UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION CIRCULAR No. 254 November, 1922 THE USE OF ARTIFICIAL LIGHT TO INCREASE WINTER EGG PRODUCTION By J. E. DOUGHERTY Purpose. — The use of artificial lighting of poultry houses to in- crease winter egg production is of American origin. It was first used on the assumption that fowls do not require more hours of rest in winter than in summer and that if artificial lighting were used in winter to produce similar conditions of daylight and darkness as exist in spring and summer, increased production ought to result. In winter the hours of daylight are short as compared with the hours of darkness, whereas during the spring and summer seasons the reverse is true. For example, at the University Farm, Davis, the average time of daybreak during the short winter months is 7 a.m. and the average time when fowls go to roost at night is 5 p.m. During the winter, therefore, laying fowls must spend approximately 14 hours on the roost. Only 10 daylight hours are then left to them in which to exercise and consume sufficient feed to (1) take care of their body needs during the long night period and (2) supply food materials for the manufacture of eggs. The capacity of a hen's crop being limited, she cannot, during the winter months, fill her crop before going to roost with much more than enough food to nourish her body during the long hours of darkness. Very little is left to be manufactured into eggs. The result is that egg production in the winter is greatly reduced as compared with other seasons of the year. Extended experiments and field observations have demonstrated that artificial lighting will stimulate egg production provided the flock is intelligently fed. By increasing the lighted hours to compare with spring and summer conditions, the fowls are given more time to exercise and eat and less time is spent on the roosts. Value of Artificial Lighting. — Investigations conducted at this and other stations have shown that winter production can be in- creased to as high as 50 or 60 per cent by artificial lighting. The hens begin to respond to such lighting within a week or ten days and 2 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION the full effect is obtained in about three weeks. A maximum produc- tion can then be expected to continue into early March. At that time there is likely to occur a slump in egg yield, which may be accom- panied by a more or less severe molt lasting from two weeks to more than a month. Artificial lighting appears to increase winter production at the expense of spring production but the annual production of the flock is not necessarily increased. The principal value of this practice is that it induces an increased production in winter when eggs are high in price, hence without any increase in annual production, arti- ficial lighting will result in a greater money return. Effect on Pullets and Hens. — It has been assumed that (1) a lay- ing hen does not need any more sleep and rest in winter than in summer to keep in good health and (2) the only reason for her spend- ing a longer time on the roosts in winter is because there are more hours of darkness. Experiments and practical experience seem to prove quite conclusively the soundness of these assumptions because the use of artificial lighting for fourteen hours a day has not been found in any way injurious to a hen's health and vigor. It simply exerts a stimulus on production by lengthening the working day so that the hen can eat and exercise more. It does not over stimulate or force in the sense that a drug does. It is, therefore, not injurious to either pullets or hens and there should be no ill effects carried over from year to year. Effect on Breeding Hens. — Investigations conducted at this station indicate that it is inadvisable to use artificial lighting with breeding fowls. The consensus of opinion among breeders and investigators is that it is desirable to use artificial light only with pullets and hens pro- ducing eggs for market and not with breeding flocks. It is held that if the breeding fowls are allowed to build up their strength through the winter period in preparation for a large yield of hatching eggs in spring, much better hatches and stronger chicks will be obtained because their vitality has not been reduced by a rather long period of heavy production preceding the hatching season. But if lights are used with the breeding hens, they should not be started until after the birds have entirely finished the molt and should not be turned on before 5 a.m. daily, i.e., lighting should be used in greater moderation than with flocks producing market eggs. In hatching tests made of eggs set between December 20 and March 20, breeding flocks that were given artificial light from 5 a.m. to daylight each morning beginning December 1, gave 87 per cent fertil- ity and 52 per cent of all the eggs set hatched, whereas flocks that Circular 254] TH e USE OF ARTIFICIAL LIGHT 3 were given no artificial light gave 96 per cent fertility and 61 per cent of all eggs set .hatched. Source of Light. — Gasoline lanterns, acetylene lights, coal oil lanterns or lamps, and electric lights represent the different sources of light which have been used in poultry houses. Coal oil lanterns have not proved satisfactory as they give too little illumination. Gaso- line lanterns, are unsafe because the air intake holes in the burners are readily choked with the dust stirred up by the fowls scratching. Electric lights have been found most convenient and are the least dangerous from the standpoint of fire hazard. Amount of Light. — Poultry houses should be supplied with suf- ficient illumination to amply light the mash hoppers and scratching floor so that the fowls can readily see to scratch the grain out of the litter and eat from the hoppers. The use of reflectors will prove of great value in concentrating the light on the floor where it is needed. Metal reflectors, enameled green outside and white inside, are very satisfactory for this purpose and are inexpensive and durable. A wide, flat shade from 12 to 14 inches in diameter will usually dis- tribute the light more effectively than a narrow and more conical one. One twenty-five watt lamp, equipped with a metal shade should be sufficient for sixty square feet of floor space. The size and interior arrangement of the house will determine the location of the lights to obtain the most effective illumination. They can be most conveniently hung six and one-half feet above the floor where they are out of the way and least liable to be broken. j In houses which are lighted by electricity and which have wide droppings boards that partially shade the floor beneath, one or more lights can be fastened to the under side of the droppings boards to better illuminate this part of the scratch floor. When to Use Lights. — The use of artificial lighting in California may begin as early as October first and should be discontinued in the spring when day breaks sufficiently early to render lights of no further value in stimulating production. In trials it has been found that the natural stimulus on production due to the opening of the breeding season and the lengthened period of daylight makes artificial light of practically no value after March first. Data compiled from sunrise and sunset tabulations supplied by the San Francisco office of the United States Weather Bureau for meridian one hundred and twenty, show the average hour of sunrise between October 1 and March 1 to be 6 :59 a.m., and the average hour of sunset to be 5 :18 p.m. The difference between 6 :59 a. m. when the sun rises, and 5:18 p.m., when it sets, is ten hours and 19 minutes. To give a laying flock a fourteen hour day, artificial light would 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION have to be used for three hours and 41 minutes. Whether or not this artificially lengthened part of the day can be most beneficially given in the morning, at night, or both in the morning and at night, has not been definitely determined. Trials indicate that morning lighting is as effective as night lighting or a combination of both morning and night lighting. It has the advantage of doing away with the necessity of dimming the lights which is done about ten minutes before the close of the daily lighted period to imitate the approach of darkness and get the birds on the roosts. If a fourteen hour day, using morning lights only, were the sys- tem decided on, the addition of three hours and forty-one minutes to the daylight period would require that the lights be turned on at 3:18 a.m. Repeated trials, however, have not shown that there is any advantage to be gained in using lights before 4 :00 or 4 :30 a.m. When beginning the use of artificial lighting in the fall, the lamps should be lighted fifteen minutes before daylight for the first three days and then the time advanced by five or ten minute periods daily until the hour is reached at which they are to be regularly used. In spring the lights should be gradually discontinued in the same way, beginning the latter part of February. Installing Electric Lights. — If electric lighting is to be used only in the morning, the wiring should be done in the usual way, but if night lighting is used, provision will have to be made to dim the lights just before they are turned off each night in order to get the birds upon the roosts. Two simple systems of dimming can be used and an electrician can advise how to install either system. The first system consists in running three wires through the build- ing about six inches apart. The bright lights (25 Watt) are then connected to the center wire and one outside wire and the dim lights (10 Watt) are connected to the center wire and the other outside wire. If more than one bright light is used in each pen, half as many dim lights may be sufficient. A switch is then cut into each of the two outside wires between the lights and the fuse block. By opening one switch and closing the other, either set of lights will burn depending on which switch is opened or closed. The second method is to cut in a resistance coil around a secondary switch which should be located between the lights and the main switch. With the main switch closed, closing the secondary switch will cause the lights to burn brightly; opening the secondary switch will force the electricity through the resistance coil and dim the lights. The strength of the resistance will govern the amount the lights are dimmed. Only two wires are used with this method. Circular 254] THE USE OF ARTIFICIAL LIGHT 6 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Time Switches. — Electrically operated time switches can be pur- chased which will automatically turn the lights on and off at set times, and dim these lights in any way desired, depending on the construction of the switch. Such devices are quite costly, however, and for morning lighting, a home-made time switch such as is described below will prove just as satisfactory. For night lighting the switches can be readily operated by hand. The time switch illustrated in Fig. 1 consists of a small wooden box with a tight cover to keep out dust, an inexpensive alarm clock having a one-piece alarm key which turns when the alarm goes off, a small, single blade knife switch, a 4" piece of hack saw blade, a small spool, and a short piece of coil spring cut from a % 6 "xl6" Perfection door spring. The method of construction should be clear from the drawing. This switch will turn the lights on but will not turn them off. When morning lights are used, the turning off of the lights shortly after daybreak is entirely a matter of economy as they are then no longer of any value. Feeding. — Since the effectiveness of artificial lighting is due pri- marily to feeding and exercise, best results can not be expected unless the poultry keeper takes the opportunity afforded by the use of lights to feed his hens to the best advantage. Extending the working day, without keeping the hens busy scratching and eating so as to send them to bed with full crops, cannot be expected to bring results. Bringing them off the roosts at 4 :30 a.m. without having grain in the litter for them to scratch out, will not prove of much value. They must be kept busy and they must be well and skillfully fed. Some poultry keepers using morning lights, scatter the morning feed of grain in the litter at night after the fowls have gone to roost. Others feed the birds when the lights go on in the morning. When evening lights are used, the night feeding of grain is fed later. A light noon feeding of a moist, crumbly mash, made from the regular dry mash mixture, will also be found to greatly aid in in- creasing winter production. This mash may be beneficially moistened with milk, and finely-cut roots or tender green feed should be added to it as often as possible. Since fowls must be confined a great deal in winter and the weather is then more unfavorable than at other seasons, they will respond much better to special care and feeding than in spring and summer when more favorable weather prevails. The high prices obtained for eggs in winter should well repay the poultry keeper for any extra care that -will increase the production of his flock. 1 *For detailed information on the subject of poultry feeding, the reader is referred to Circular No. 242 of the California Agricultural Experiment Station. STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION BULLETINS No. 253. Irrigation and Soil Conditions in the Sierra Nevada Foothills, California. 261. Melaxuma of the Walnut, "Juglans regia." 262. Citrus Diseases of Florida and Cuba Compared with Those of California. 263. Size Grades for Ripe Olives. 267. Experiments with Stocks for Citrus. 268. Growing and Grafting Olive Seedlings. 270. A Comparison of Annual Cropping, Bi- ennial Cropping, and Green Manures on the Yield of Wheat. 273. Preliminary Report on Kearney Vine- yard Experimental Drain. 275. The Cultivation of Belladonna in Cali- fornia. 276. The Pomegranate. 278. Grain Sorghums. 279. Irrigation of Rice in California. 280. Irrigation of Alfalfa in the Sacramento Valley. 283. The Olive Insects of California. 285. The Milk Goat in California. 286. Commercial Fertilizers. 287. Vinegar from Waste Fruits. 294. Bean Culture in California. 297. The Almond in California. 298. Seedless Raisin Grapes. 299. The Use of Lumber on California Farms. 304. A Study on the Effects of Freezes on Citrus in California. 308. I. Fumigation with Liquid Hydrocyanic Acid. II. Physical and Chemical Prop- erties of Liquid Hydrocyanic Acid. 309. I. The Carob in California. II. Nutri- tive Value of the Carob Bean. 310. Plum Pollination. 312. Mariout Barley. No. 313. 316. 317. 320. 321. 323. 324. 325. 330. 331. 332. 334. 335. 336. 337. 339. 340. 341. 342. 343. 344. 345. 346. 347. 348. Pruning Young Deciduous Fruit Trees. The Kaki or Oriental Persimmon. Selections of Stocks in Citrus Propa- gation. Control of the Coyote in California. Commercial Production of Grape Syrup. Heavy vs. Light Grain Feeding for Dairy Cows. Storage of Perishable Fruit at Freezing Temperatures. Rice Irrigation Measurements and Ex- periments in Sacramento Valley, 1914-1919. Dehydration of Fruits. Phylloxera-Resistant Stocks. Walnut Culture in California. Preliminary Volume Tables for Second- Growth Redwoods. Cocoanut Meal as a Feed for Dairy Cows and Other Livestock. The Preparation of Nicotine Dust as an Insecticide. Some Factors of Dehydrater Efficiency. The Relative Cost of Making Logs from Small and Large Timber. Control of the Pocket Gopher in Cali- fornia. Studies on Irrigation of Citrus Groves. Hog Feeding Experiments. Cheese Pests and Their Control. Cold Storage as an Aid to the Market- ing: of Plnms. Fertilizer Experiments with Citrus Trees. Almond Pollination. The Control of Red Spiders in Decidu- ous Orchards. Pruning Young Olive Trees. CIRCULARS No. 70. Observations on the Status of Corn Growing in California. 82. The Common Ground Squirrels of Cali- fornia. 87. Alfalfa. 110. Green Manuring in California. 111. The Use of Lime and Gypsum on Cali- fornia Soils. 113. Correspondence Courses in Agriculture. 115. Grafting Vinifera Vineyards. 126. Spraying for the Grape Leaf Hopper. 127. House Fumigation. 129. The Control of Citrus Insects. 138. The Silo in California Agriculture. 144. Oidium or Powdery Mildew of the Vine. 148. "Lungworms." 151. Feeding and Management of Hogs. 152. Some Observations on the Bulk Hand- ling of Grain in California. 155. Bovine Tuberculosis. 157. Control of the Pear Scab. 159. Agriculture in the Imperial Valley. 161. Potatoes in California. 164. Small Fruit Culture in California. 165. Fundamentals of Sugar Beet Culture under California Conditions. 166. The County Farm Bureau. 167. Feeding Stuffs of Minor Importance. 169. The 1918 Grain Crop. 170. Fertilizing California Soils for the 1918 Crop. 172. Wheat Culture. 173. The Construction of the Wood-Hoop Silo. No. 174. Farm Drainage Methods. 175. Progress Report on the Marketing and Distribution of Milk. 178. The Packing of Apples in California. 179. Factors of Importance in Producing Milk of Low Bacterial Count. 181. Control of the California Ground Squirrel. 182. Extending the Area of Irrigated Wheat in California for 1918. 183. Infectious Abortion in Cows. 184. A Flock of Sheep on the Farm. 188. Lambing Sheds. 189. Winter Forage Crops. 190. Agriculture Clubs in California. 193. A Study of Farm Labor in California. 198. Syrup from Sweet Sorghum. 201. Helpful Hints to Hog Raisers. 202. County Organizations for Rural Fire Control. 203. Peat as a Manure Substitute. 205. Blackleg. 206. Jack Cheese. 208. Summary of the Annual Reports of the Farm Advisors of California. 209. The Function of the Farm Bureau. 210. Suggestions to the Settler in California. 212. Salvaging Rain-Damaged Prunes. 214. Seed Treatment for the Prevention of Cereal Smuts. 215. Feeding Dairy Cows in California. 217. Methods for Marketing Vegetables in California. CIRCULARS — Continued No. 218. Advanced Registry Testing of Dairy Cows. 219. The Present Status of Alkali. 223. The Pear Thrips. 224. Control of the Brown Apricot Scale and the Italian Pear Scale on Decid- uous Fruit Trees. 225. Propagation of Vines. 227. Plant Diseases and Pest Control. 228. Vineyard Irrigation in Arid Climates. 230. Testing Milk, Cream, and Skim Milk for Butterfat. 231. The Home Vineyard. 232. Harvesting and Handling California Cherries for Eastern Shipment. 233. Artificial Incubation. 234. Winter Injury to Young Walnut Trees during 1921-22. 235. Soil Analysis and Soil and Plant liter- relations. 236. The Common Hawks and Owls of Cali- fornia from the Standpoint of the Rancher. No. 237. 238. 239. 240. 241. 242. 243. 244. 245. 246. 247. 248. 249. 252. 253. Directions for the Tanning and Dress- ing of Furs. The Apricot in California. Harvesting and Handling Apricots and Plums for Eastern Shipment. Harvesting and Handling Pears for Eastern Shipment. Harvesting and Handling Peaches for Eastern Shipment. Poultry Feeding. Marmalade Juice and Jelly Juice from Citrus Fruits. Central Wire Bracing for Fruit Trees. Vine Pruning Systems. Desirable Qualities of California Bar- ley for Export. Colonization and Rural Development. Some Common Errors in Vine Pruning and Their Remedies. Replacing Missing Vines. Supports for Vines. Vineyard Plans.