Artificial Light for Activating Males and Females to Higher Fertility*

ARTIFICIAL LIGHT AND FERTILITY 321 date, and a formula for such a correction is developed. ACKNOWLEDGEMENTS The author wishes to express his appreciation to Miss H. N. Turner, Section of Mathematical Statistics, C.S.I.R.O., and to his colleague, Mr. J. A. Morris, for valuable criticism and suggestions. REFERENCES Byerly, T. C, and C. W. Knox, 1946. Date of hatch and day length affect age at first egg. Poultry Sci. 25:587-592. Dickerson, C. W., and L. N. Hazel, 1944. Effectiveness of selection on progeny performance. A supplement to earlier culling in livestock. J. Agr. Res. 69: 459-476. Godfrey, A. B., 1946. Value of sisters' performance in selecting breeding cockerels. Poultry Sci. 25: 148-156. Lemer, I. M., and L. W. Taylor, 1939. A statistical study of winter pause on White Leghorn. J. Agr. Res. 59: 199-210. Lerner, I. M., and L. W. Taylor, 1944. Early recognition of superior families. Poultry Sci. 23: 413 417. Lerner, I. M., and D. M. Cruden, 1948. The heritability of accumulative monthly and annual egg production. Poultry Sci. 27: 67-78. Skaller, F., 1954. Studies on the measurement of egg production in poultry breeding work. 1. The optimal period for measuring first year's egg production. Poultry Sci. 33: 29-35. Artificial Light for Activating Males and Females to Higher Fertility* ' I V HE fertility problem in domestic *- chickens and turkeys is of considerable economic importance because in breeding operations infertile eggs represent a significant loss. In the highly competitive field of poultry breeding, it is important that every loss be reduced to a minimum. Many workers have made valuable contributions to our knowledge of what may be done to improve fertility, but investigators are not in complete agreement. It seems desirable, therefore, to study an important phase of the problem in a closed flock of Rhode Island Reds bred for high fecundity for many years. STUDIES CONCERNED WITH FERTILITY A physiological character like fertility offers many ramifications, and valuable * Contribution No. 905 from the Massachusetts Agricultural Experiment Station. F. A. HAYS Massachusetts Agricultural Experiment Station, Amherst (Received for publication July 16, 1953) data have been presented by a number of investigators. A brief review of some pertinent information leading to this investigation may be of value. Duration of fertility from single controlled matings has received considerable attention. Crew (1926) pointed out that fertile eggs may be expected in 24 to 48 hours after the introduction of the male. He found the life span of the sperm in the female body had a range of 15 to 20 days and occasionally longer. Eggs laid after the first week following the removal of the male commonly failed to hatch. If a second male is brought in, he will fertilize most of the eggs from the seventh to the tenth day on. Curtis and Lambert (1929) reported that the onset of fertility ranged from 24 hours to 7 days with a mean of 57.1 hours. The average number of fertile eggs from a single mating was 5.6, and the maximum was 11. Slight

322 F. A. HAYS evidence of selective fertilization was found. Differences in fertility were noted in groups of pullets or hens mated to either cocks or cockerels. Nicolaides (1934) recorded a range of 19 to 238 hours with a mean of 66.24 hours between time of mating and the appearance of fertile eggs. From 1 to 14 eggs were fertilized by a single mating, and more intense layers were more fertile. The average duration of fertility was 14.83 days, and the maximum was 29 days. One mating every four days seemed satisfactory, and pen and stud matings were equally effective. Age of breeding stock is known to affect fertility. Hays and Sanborn (1939) showed that fertility in both males and females declines with age, but that the rate of decline in males was greater than in females. Insko, Steele and Wightman (1947) reported a decline in fertility as age of females increased in White Leghorns and Rhode Island Reds. Males show a pronounced seasonal effect on both volume and density of semen according to the work of Parker, McKenzie and Kempster (1942). The effect of different amounts of artificial light has been extensively studied by Lamoreaux (1943). He observed that the intensity of light was not important because 10 to 1,000 watt bulbs, when used for 14 hours daily over a 2\ month period with cockerels, produced no significant differences in yield of semen. The maximum response in males resulted from exposure for 12 hours or more daily for one month. The duration of response ranged from less than 4 months to more than 9 months, and was influenced by other factors than light. Fertility in females may or may not be influenced by rate of laying. Knox (1927) observed no relation between rate of laying and fertility. Lamoreaux (1940), on the other hand, reported that hens that laid 13 to 22 eggs in six weeks produced a larger proportion of infertile eggs than those that laid at a higher rate. Hens that laid in clutches of more than three had a significantly higher fertility than those laying in smaller clutches. Wilson (1948) was unable to support Lamoreaux's findings. Temperature and length of day may affect fertility. Hays and Sanborn (1939) presented data showing a linear increase in fertility in mating pens as the outside temperature increased from 16 to 46 in the spring season. Birds appeared to be less active when the outside temperature was below freezing. Lamoreaux (1942) found no relationship between outside temperatures ranging from 23 to 50 in a six-year period. Parker, McKenzie and Kempster (1942) showed an important relationship between length of day and semen production during the winter and spring season. Effects of stale sperm have been given considerable attention in recent years. Parker, McKenzie and Kempster (1942) found no evidence that the length of time that sperm had been in the oviduct following artificial insemination affects hatchability of fertile eggs. Nalbandov and Card (1943) presented very good evidence that eggs fertilized by sperm that had been in the oviduct for longer than 10 days hatched poorly because of high embryonic mortality during the first 5 days of incubation. No unusual embryonic mortality occurred in eggs laid from 1 to 10 days after the removal of males. Fertility declined rapidly 10 days after the males were removed. Blyth (1945) concluded that infertility and embryonic mortality behave as inherent individual characteristics and exhibit similar basic seasonal trends which tend to obscure the fundamental relationship. Viability and fertility may be associ-

ARTIFICIAL LIGHT AND FERTILITY 323 ated. Data over a 10-year period presented by Hays (1948c) suggest that females whose sisters were lower than average in viability are likely to be more fertile than females from the more viable families. Hays (1950a) reported that females with high fertility did not transmit low viability to their daughters. Bernier, Taylor and Gunns (1951) found that inbred hens were definitely less fertile than outbred hens irrespective of the kind of male to which they were mated. Rather recent evidence indicates that fertility has an inherited basis. In inbred chickens, Wilson (1948) estimated that the degree of heritability of fertility, without adjusting for inbreeding, was 10 percent, which is a low degree of heritability. Gowe and Hutt (1949) expressed the view that fertility in the different lines tested was of genetic origin. Reciprocal crosses between highly infertile and highly fertile birds indicated that the females were responsible to a greater extent than the males. Hays (1950b) pointed out over a ten-year period that high fertility is transmitted from sire to daughter, and that dams selected for high fertility do not transmit this character to their daughter. The data showed that breeding males may be effectively selected for high fertility either on their mates' records or on their daughters' records. Studies on fertility in turkeys (Blow et al., 1951) demonstrated a heritability of about.30. This is a moderately high degree of heritability. Burrows and Titus (1939) were among the first to call attention to the higher seasonal variability in volume of semen and in sperm content from cockerels and cocks. Crew (1925) fed dessicated thyroid in small amounts daily to four very old cocks and seven very old hens. The hens showed increased egg production and the males were activated to fertilize the eggs. Koch (1936) has given some evidence that old males may be activated to satisfactory fertility in cold weather by injecting male testicular hormones. Shoffner and Smyth (1944) successfully activated poorly developed cockerels by injections of pregnant mare serum. In a preliminary trial, Hays (1945) obtained some evidence that injections of pregnant mare serum into males were slightly more effective than limited artificial light to improve fertility in winter and early spring. In a second trial, Hays (1948a) showed that heavier injections of pregnant mare serum do improve the fertility of yearling males to a slightly greater extent than does limited artificial light. Limited doses of thyroxine and artificial light were also compared by Hays (1948b). In this test, artificial light was slightly more effective than thyroxine in preventing a seasonal decline in fertility. Many studies have shown that artificial light will stimulate winter egg production, but it seems unnecessary to review the findings in this field. From 1949 to 1953, it was decided to explore the value of artificial light in affecting fertility during the hatching season in March and April. These data will be presented in this report. METHODS OF EXPERIMENTATION All-night lights were tested in several ways to discover possible effects on fertility in males and females of various ages in different combinations. The intensity of light was about 3 footcandles on the floors of the pens. All birds used were Rhode Islands Reds bred for high fecundity. As a rule, from eight to ten females were placed in each pedigree breeding pen. Hatching eggs were saved for a six-week period beginning early in February and ending in the latter part of March. All

324 F. A. HAYS eggs were held at a cellar temperature about 60 for one week and incubated so as to produce four hatches in March and two in April. All eggs were candled on the sixteenth day, and infertile eggs were removed from the incubator. Fertility records were based on individual females and male fertility records. The fertility records of the males were averages of his mates. Control pens consisted of the same number of pens as were treated, and the birds were of comparable ages. Morning lights using 3 footcandles were turned on at 4:00 a.m. and continued to 8:00 a.m. each day. The number of pens made up of comparable birds was the same as in the other two groups. SECTION 1 Ail-Night Lights for Thirty days. Allnight lights were used for 30 days from January 1 to February 8,1949. This treatment was given to four pens which may be compared in fertility with the four control pens. Unfortunately, one male had to be removed from the treated pens and one male from the controls. By studying the data obtained, the fertility of one yearling and two 2-year-old males under all-night lights may be compared with three yearling males receiving no artificial light as controls. Pullet breeders were placed in all pens. In Table 1 the mean fertility records of the six hatches are set down. TABLE 1. Mean fertility records using all-night lights for thirty days and controls, 1949 Lighted 64.9 85.6 71.2 74.3 85.8 88.9 Controls 76.5 87.5 89.2 79.6 82.8 83.8 In Table 1 the lighted pens may be compared in fertility with controls receiving only natural light. Effects may be measured by the rate of increase in fertility through the hatching season. Means were first fitted to a straight line by the method of least squares, and the standard error of the slope was then calculated by the method of Van Uven (1935). The slope of the line representing the lighted group was 3.53 + 1.72 indicating a significant increase in fertility through the hatching season. In the control group, the slope was.37+1.15 indicating no seasonal change. Interpretation of these data indicates that all-night lights for 30 days did produce a significant increase in fertility. Morning Lights for Sixty Says. Natural daylight was supplemented by morning lights turned on at 4:00 a.m. In this group, two 24-month-old males were mated to 12 pullets. Also two yearling males were mated to 22 hens ranging in age from 36 to 60 months. The data are given in Table 2. TABLE 2. Mean fertility records using morning lights for 60 days and controls, 1949 1 2 3 4 5 6 Morning Lights 24-month-old males and pullets 90.0 93.4 88.4 94.180.0 95.4 24-month-old males and old hens 96.0 92.8 92.0 94.4 89.4 94.5 Controls 24-month-old males and pullets 76.5 87.5 89.2 79.6 82.8 83.8 The data in Table 2 indicate no significant changes in the fertility in the two treated groups as the hatching season advanced. In fact, fertility was unusually high both from the pullets and from the very old hens. As compared with the controls, the group receiving morning lights were definitely superior, suggesting that artificial light in the morning had a stimulating effect on pullets and very old hens when mated to 24-month-old males.

ARTIFICIAL LIGHT AND FERTILITY 325 In general, data obtained on the first year of the test indicate that morning lights given over a 60-day period may induce higher fertility than all-night lights given for 30 days, but the rate of increase in fertility was significant under all-night lights and insignificant under morning lights. Either type of light treatment has given higher fertility than that given with natural light. SECTION 2 Section 2 includes observation on allnight lights given for 60 days and morning lights for the same period as well as controls receiving no artificial light during the 1950, 1951, and 1952 breeding seasons. All-night lights were given to 4 cockerels mated to 27 very old hens, and 7 old males were mated to 55 pullets. Controls consisted of 7 old males mated to 56 pullets. TABLE 3. All-night lights for 60 days and controls, 1951 and 1952 1 2 3 4 5 6 All-night Lights Cockerels mated to old hens 85.3 86.0 84.2 88.5 94.2 84.9 24 months old 36 months old 48 months old Cocks mated to pullets 84.0 77.0 73.9 73.6 78.0 71.0 Controls 24 months old and 36 months old Cocks mated to pullets 81.4 82.6 81.3 88.3 78.3 75.2 Table 3 indicates that cockerels mated to very old hens gave no significant increase in fertility during the hatching season. Fertility in these matings was generally satisfactory, and cockerels were not stimulated by all-night lights. In a two-year period, old males mated to pullets showed a significant decline when exposed to all-night lights for 60 days, whereas in Section 1 all-night lights for 30 days significantly increased fertility in similar matings. There is a possibility that light treatment for 60 days may produce unfavorable effects on old males. Control matings of old males on pullets for a two-year period failed to show a significant decline in fertility during the hatching season. Morning Lights and Controls, 1950-1952. Four cockerels were mated to 29 very old hens, and 7 old cocks were mated to 55 old hens. Morning lights were given for 60 days along with natural daylight. Controls consisted of 7 old males mated to 56 pullets as indicated in Table 4. TABLE 4. Morning lights and controls, 1950-1952 Morning Lights Cockerels mated to old hens 91.6 88.8 87.3 83.1 79.1 84.0 Old males mated to old hens 83.1 85.5 79.5 81.9 79.9 78.0 Controls Old males mated to pullets 81.4 82.6 81.3 88.3 78.3 75.2 When exposed to morning lights, cockerels mated to old hens had a significant decline in fertility during the hatching season which the controls did not show. Old males mated to old hens gave no significant decline during the hatching season. Speaking generally, there is little evidence in Table 4 that morning lights will improve fertility over natural light. SECTION 3 The last observations were made in the Spring of 1953. In this test, three males that were to be exposed to allnight lights and three that were to receive morning lights were given a preliminary light exposure for three weeks starting December 19, and the breeding pens were made up on January 9. In this test, 3 pens were included in each of the three groups: all-night lights, morning lights, and controls. After the breeding pens were assembled, light exposure was continued for 60 days.

326 F. A. HAYS All-night Lights for 80 Days and Controls, 1953. Two yearling males and one 2-year-old male were mated to 11 yearlings and eight 2-year-old hens. Males were subjected to all-night lights for 80 days, and females for 60 days. Controls included 1 yearling and 1 two-year-old male mated to 11 yearlings and four 2-year-old hens all exposed to natural light. TABLE 5. All-night lights for 80 days for males and 60 days for females and controls, 1953 All-night Lights 65.6 63.2 57.4 48.7 43.8 48.8 Controls 94.8 91.2 85.1 86.0 90.5 86.4 Table 5 indicates that long exposure of males to all-night lights resulted in decline in fertility through the breeding season. This decline was not statistically significant, however. Control birds exhibited no significant change in fertility in the hatching season. A comparison of treated with controls brings out a rather marked superiority in the fertility of the controls. Here again is evidence that allnight lights for longer than 30 days may depress fertility in old birds. Males Subjected to Morning Lights for 80 Days and Females for 60 Days and Controls. Three cocks were exposed to morning lights for three weeks before mating. Mating pens were made up on January 9 and consisted of two yearlings and one two-year-old male mated to 12 yearlings and 10 two-year-old hens. Lights were continued through a 60-day period. Results are summarized in Table 6. Table 6 indicates that morning lights given to cocks mated to old hens did increase fertility significantly. The rate of increase was.91+.40. Control birds, however, showed no change in fertility during the hatching period. These results TABLE 6. Morning lights for 80 days and controls, 1953 Morning Lights 88.0 87.4 92.8 92.4 91.0 92.3 Controls 94.8 91.2 85.1 86.0 90.5 86.4 suggest that morning lights over as long a period as 80 days for males and 60 days for females may stimulate cocks and hens to higher fertility. SUMMARY A study was made comparing the effects of different exposures to all-night lights and to morning lights on fertility in Rhode Island Red males and females of various ages. The data collected over a five-year period furnish information on several points. All-night light treatment of birds in the breeding pens for a period of 30 days had a definite stimulating effect on the fertility of cocks when mated to pullets. Morning lights given for 60 days to yearling males mated to pullets had no significant effect on fertility as the season advanced. Cockerels mated to old hens and the birds exposed to all-night lights for sixty days showed no significant effects. Cockerels mated to old hens and the birds exposed to morning lights for 60 days gave no response in fertility. Old males and old hens when mated and exposed to morning lights gave no reaction. An exposure of old males for 80 days and old hens for 60 days gave a significant lowering of fertility as the breeding season advanced. In the last year of the test, mating between old males and old hens when males were exposed to morning lights for 80 days

COLLEGIATE POULTRY CLUB 327 and females for 60 days, there was a significant increase in fertility as the hatching season advanced. In general, our data indicate that a 30- day exposure to all-night lights gives the best results with old males. There is evidence that longer exposures to all-night lights may reduce fertility. Cockerels are little affected by artificial light, and there is little evidence that females of various ages are affected as far as fertility is concerned. REFERENCES Bernier, P. E., L. W. Taylor and C. A. Gunns, 1951. The relative effects of inbreeding and outbreeding on reproduction in the domestic fowl. Hilgardia, 20:529-628. Blow, W. L., E. W. Glazener, R. S. Dearstyne and C. H. Bostian, 1951. Inheritance of fertility in turkeys. Poultry Sci. 30: 313-314. Blyth, J. S. S., 1945. Infertility and embryonic mortality in the domestic fowl. Proc. Roy. Soc. Edinb. 62: 191-201. Burrows, W. H., and H. W. Titus, 1939. Some observations on semen production of the male fowl. Poultry Sci. 18: 8-10. Crew, F. A. E., 1925. Rejuvination of the aged fowl through thyroid medication. Proc. Roy. Soc. Edinb. 45:252-260. Crew, F. A. E., 1926. On fertility in the domestic fowl. Proc. Roy. Soc. Edinb. 46:230-238. Curtis, V., and W. V. Lambert, 1929. A study of fertility in poultry. Poultry Sci. 8: 142-150. Gowe, R. S., and F. B. Hutt, 1949. Studies of genetic infertility in the fowl. Poultry Sci. 28: 764-765. Hays, F. A., 1945. Male sex hormones and artificial light as activators in the spermatogenesis of adult males. Poultry Sci. 24: 66-71. Hays, F. A., 1948a. Male sex hormones and artificial light as activators in the spermatogenesis of adult males. 2. Poultry Sci. 27: 3-6. Hays, F. A., 1948b. Thyroxine and artificial light as activators in the spermatogenesis of males. Poultry Sci. 27: 84-86. Hays, F. A., 1948c. Viability and fertility in Rhode Island Red females. Poultry Sci. 27: 186-193. Hays, F. A., 1950a. Further studies on viability in Rhode Island Reds. Poultry Sci. 29: 193-194. Hays, F. A., 1950b. Is fertility in domestic fowl regulated by inheritance? Poultry Sci. 29: 171-175. Hays, F. A., and R. Sanborn, 1939. Factors affecting fertility in Rhode Island Reds. Massachusetts Agr. Exp. Sta. Bui. 359. Insko, W. M., Jr., D. G. Steele and E. T. Wightman, 1947. Reproductive phenomena in aging hens. Kentucky Agr. Exp. Sta. Bui. 498. Knox, C. W., 1927. Correlation studies of certain characters upon hatchability and their interrelationships. Poultry Sci. 6: 110-117. Koch, W., 1936. Uber die Einwirkung des Tistikel hormones auf die Befruehtungsfabigkeit des spermos. Klin Wschr. 15: 629-630. Lamoreaux, W. F., 1940. The influence of intensity of egg production upon infertility in the domestic fowl. J. Agr. Res. 61: 191-206. Lamoreaux, W. F., 1942. Environmental temperature and infertility in White Leghorns. Poultry Sci. 21:18-22. Lamoreaux, W. F., 1943. The influence of different amounts of illumination upon the production of semen in the fowl. J. Exp. Zool. 94: 73-95. Nalbandov, A., and L. E. Card, 1943. Effects of stale sperm on fertility and hatchability of chicken eggs. Poultry Sci. 22: 218-226. Nicolaides, C, 1934. Fertility studies in poultry. Poultry Sci. 23: 178-183. Parker, J. E., F. F. McKenzie and H. L. Kempster- 1942. Fertility in the male domestic fowl. Missouri Agr. Exp. Sta. Res. Bui. 347. ShofEner, R. N., and P. C. Smyth, 1944. Response of sexually inactive chicken males to pregnant mare's serum. Poultry Sci. 23: 154-155. Van Uven, M. J., 1935. Method applied by R. Pearl, 1940. Medical Biometry and Statistics, W. B, Saunders Co., Philadelphia, Pa., pp. 456-458. Wilson, W. O., 1948. Egg production rate and fertility in inbred chickens. Poultry Sci. 27: 719 726. COLLEGIATE POULTRY CLUB W. Mickelberry, Silverdale, Washington, a student at the State College of Washington, has been elected President of the National Collegiate Poultry Club. Dr. Stadelman, State College of Washington, has been elected advisor to the group.