3 -6.4 4.9 3.2 Minus values indicate comparative superiority of straightbred. 13 CROSSING INBRED LINES Not much information is available on re- sults of crossing inbred lines of beef cattle. At Havre, Montana, when inbred Here- ford lines were crossed, birth weight, weaning weight, postweaning gain, and final weaning weight were 0.1, 4.6, 4.3, and 4.7 per cent heavier than they were for straight inbred cattle (Flower, et ah, 1963). In a Colorado study weaning weights of line-cross female and male calves were 15 and 8 per cent higher than for their inbred contemporaries (Stonaker, 1963). Inbreeding percentages in the inbred-line calves and dams used in this study were 33 and 24 per cent. Inbreeding of line- cross calves and dams was 5 per cent. Inbred lines bred among themselves tend to be less productive, so these results of line crossing might have been less striking in comparison to results obtained with other non-inbred cattle. This system is not practical for commercial cattlemen be- cause inbred lines of cattle of both sexes are not widely available. More information is needed before the use of inbred lines of cattle can be com- pletely evaluated. Comparisons are neces- sarv between top crosses of inbred bulls with non-inbred females, and matings of otherwise similar non-inbred bulls with comparable cows. Data are also needed comparing progeny of such groups with crossbred calves sired by bulls of other breeds used on cows similar to those noted above. CROSSBRED BULLS There is currently little experimental in- formation on the performance of cross- bred bulls. In a Montana study of sperm production and breeding abilitv in young straight and crossbred bulls, two bulls from each of the Hereford, Angus, Charo- lais, and reciprocal crosses of these three breeds were used (Bellows, et ah, 1964). Crossbreds exhibited greater libido (sex desire), met all electroejaculation classifi- cation criteria, and produced motile sperm and reached age of first ejaculation earlier than did straightbreds. Crossbreds experienced copulation and ejaculation of sperm in adequate amounts at an earlier age than did the straightbreds. In this study, Charolais-sired cattle were the lat- est to reach satisfactory breeding ability. A Virginia studv compared perform- ance of crossbred bulls to performance of purebreds as follows: Purebred bulls were bred to purebred females of the same breed; for example, Angus x Angus. Pure- bred bulls were crossed with purebred cows of a different breed; for example, Angus x Hereford. Crossbred bulls were crossed with purebred cows; for example, Angus-Hereford x Shorthorn (Gaines, et ah, 1966). The percentage of calves weaned was used as an economic meas- urement. These data showed that the highest performance for this trait occurred when breeding purebred bulls to pure- bred cows of a different breed; the lowest occurred when purebreds of the same breed were mated. Where crossbred bulls were used on purebred cows of different breeds, calf weaning percentage was be- tween the other two. Calves sired by crossbred bulls were born 1/2 weeks earlier than calves sired bv purebreds, but birth weights were not greatlv different. This may be due to hybrid vigor, sexual maturity, libido, semen quality, or other reasons. Possible disadvantages in using cross- bred bulls include limited and irregular supply of sires. Where sires originate in a crossing program with a limited number of breeds (three, for example), two breeds would be represented in the sire, hence he would be more closelv related to females (bv breed within the crossing scheme) than a straightbred male. An example of straightbred versus crossbred sires and dams would be as fol- 14 lows: Shorthorn bull x Angus-Hereford cow; dam is crossbred, calf is crossbred. Shorthorn-Angus bull to Hereford cow; calf is crossbred but dam is not. It is likely that the crossbred male would have less effect on performance than crossbred females. Females affect offspring through milk production, moth- ering ability, and fertility. There is no known reason why high-producing cross- bred bulls of a different breed than the cow herd should not be used. Example: Shorthorn-Charolais bull x Angus-Here- ford cows. Crossing for New Breeds Examples of recognized breeds based on crossbreeding are Santa Gertrudis, Beef- master, Braford, Brangus, and Charbray. Inbreeding and linebreeding were also employed in developing these new breeds. When crossbred bulls and crossbred cows of the same cross are mated, hybrid vigor is soon lost in subsequent generations. When a new breed or strain is developed by crossbreeding, the advantage of the breed is due to the blending of qualities of the parental breeds and not to hybrid vigor alone. RESULTS OF CROSSBREEDING SWINE AND SHEEP Swine. Approximately 80 per cent of the swine sold for slaughter are crossbreds. Minnesota Experiment Station experi- ments showed that crossbred sows made excellent mothers and raised larger litters to a heavier weight at weaning time than the purebreds (Winters, et al, 1935). The crossbred pigs reached market weight at an earlier age and were excellent feeders. The three-way cross pigs were superior to the two-way crosses mainly because their mothers were crossbreds. The practice of using crossbred sows for breeding pur- poses and breeding them to a purebred boar of a different breed (making the three-way cross) is a common and profit- able one in the pork-producing section of the country. Sheep: two-way ewes. A large percent- age of lambs produced for market are crossbred. Most range sheepmen want two-way ewes — those producing a profit- able fleece and a top market lamb. Such a ewe usually is a Rambouillet, Corriedale or similar white-face breed; to produce a good market lamb, she is bred to a mut- ton breed, such as Suffolk or Hampshire. Replacement ewes are purchased from a breeder who specializes in raising range breeding ewes, or are produced on the ranch. A select group of foundation ewes and rams are chosen for conformation, quality, staple length and quality of fleece, open face, and ample size. The offspring of these superior sires and dams are kept as herd replacements. Results of various matings of Shrop- shire, Southdown, Hampshire, and Me- rino sheep showed that two-way crosses of various mutton breeds and three-way crosses, including some of Merino, out- classed the average of purebred parents in all production comparisons (Sidwell, et al. 1962, 1964). Wool-type rams in three- way crossings increased quality and pro- duction of wool significantly and did not materially lower carcass quality. CROSSBREEDING CATTLE: THEORY, PRACTICE The genetic basis of the heterosis ob- tained by crossing breeds or inbred lines is not completely understood. One pos- sible explanation is that many of the genes influencing economic traits are dominant. No one breed has all of the desirable 15 dominant genes, but different breeds are probably homozygous (pure) for different genes. Animals resulting from the cross of two breeds will, therefore, carry a larger number of favorable genes than either parent; the result is a superior ani- mal. Another possibility is that superior performance is a direct result of hetero- zygosity (different genes from the two parents). Traits of low heritability may have a higher heterosis than those of high heri- tability (Gregory, 1964). Fertility and livability are examples of low heritability traits. Crossbreeding Practices Fifteen-month-old heifers should be bred to calve at 2 years. Ohio studies indicate that birth weights of Angus and Angus- Hereford crossbred calves are lighter than those of purebred Herefords, and the gestation period of the Angus breed is approximately 10 days shorter than that of the Hereford; the gestation period for crossbred calves is between these two. Other studies show that livability of cross- bred animals is higher than for straight- breds — thus it is often desirable to mate 15-month-old heifers to Angus bulls. Simple crossbreeding. To illustrate this breeding method, we will use a herd of 200 Hereford cows. We will breed 100 top producers to high-grade, fast-gaining bulls of the same breed. We will select heifer replacements for the 200-cow herd from these matings, and we will mate the other 100 Hereford cows in this herd to Shorthorn or Angus bulls. The resulting steer calves from this last mating will be sold for slaughter. Heifers may be sold for replacement purposes, since there ap- pears to be a demand for these crossbreds as range cows. Some commercial cattlemen prefer to buy crossbred heifers as replacement stock rather than produce them. This eliminates managment expenses, but does not provide for herd improvement by scientific selection. Furthermore, other bidders may sometimes price such heifers above market value. CRISSCROSSING AND ROTATIONAL CROSSING These plans should produce the best results. The plans are: (1) two breeds — criss- crossing; (2) three breds — rotational crossing. Two-breed Cross (crisscrossing) Mate all Hereford cows to Shorthorn bulls for three calf crops and replace one-third of the old cows with crossbred yearling heifers each year. Identify each cow and divide into two herds at breeding time. Herd I Herd 11 Cows: Shorthorn-Hereford Cows: Shorthorn-Hereford breed only to Shorthorn bulls breed only to Hereford bulls Heifer replacements Heifer replacements Heifers sired by Shorthorn bulls are used for replacements in Herd II. Heifers sired by Hereford bulls are used for replacements in Herd I. Herd I cows after several generations will Herd II cows after several generations will standardize at % Hereford and % Short- standardize at % Shorthorn and % Here- horn, ford. 16 Three-breed Cross (rotational crossing) Mate all Hereford cows to Angus bulls for three calf crops and replace one-third of the old cows with crossbred yearling heifers each year. Herd I Herd II Herd III Cows: Angus-Hereford Cows: Angus-Hereford Cows: Angus-Hereford breed only to Angus bulls breed only to Hereford breed only to Shorthorn | \ bulfcsy ' \ bulls / Heifer replacements ' ^ Heifer replacements Heifer replacements Heifers sired bv Angus bulls go into Herd II. Heifers sired by Hereford bulls go into Herd III and heifers sired by Shorthorn bulls are used for replacements in Herd I. Cow herds will standardize in breeding as follows: Herd I Cows Yi Shorthorn 2 /i Hereford Vi Angus Herd II Cows Vi Angus -/i Shorthorn Yi Hereford Herd III Cows Yi Hereford 2 /i Angus Yi Shorthorn When using these two breeding pro- grams and natural service, cows from the two herds must be grazed separately dur- ing the breeding season. They can be nan together the rest of the year. Each animal must be properly identified. If artificial insemination is used, cows need not be so separated. The above breeding programs are onlv examples. Other available and adapted breeds can be used in the same manner. The crisscross or rotational crossing has the advantage of continuously maintain- ing hybrid vigor in 100 per cent of the cow herd. This method allows a minimum number of herds to be kept, so that the breeding does not become complicated. These systems also are easily adaptable to artificial insemination. Hvbrid vigor will be maintained as long as these systems are followed and superior bulls are used. Data reported by researchers at the Florida Experiment Station indicate that crisscrossing should maintain high levels of hybrid vigor (Reynolds, et ah, 1963; Meade, 1961). Indiscriminate crossbreeding will be disappointing — satisfactory production cannot be expected unless superior pure- bred sires of the proper breed are used. When no definite plan is followed, there will be a great variation in breed makeup ADVANTAGES OF CROSSBREEDING- Higher conception rate Higher percentage of calf crop Heavier calves at weaning Earlier sexual maturity Fewer calving problems Higher milk production Greater longevity Greater insect and/or climatic adaptability Fewer services per conception Earlier conception in the breeding -DISADVANTAGES OF CROSSBREEDING Loss of uniformity in color — esthetic value (in some crosses this can be avoided — Red Angus, Red Short- horn, and Hereford) Expense of maintaining and manag- ing at least two herds Usually not practical under unfenced range conditions 17 of individual cows. This leads to variation lish premium prices on carefully selected in quality and production of individual high-producing purebred bulls. Thus, animals. rather than decreasing the important role Regardless of the quality of his cows of the purebred breeder, this practice will the cattleman can make progress through accentuate the ever present need for high- crossbreeding if he uses superior bulls and performance sires. In this respect official follows a systematic and scientific pro- performance records become ever more gram. Crossbreeding will tend to estab- important. LITERATURE CITED Bell, F. L. 1966. Sexton-Eidman beef improvement program. Mimeo, 8 pp. Bellows, R. A., T. M. Riley, N. M. Kieffer, J. J. Urick, J. S. Brinks, and R. T. Clark 1964. Preliminary studies of sperm production and breeding ability in young straight and crossbred bulls. J. Animal Sci. abstract 23(2): 593-94. Black, W. H., A. T. Semple, and J. L. Lush 1934. Beef production and quality as influenced by crossing Brahman with Here- ford and Shorthorn cattle. U.S. Dept. Agr. Tech. Bui. 417. 53 pp., illus. Carpenter, G. A. 1965. Trends in production and consumption and market possibilities for beef in western Europe. Pp. 15-23. Carroll, F. D. 1966. Inspection of Angus, Hereford and Shorthorn cows, with crossbred calves at side. Proc. Animal Husb. Beef Cattle Day, UC Davis, April 16. Pp. 34-35. Deakin, Alan and G. W. Muir 1935. Hybridization of domestic cattle, bison and yak. Canada Dept. Agr. Pub. 479, Tech. Bui. 2. 31 pp., illus. Flower, A. E., J. S. Brinks, J. J. Ruick, and F. S. Willson 1963. Comparisons of inbred lines and linecrosses for performance traits in Here- ford range cattle. J. Animal Sci. 22(4):914-18. Fuller, J. G. 1928. Crossbreeding types for baby beef production. Amer. Soc. Animal Prod. Proc. 1927:53-57. Gaines, J. A., W. H. McClure, D. W. Vogt, R. C. Carter, and C. M. Kincaid 1966. Heterosis from crosses among British breeds of beef cattle: fertility and calf performance to weaning. J. Animal Sci. 25(1):5-13. Gregory, K. E., L. A. Swiger, R. M. Koch, L. J. Sumption, W. W. Rowden, and J. E. 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Animal Sci. 21(4):875-79. 1964. Lamb weights in some pure breeds and crosses. J. Animal Sci. 23(1): 105-10. Stonaker, H. H. 1963. A genetic hypothesis for sex-mating system interactions in growth of cattle and poultry. J. Animal Sci. 22:320. Wentworth, E. N. 1912. Concerning "blue-gray" cattle. American Breeder 5:9-10. Winters, L. M., O. M. Kiser, P. S. Jordan, and W. H. Peters 1935. A six-year study of crossbreeding swine. Minn. Agr. Exp. Sta. Bull. 320. 18 pp., illus. Woodward, R. R. 1960. A preliminary look at Charolais. Personal communication. 19 Acknowledgments The authors are indebted to Drs. G. E. Bradford, F. D. Carroll, and W. C. Rollins, Animal Husbandry Department, Davis, for advice and assistance in the preparation of this manuscript. Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. D.stnbutcd in furtherance of the Acts of Congress of May 8, and June 30, 1914. George B. Alcorn, Director, California Agricultural Extension Service 15w-l,'67(G8185)VL