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The Effect of Light and Temperature and Their Interaction on the Semen Production of White Leghorn Males
The Effect of Light and Temperature and Their Interaction on the Semen Production of White Leghorn Males P. INGKASUWAN1 AND F. X.
OGASAWARA
University of California, Davis, California (Received for publication February 4, 1966)
MATERIAL AND METHODS
Two tests were run consecutively, using Single Comb White Leghorn males from 1
Present address: Department of Animal Science, Kasetsart University, Bangkok, Thailand.
the University of California random-bred flock. The experiment was designed as a 2 X 2 factorial, using two levels of photoperiods—8 and 14 hours of continuous light per 24 hours—and two levels of ambient temperatures moderate (control) and high (32.2°C). Hereafter, the four groups of each test will be referred to as 14C, 14H, 8C, or 8H, where the number in each notation stands for light hours and the letter (C) for control and (H) for high temperature. Four climatic chambers in the Poultry Husbandry building at U. C. Davis provided the controlled photoperiods and temperatures. Each windowless chamber had a floor 5 meters square, with a ceiling 3 meters above the floor. The chambers were equipped with a draft-free ventilating system and steam heating. Light was provided by incandescent lamps, with the intensity varying from 20 to 100 lux at different locations within the chambers. All cockerels used were raised in a chick room quarantined against visitors. When 11 weeks of age, the birds were transferred into the climatic chambers. Except for the number of light hours received during the rearing period, all conditions for the two sets of cockerels were similar. The first set received 12 hours of light while the second set received 14 hours of light per 24 hours during the rearing period. In the first test 64 males were distributed randomly among the four chambers. These birds were kept for 20 weeks, starting in October 1956. A total of 152
1199
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T IGHT and temperature are two envi-1—' ronmental variables principally affecting certain activities associated with reproductive cycles in birds. The influence of photoperiodism on gonadal activity in various avian species is well reviewed by Farner (1964). However, lighting for increased egg production long preceded any systematic investigation in this field (Staffe, 1951). Temperature has been reported to influence the reproductive activities of starlings (Sturnus vulgaris) (Burger, 1948), white-crowned sparrows (Zonotrichia leucophrys gambelii) (Farner and Wilson, 1957), rooks and robins (Corvus jrugilegus and Erithacus rubecula) (Marshall, 1952), chickens (Gallus gallus domesticus) (Lamoreux, 1943), turkeys (Meleagris gallopavo) (Kosin et al., 1955; Kosin and Mitchell, 1955; Kosin, 1958; Law and Kosin, 1958) and many other birds. Little information has been available, however, concerning the effects of long-term light or temperature, or both, on semen production of domestic chicken males. The present paper presents the results of a study on the effect of long-term, constant short or long photoperiods combined with moderate or high ambient temperatures on the semen production of White Leghorn males.
1200
P. INGKASUWAN AND F. X. OGASAWARA
35 AGE-WEEKS
FIG. 1. Weekly temperatures inside climatic chambers and outdoors. First test, from November 1956 to February 1957. Second test, from April 1957 to May 1958.
birds were used in the second test. After stratification into body weight classes, these also were randomly distributed among the chambers, where they were kept for 61 weeks, starting in April 1957. The arrangement allowed limited comparison between the summer- and the springhatched chickens. Each bird in the climatic chambers was
kept in an individual wire cage. Combs and wattles had been trimmed at eight weeks to prevent any difficulty associated with cage confinement. Regular growing ration was fed up to the time of transfer. Pelleted breeding mash was given without restriction throughout the experimental period. Water was also available at all times. Semen samples were collected from the
TABLE 1.—Average sizes of testes and their seminiferous tubules from males of second test at 16, 20 and 73 •weeks of age, and from males of first test at 32 weeks of age. Group means are given with standard deviations. Key to treatments: Light hours are given as 8 or 14; temperature, as II for 32.2°C. or C for moderate Age in weeks (birds/group) Group 20
16 A. Weight of testes (g.) 14C 14H 8C 8H
(6)
(6) 13.4 17.5 0.7 1.2
+7.7 +4.6 +0.2 +1.3
B. Diameter of seminiferous tubules (mm.) 14C 0.23 + 0.07 14H 0.29 + 0.03 8C 0.10 + 0.05 0.10 + 0.04 8H
22.9 18.5 1.9 4.2
+8.8 +5.2 +1.4 +3.1
0.24 + 0.06 0.24 + 0.04 0.14 + 0.06 0.16 + 0.06
32
73
(10) 21.2 + 20.3 + 27.9 + 14.3 +
5.0 4.7 5.8 6.8
(6) 13.9 12.6 21.0 12.0
+3.2 +5.9 +5.4 +2.2
0.26+0.02 0.24 + 0.03 0.27 + 0.04 0.27 + 0.02
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
30
1201
SEMEN PRODUCTION
RESULTS AND DISCUSSION There was a decided tendency for the temperature in the moderate temperature chambers (control) to follow the outdoor temperature during the warmer months of the year (Fig. 1). Testicular development of birds on 14 hours light followed the expected normal pattern, i.e., attaining maximum size at about 19 weeks of age (Bennett, 1947). Histological examination of seminiferous tubule size (Table 1) indicated a very active stage of spermatogenesis at 20 weeks of age. The 8-hour photoperiod was associated with a delay of several weeks in the initiation of the rapid phase of testicular growth. This was parallel to a delay of sexual development observed by Morris and Fox (1958) in female chickens following reduction of photoperiod. However, the delay did not prevent the testes from attaining normal, functional size. In contrast, a change in photoperiod after sexual maturity does not affect semen production, according to Parker and McCluskey (1964).
B. NUMBER OF SPERM
/ ,' ^,% s'S
/ / /
/
^
"
/ / C. CONCENTRATION
~
/ 4-WEEK PERIODS
FIG. 2. Average of semen volume, spermatozoa concentration, and number of spermatozoa per sample. First test, IS—31 weeks, November 1956 to February 1957.
Our limited data indicate that short day length, combined with moderate ambient temperature, may extend the effective span of the testicular productive cycle in chickens. Figures 2, 3 and 4 give average values of semen production in both tests. The analyses of variance of these values are given in Tables 2, 3, and 4. The data from the second test were divided into periods that would facilitate an evaluation involving physiological cycles and climatic changes. The periods presented are for the early period of semen production (15 to 16 weeks), for the summer period (17 to 36 weeks), and for the more mature periods (12 weeks each). Table 5 gives the analyses of variance of semen production for a 16-week winter period from November to February.
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
cockerels weekly beginning with the fourth week, using the abdominal massage technique of Burrows and Quinn (1937). The volume of each sample was measured with a pipette calibrated at 0.01 ml. The spermatozoal concentration was determined by the light absorption technique described by Carson et al. (1955), and the number of spermatozoa of each sample calculated. In the second test, three groups of six birds randomly selected from each chamber were killed at 16, 20, and 73 weeks, respectively. The testes were weighed and saved for histological observation. Analyses of variance were used to determine significance of temperature, light, and age on measures of semen quality. The average value of each bird per period was the basis of the analyses.
1202
P. INGKASUWAN AND F. X. OGASAWARA
0.3
- SUMMER -
—
""= 8C
s 3 0.2
0.1
J
_L
J_
L
_1_
15
10 4-WEEK PERIODS
FIG. 3. Averages of semen volume. Second test, 15-72 weeks, starting April 1957, ending May 1958.
In this study production of semen was influenced by age of birds, light, temperature, and the light-temperature interaction. Volume of semen, spermatozoal concentration, and number of spermatozoa per sam-
*
/
^
pie were similarly, but not identically, influenced by these factors, During the early period, production of semen was influenced by photoperiod and by temperature mainly through their effects
*
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\
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,.c-
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* *« X''
2 2 -
"'-.
_-- 8H
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/ / i
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10
1
1
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i
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15
4-WEEK PERIODS
FIG. 4. Averages of spermatozoa concentration. Second test, 15-72 weeks, starting April 1957, ending May 1958.
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
_L 1
1203
S E M E N PRODUCTION
TABLE 2.—Analyses of variance of measurements of semen quality obtained from the first test, 15 to 31 weeks (Nov. 1956 to Feb. 1957, WL&) Mean squares
Source of variation
d.f.
Total Light Temperature Interaction Error
41 1 1 1 38
Volume of semen
Concentration
Number of sperm
.0087 .1525 .1652 .0958
.0681f .0039 .0734f .0189
.0081* .0016 .0113** .00118
Notes: ** Significant at 1% level. * Significant at 5% level, f Significant at 10% level.
-Analyses of variance of measurements of semen quality obtained from the second test, 15 to 36 weeks (Apr. 1957 to Sept. 1957, WL
Source of variation
d.f. Volume of semen
A. Early period, 15 to 16 weeks of age Total Light Temperature Interaction Error B. Summer period, 17 to 36 weeks of age Total Light Temperature Interaction Error
Concentration
Number of sperm
146 1 1 1 143
.00801** .00164* .010301** .000281
2.1171** .3986** 2.5751** .0641
.0973** .0346** .1454** .00474
53 1 1 1 50
.000842 .000785 .002302* .000437
.4409f .1772 .6398* .1150
.0335 .00221 .0381 .01295
Note: ** Significant at 1% level. * Significant at 5 % level, f Significant at 10% level.
oj' variance of measurements of semen quality obtained from the second test, 37 to 72 weeks (Sept. 1957 to May 1958, WL&)
TABLE 4.-—Analyses
Source of variation Total Light Temperature Period LXT LXP TXP LXTXP Error (1) Error (2)
Mean squares d.f. 252 1 1 2 1 2 2 2 116 125
Note: ** Significant at 1% level.
Volume of semen
Concentration
.000721 .02009** .000401 .000052 .000217 .000286 .000399 .000909 .000927
.2277 1.2461** .5450 1.2500** .0482 .0138 .0672 .1852 .2354
Number of sperm
E(2>—for any term that includes period (P).
.0003 .3699** .0154 .0785 .0050 .0078 .0088 .0271 .0151
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
TABLE 3 . -
1204
P. INGKASUWAN AND F. X. OGASAWARA TABLE 5.—Analyses of variance of measurements of semen quality obtained from young and old males, 16-week period from {Nov. 1956 to Feb. 1957, WLcT) Source of
Total Light Temperature Age LXA LXT TXA LXTXA Error (1) Error (2)
Mean squares
d{
167 1 1 1 1 1 1 1 77 83
Concentration
Number of sperm
.00183 .01001** .00726* .000496 .006105 .000742 .001128 .001040 .001779
.0478 .0496 1.1431* .1485 .0393 .5746 .1694 .1566 .3031
.0259 .0489 .0007 .0093 .0393 .0952 .0213 .0224 .0259
E(2)—for any term that includes age (A).
on testicular development. Long day length, high ambient temperature, and the light-temperature interaction combined provided a stimulatory effect on testicular development, resulting in early production of semen. After the early period when the gonads of all birds presumably were fully active, the importance of light and temperature on production of semen declined. Only the light-temperature interaction was significantly effective. Examination of the semen production data (Fig. 3 and 4) for the mature periods indicates the depressive effect of high temperature (Table 4) on gonadal activity. The high temperature effect observed in this study differed from those involving a short term, but very high temperature exposure, such as reported by Boone and Huston (1963). The light-temperature interaction also became increasingly important with age, particularly in relation to spermatozoal concentration. Consequently the birds on a short photoperiod and a high temperature regimen (8H) produced semen with the poorest spermatozoal concentration, while those on short day length and moderate temperature (8C) produced semen of very high spermatozoal concentration during the later periods in this study.
The superior performance of the 8C males may be attributed to the fact that short day length and consequent late testicular development extended a benefit comparable to the resting period which avian gonadal tissues require (Marshall, 1950). This rest may be complete in seasonal breeders, but in nonseasonal breeders, such as the domestic chicken, this rest need not be complete. Histological examination of testes from the 8C birds at 73 weeks of age revealed evidence in support of this proposition. The majority of testes from groups 14C, 14H, and 8H had signs similar to those observed by Marshall (1951) during early stages of testis refractoriness. These included the presence of cell debris within the lumina of seminiferous tubules, evidence of fat infiltration, and fewer spermatozoa. In contrast, practically all testes from group 8C still had full spermatogenic activity comparable to Class VI of the spermatogenic stages given by Bartholomew (1949) for the avian testis. This contrast, of course, could not be accounted for by any one single factor. A somewhat similar observation was reported for turkeys (Law and Kosin, 1958), in which a period of temporary rest enabled the males to produce semen of greater volume and higher density. Cyclic variation in production of semen
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
Note: ** Significant at 1% level. * Significant at 5% level.
Volume of semen
SEMEN PRODUCTION
SUMMARY
The effect of light and temperature and their interaction on production of semen by White Leghorns was investigated. A 14-hour photoperiod stimulated gonadal development at an earlier age than did an
8-hour period. The stimulatory effect disappeared with advancing age. An 8-hour photoperiod delayed the start of rapid growth of testes, but did not prevent the testes from attaining normal size. Once the testes were fully developed, they were capable of producing better quality semen than those of males on 14-hour photoperiod under moderate temperature conditions. High ambient temperature (32.2°C.) accelerated slightly the development of testes and the production of semen in the early stages of the experiment, but depressed production later on. Temperature seemed to exert its influence on all phases of semen production investigated, while light appeared to exert its effect on testicular development alone. Slight fluctuations in volume of semen produced under these environmental conditions during the first production year were not statistically significant. Spermatozoal concentration were more pronounced but not significant. The effect of light-temperature interaction on spermatozoal concentration increased with age. Late in the mature period, birds exposed to 8 hours of continuous light per 24 hours and at a high temperature of 32.2°C. had the poorest spermatozoal concentration. Birds exposed to a similar light regimen but at a moderate temperature had the highest spermatozoal concentration. An early, but incomplete, testicular rest, or a partial refractoriness resulting from the high temperature effect and the light-temperature interaction, may have been involved. The combination of high ambient temperature and light is rather similar to the summer environmental conditions when poor fertility in chickens is experienced. It is suggested that this poor fertility during the summer months is due to the poor spermatozoal concentration (and number) resulting from high temperature. The light-temperature interaction also may be important, since in nature the birds are subjected in
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
which could not be explained readily in terms of photoperiod, temperature, or both, was evident during our study. Similar cyclic variations occurred in drakes kept in either constant darkness or continuous light (Benoit et al., 19SS, 1956), and in chickens exposed to simulated summer conditions throughout a year (Wheeler and Andrews, 1943). Greatest variation observed was in spermatozoal concentration, which was strongly influenced by the lighttemperature interaction, and possibly by age. Again, this variation apparently parallels the testicular active and rest periods observed in seasonal breeders. It is quite possible that in nonseasonal breeders the persisting partial rest produces cyclic variation in production of semen. Seasonal decline in fertility of domestic chickens and turkeys has been observed concurrent with the decline in production of semen during the summer months (Parker and McSpadden, 1943; Carson et al., 1955). High ambient temperatures are partially responsible for this decline in fertility (Heywang, 1944). In summer, the basic environmental condition to which males are subjected can be generalized as long but decreasing day length with high temperatures. On the basis of the present study, it is suggested that this environmental condition would force a partial testicular rest after the effects of high ambient temperatures and the light-temperature interaction begin to exert themselves. Therefore, the semen produced would become smaller in volume, lower in sperm concentration, or both, and this alteration of semen quality might account for those incidences of poor fertility occurring during summer months.
1205
1206
P. INGKASUWAN AND F. X. OGASAWARA
summer to decreasing temperature as well as long day lengths. ACKNOWLED GMENT
REFERENCES Bartholomew, G. A., Jr., 1949. The effect of light intensity and day length on reproduction in the English sparrow. Bull. Mus. Comp. Zool. 101: 433-476. Bennett, C. H., 1947. Relation between size and age of the gonads in the fowl from hatching date to sexual maturity. Poultry Sci. 26: 99104. Benoit, J., I. Assenmacher and E. Brard, 1955. Evolution testiculaire du Canard domestique maintenu a Pobscurite totale pendant une longue duree. C. R. Acad. Sci. Paris, 241: 251253. Benoit, J., L. Assenmacher and E. Brard, 1956. Etude de 1'evolution testiculaire du Canard domestique soumis tres jeune a un eclairement artificial permanent pendant deux ans. C. R. Acad. Sci Paris, 242: 3113-3115. Boone, M. A., and T. M. Huston, 1963. Effects of high temperature on semen production and fertility in the domestic fowl. Poultry Sci. 42: 670-675. Burger, J. W., 1948. The relation of external temperature to spermatogenesis in the male starling. J. Exp. Zool. 109: 259-266. Burrows, W. H., and J. P. Quinn, 1937 The collection of spermatozoa from domestic fowl and turkey. Poultry Sci. 16: 19-24. Carson, J. D., F. W. Lorenz and V. S. Asmundson, 1955. Semen production in the turkey male. 1. Seasonal variation. Poultry Sci. 34: 336-343. Farner, D. S., 1964. The photoperiodic control of reproductive cycle in birds. Am. Scientist, 52: 137-156.
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
The authors wish to thank Dr. W. 0. Wilson for his guidance throughout the entire course of these investigations and to acknowledge Dr. Hans Abplanalp for his assistance in statistical procedures. This investigation was presented in a more extended form as a thesis by the senior author in partial fulfillment of the requirement for the degree of Doctor of Philosophy, University of California, Davis.
Farner, D. S., and A. C. Wilson, 1957. A quantitative examination of testicular growth in the white-crowned sparrow. Biol. Bull. 113: 254267. Heywang, B. W., 1944. Fertility and hatchability when the environmental temperature of chickens is high. Poultry Sci. 23: 334-339. Kosin, I. L., 1958. Metabolism of turkey semen as affected by the environment of donor birds. Poultry Sci. 37: 376-388. Kosin, I. L., and M. S. Mitchell, 1955. Ambient temperature as a factor in turkey reproduction. 2. The effect of artificially lowered air temperature on the breeding activity of males in late spring and summer. Poultry Sci. 34: 499-505. Kosin, I. L., M. S. Mitchell and E. St. Pierre, 1955. Ambient temperature as a factor in turkey reproduction. 1. The effect of preheating males and females on their subsequent breeding pen performance. Poultry Sci. 34: 484—496. Lamoreux, W. F., 1943. The influence of different amounts of illumination upon the production of semen in the fowl. J. Exp. Zool. 94: 73-95. Law, G. R. J., and I. L Kosin, 1958. Seasonal reproductive ability of male domestic turkeys as observed under two ambient temperatures. Poultry Sci. 37: 1034-1047. Marshall, A. J., 1950. The mechanism and significance of the refractory period in the avian testis cycle. Nature, 166: 1034-1035. Marshall, A. J., 1951. The refractory period of testis rhythm in birds and its possible bearing on breeding and migration. Wilson Bull. 63: 238-261. Marshall, A. J., 1952. The interstitial cycle in relation to autumn and winter sexual behavior in birds. Proc. Zool. Soc. London, 121-A: 727— 740. Morris, T. R., and S. Fox, 1958. Light and sexual maturity in the domestic fowl. Nature, 181: 1453-1454. Parker, J. E., and W. H. McCluskey, 1964. The effect of the length of daily light periods on the volume and fertilizing capacity of semen from male chickens. Poultry Sci. 43: 1401-1405. Parker, J. E., and B. J. McSpadden, 1943. Seasonal variation in semen production in domestic fowls. Poultry Sci. 22: 142-147. Staffe, V. A., 1951. Belichtung and Legeleistung bein Huhn. Experentia, 7 : 399-400. Wheeler, N. C , and F. N. Andrews, 1943. The influence of season on semen production in the domestic fowl. Poultry Sci. 22: 361-367.
OGASAWARA
University of California, Davis, California (Received for publication February 4, 1966)
MATERIAL AND METHODS
Two tests were run consecutively, using Single Comb White Leghorn males from 1
Present address: Department of Animal Science, Kasetsart University, Bangkok, Thailand.
the University of California random-bred flock. The experiment was designed as a 2 X 2 factorial, using two levels of photoperiods—8 and 14 hours of continuous light per 24 hours—and two levels of ambient temperatures moderate (control) and high (32.2°C). Hereafter, the four groups of each test will be referred to as 14C, 14H, 8C, or 8H, where the number in each notation stands for light hours and the letter (C) for control and (H) for high temperature. Four climatic chambers in the Poultry Husbandry building at U. C. Davis provided the controlled photoperiods and temperatures. Each windowless chamber had a floor 5 meters square, with a ceiling 3 meters above the floor. The chambers were equipped with a draft-free ventilating system and steam heating. Light was provided by incandescent lamps, with the intensity varying from 20 to 100 lux at different locations within the chambers. All cockerels used were raised in a chick room quarantined against visitors. When 11 weeks of age, the birds were transferred into the climatic chambers. Except for the number of light hours received during the rearing period, all conditions for the two sets of cockerels were similar. The first set received 12 hours of light while the second set received 14 hours of light per 24 hours during the rearing period. In the first test 64 males were distributed randomly among the four chambers. These birds were kept for 20 weeks, starting in October 1956. A total of 152
1199
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
T IGHT and temperature are two envi-1—' ronmental variables principally affecting certain activities associated with reproductive cycles in birds. The influence of photoperiodism on gonadal activity in various avian species is well reviewed by Farner (1964). However, lighting for increased egg production long preceded any systematic investigation in this field (Staffe, 1951). Temperature has been reported to influence the reproductive activities of starlings (Sturnus vulgaris) (Burger, 1948), white-crowned sparrows (Zonotrichia leucophrys gambelii) (Farner and Wilson, 1957), rooks and robins (Corvus jrugilegus and Erithacus rubecula) (Marshall, 1952), chickens (Gallus gallus domesticus) (Lamoreux, 1943), turkeys (Meleagris gallopavo) (Kosin et al., 1955; Kosin and Mitchell, 1955; Kosin, 1958; Law and Kosin, 1958) and many other birds. Little information has been available, however, concerning the effects of long-term light or temperature, or both, on semen production of domestic chicken males. The present paper presents the results of a study on the effect of long-term, constant short or long photoperiods combined with moderate or high ambient temperatures on the semen production of White Leghorn males.
1200
P. INGKASUWAN AND F. X. OGASAWARA
35 AGE-WEEKS
FIG. 1. Weekly temperatures inside climatic chambers and outdoors. First test, from November 1956 to February 1957. Second test, from April 1957 to May 1958.
birds were used in the second test. After stratification into body weight classes, these also were randomly distributed among the chambers, where they were kept for 61 weeks, starting in April 1957. The arrangement allowed limited comparison between the summer- and the springhatched chickens. Each bird in the climatic chambers was
kept in an individual wire cage. Combs and wattles had been trimmed at eight weeks to prevent any difficulty associated with cage confinement. Regular growing ration was fed up to the time of transfer. Pelleted breeding mash was given without restriction throughout the experimental period. Water was also available at all times. Semen samples were collected from the
TABLE 1.—Average sizes of testes and their seminiferous tubules from males of second test at 16, 20 and 73 •weeks of age, and from males of first test at 32 weeks of age. Group means are given with standard deviations. Key to treatments: Light hours are given as 8 or 14; temperature, as II for 32.2°C. or C for moderate Age in weeks (birds/group) Group 20
16 A. Weight of testes (g.) 14C 14H 8C 8H
(6)
(6) 13.4 17.5 0.7 1.2
+7.7 +4.6 +0.2 +1.3
B. Diameter of seminiferous tubules (mm.) 14C 0.23 + 0.07 14H 0.29 + 0.03 8C 0.10 + 0.05 0.10 + 0.04 8H
22.9 18.5 1.9 4.2
+8.8 +5.2 +1.4 +3.1
0.24 + 0.06 0.24 + 0.04 0.14 + 0.06 0.16 + 0.06
32
73
(10) 21.2 + 20.3 + 27.9 + 14.3 +
5.0 4.7 5.8 6.8
(6) 13.9 12.6 21.0 12.0
+3.2 +5.9 +5.4 +2.2
0.26+0.02 0.24 + 0.03 0.27 + 0.04 0.27 + 0.02
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
30
1201
SEMEN PRODUCTION
RESULTS AND DISCUSSION There was a decided tendency for the temperature in the moderate temperature chambers (control) to follow the outdoor temperature during the warmer months of the year (Fig. 1). Testicular development of birds on 14 hours light followed the expected normal pattern, i.e., attaining maximum size at about 19 weeks of age (Bennett, 1947). Histological examination of seminiferous tubule size (Table 1) indicated a very active stage of spermatogenesis at 20 weeks of age. The 8-hour photoperiod was associated with a delay of several weeks in the initiation of the rapid phase of testicular growth. This was parallel to a delay of sexual development observed by Morris and Fox (1958) in female chickens following reduction of photoperiod. However, the delay did not prevent the testes from attaining normal, functional size. In contrast, a change in photoperiod after sexual maturity does not affect semen production, according to Parker and McCluskey (1964).
B. NUMBER OF SPERM
/ ,' ^,% s'S
/ / /
/
^
"
/ / C. CONCENTRATION
~
/ 4-WEEK PERIODS
FIG. 2. Average of semen volume, spermatozoa concentration, and number of spermatozoa per sample. First test, IS—31 weeks, November 1956 to February 1957.
Our limited data indicate that short day length, combined with moderate ambient temperature, may extend the effective span of the testicular productive cycle in chickens. Figures 2, 3 and 4 give average values of semen production in both tests. The analyses of variance of these values are given in Tables 2, 3, and 4. The data from the second test were divided into periods that would facilitate an evaluation involving physiological cycles and climatic changes. The periods presented are for the early period of semen production (15 to 16 weeks), for the summer period (17 to 36 weeks), and for the more mature periods (12 weeks each). Table 5 gives the analyses of variance of semen production for a 16-week winter period from November to February.
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
cockerels weekly beginning with the fourth week, using the abdominal massage technique of Burrows and Quinn (1937). The volume of each sample was measured with a pipette calibrated at 0.01 ml. The spermatozoal concentration was determined by the light absorption technique described by Carson et al. (1955), and the number of spermatozoa of each sample calculated. In the second test, three groups of six birds randomly selected from each chamber were killed at 16, 20, and 73 weeks, respectively. The testes were weighed and saved for histological observation. Analyses of variance were used to determine significance of temperature, light, and age on measures of semen quality. The average value of each bird per period was the basis of the analyses.
1202
P. INGKASUWAN AND F. X. OGASAWARA
0.3
- SUMMER -
—
""= 8C
s 3 0.2
0.1
J
_L
J_
L
_1_
15
10 4-WEEK PERIODS
FIG. 3. Averages of semen volume. Second test, 15-72 weeks, starting April 1957, ending May 1958.
In this study production of semen was influenced by age of birds, light, temperature, and the light-temperature interaction. Volume of semen, spermatozoal concentration, and number of spermatozoa per sam-
*
/
^
pie were similarly, but not identically, influenced by these factors, During the early period, production of semen was influenced by photoperiod and by temperature mainly through their effects
*
/ ^
\
/
/'r\y
N^
w/// ..^
f^
s s
/
,.c-
^V7
* *« X''
2 2 -
"'-.
_-- 8H
. • - " " /
/ / i
<
i
i
i
I
I
I
!
!
10
1
1
!
i
!
15
4-WEEK PERIODS
FIG. 4. Averages of spermatozoa concentration. Second test, 15-72 weeks, starting April 1957, ending May 1958.
Downloaded from http://ps.oxfordjournals.org/ at Gazi Universitesi on May 4, 2015
_L 1
1203
S E M E N PRODUCTION
TABLE 2.—Analyses of variance of measurements of semen quality obtained from the first test, 15 to 31 weeks (Nov. 1956 to Feb. 1957, WL&) Mean squares
Source of variation
d.f.
Total Light Temperature Interaction Error
41 1 1 1 38
Volume of semen
Concentration
Number of sperm
.0087 .1525 .1652 .0958
.0681f .0039 .0734f .0189
.0081* .0016 .0113** .00118
Notes: ** Significant at 1% level. * Significant at 5% level, f Significant at 10% level.
-Analyses of variance of measurements of semen quality obtained from the second test, 15 to 36 weeks (Apr. 1957 to Sept. 1957, WL
Source of variation
d.f. Volume of semen
A. Early period, 15 to 16 weeks of age Total Light Temperature Interaction Error B. Summer period, 17 to 36 weeks of age Total Light Temperature Interaction Error
Concentration
Number of sperm
146 1 1 1 143
.00801** .00164* .010301** .000281
2.1171** .3986** 2.5751** .0641
.0973** .0346** .1454** .00474
53 1 1 1 50
.000842 .000785 .002302* .000437
.4409f .1772 .6398* .1150
.0335 .00221 .0381 .01295
Note: ** Significant at 1% level. * Significant at 5 % level, f Significant at 10% level.
oj' variance of measurements of semen quality obtained from the second test, 37 to 72 weeks (Sept. 1957 to May 1958, WL&)
TABLE 4.-—Analyses
Source of variation Total Light Temperature Period LXT LXP TXP LXTXP Error (1) Error (2)
Mean squares d.f. 252 1 1 2 1 2 2 2 116 125
Note: ** Significant at 1% level.
Volume of semen
Concentration
.000721 .02009** .000401 .000052 .000217 .000286 .000399 .000909 .000927
.2277 1.2461** .5450 1.2500** .0482 .0138 .0672 .1852 .2354
Number of sperm
E(2>—for any term that includes period (P).
.0003 .3699** .0154 .0785 .0050 .0078 .0088 .0271 .0151
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TABLE 3 . -
1204
P. INGKASUWAN AND F. X. OGASAWARA TABLE 5.—Analyses of variance of measurements of semen quality obtained from young and old males, 16-week period from {Nov. 1956 to Feb. 1957, WLcT) Source of
Total Light Temperature Age LXA LXT TXA LXTXA Error (1) Error (2)
Mean squares
d{
167 1 1 1 1 1 1 1 77 83
Concentration
Number of sperm
.00183 .01001** .00726* .000496 .006105 .000742 .001128 .001040 .001779
.0478 .0496 1.1431* .1485 .0393 .5746 .1694 .1566 .3031
.0259 .0489 .0007 .0093 .0393 .0952 .0213 .0224 .0259
E(2)—for any term that includes age (A).
on testicular development. Long day length, high ambient temperature, and the light-temperature interaction combined provided a stimulatory effect on testicular development, resulting in early production of semen. After the early period when the gonads of all birds presumably were fully active, the importance of light and temperature on production of semen declined. Only the light-temperature interaction was significantly effective. Examination of the semen production data (Fig. 3 and 4) for the mature periods indicates the depressive effect of high temperature (Table 4) on gonadal activity. The high temperature effect observed in this study differed from those involving a short term, but very high temperature exposure, such as reported by Boone and Huston (1963). The light-temperature interaction also became increasingly important with age, particularly in relation to spermatozoal concentration. Consequently the birds on a short photoperiod and a high temperature regimen (8H) produced semen with the poorest spermatozoal concentration, while those on short day length and moderate temperature (8C) produced semen of very high spermatozoal concentration during the later periods in this study.
The superior performance of the 8C males may be attributed to the fact that short day length and consequent late testicular development extended a benefit comparable to the resting period which avian gonadal tissues require (Marshall, 1950). This rest may be complete in seasonal breeders, but in nonseasonal breeders, such as the domestic chicken, this rest need not be complete. Histological examination of testes from the 8C birds at 73 weeks of age revealed evidence in support of this proposition. The majority of testes from groups 14C, 14H, and 8H had signs similar to those observed by Marshall (1951) during early stages of testis refractoriness. These included the presence of cell debris within the lumina of seminiferous tubules, evidence of fat infiltration, and fewer spermatozoa. In contrast, practically all testes from group 8C still had full spermatogenic activity comparable to Class VI of the spermatogenic stages given by Bartholomew (1949) for the avian testis. This contrast, of course, could not be accounted for by any one single factor. A somewhat similar observation was reported for turkeys (Law and Kosin, 1958), in which a period of temporary rest enabled the males to produce semen of greater volume and higher density. Cyclic variation in production of semen
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Note: ** Significant at 1% level. * Significant at 5% level.
Volume of semen
SEMEN PRODUCTION
SUMMARY
The effect of light and temperature and their interaction on production of semen by White Leghorns was investigated. A 14-hour photoperiod stimulated gonadal development at an earlier age than did an
8-hour period. The stimulatory effect disappeared with advancing age. An 8-hour photoperiod delayed the start of rapid growth of testes, but did not prevent the testes from attaining normal size. Once the testes were fully developed, they were capable of producing better quality semen than those of males on 14-hour photoperiod under moderate temperature conditions. High ambient temperature (32.2°C.) accelerated slightly the development of testes and the production of semen in the early stages of the experiment, but depressed production later on. Temperature seemed to exert its influence on all phases of semen production investigated, while light appeared to exert its effect on testicular development alone. Slight fluctuations in volume of semen produced under these environmental conditions during the first production year were not statistically significant. Spermatozoal concentration were more pronounced but not significant. The effect of light-temperature interaction on spermatozoal concentration increased with age. Late in the mature period, birds exposed to 8 hours of continuous light per 24 hours and at a high temperature of 32.2°C. had the poorest spermatozoal concentration. Birds exposed to a similar light regimen but at a moderate temperature had the highest spermatozoal concentration. An early, but incomplete, testicular rest, or a partial refractoriness resulting from the high temperature effect and the light-temperature interaction, may have been involved. The combination of high ambient temperature and light is rather similar to the summer environmental conditions when poor fertility in chickens is experienced. It is suggested that this poor fertility during the summer months is due to the poor spermatozoal concentration (and number) resulting from high temperature. The light-temperature interaction also may be important, since in nature the birds are subjected in
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which could not be explained readily in terms of photoperiod, temperature, or both, was evident during our study. Similar cyclic variations occurred in drakes kept in either constant darkness or continuous light (Benoit et al., 19SS, 1956), and in chickens exposed to simulated summer conditions throughout a year (Wheeler and Andrews, 1943). Greatest variation observed was in spermatozoal concentration, which was strongly influenced by the lighttemperature interaction, and possibly by age. Again, this variation apparently parallels the testicular active and rest periods observed in seasonal breeders. It is quite possible that in nonseasonal breeders the persisting partial rest produces cyclic variation in production of semen. Seasonal decline in fertility of domestic chickens and turkeys has been observed concurrent with the decline in production of semen during the summer months (Parker and McSpadden, 1943; Carson et al., 1955). High ambient temperatures are partially responsible for this decline in fertility (Heywang, 1944). In summer, the basic environmental condition to which males are subjected can be generalized as long but decreasing day length with high temperatures. On the basis of the present study, it is suggested that this environmental condition would force a partial testicular rest after the effects of high ambient temperatures and the light-temperature interaction begin to exert themselves. Therefore, the semen produced would become smaller in volume, lower in sperm concentration, or both, and this alteration of semen quality might account for those incidences of poor fertility occurring during summer months.
1205
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P. INGKASUWAN AND F. X. OGASAWARA
summer to decreasing temperature as well as long day lengths. ACKNOWLED GMENT
REFERENCES Bartholomew, G. A., Jr., 1949. The effect of light intensity and day length on reproduction in the English sparrow. Bull. Mus. Comp. Zool. 101: 433-476. Bennett, C. H., 1947. Relation between size and age of the gonads in the fowl from hatching date to sexual maturity. Poultry Sci. 26: 99104. Benoit, J., I. Assenmacher and E. Brard, 1955. Evolution testiculaire du Canard domestique maintenu a Pobscurite totale pendant une longue duree. C. R. Acad. Sci. Paris, 241: 251253. Benoit, J., L. Assenmacher and E. Brard, 1956. Etude de 1'evolution testiculaire du Canard domestique soumis tres jeune a un eclairement artificial permanent pendant deux ans. C. R. Acad. Sci Paris, 242: 3113-3115. Boone, M. A., and T. M. Huston, 1963. Effects of high temperature on semen production and fertility in the domestic fowl. Poultry Sci. 42: 670-675. Burger, J. W., 1948. The relation of external temperature to spermatogenesis in the male starling. J. Exp. Zool. 109: 259-266. Burrows, W. H., and J. P. Quinn, 1937 The collection of spermatozoa from domestic fowl and turkey. Poultry Sci. 16: 19-24. Carson, J. D., F. W. Lorenz and V. S. Asmundson, 1955. Semen production in the turkey male. 1. Seasonal variation. Poultry Sci. 34: 336-343. Farner, D. S., 1964. The photoperiodic control of reproductive cycle in birds. Am. Scientist, 52: 137-156.
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The authors wish to thank Dr. W. 0. Wilson for his guidance throughout the entire course of these investigations and to acknowledge Dr. Hans Abplanalp for his assistance in statistical procedures. This investigation was presented in a more extended form as a thesis by the senior author in partial fulfillment of the requirement for the degree of Doctor of Philosophy, University of California, Davis.
Farner, D. S., and A. C. Wilson, 1957. A quantitative examination of testicular growth in the white-crowned sparrow. Biol. Bull. 113: 254267. Heywang, B. W., 1944. Fertility and hatchability when the environmental temperature of chickens is high. Poultry Sci. 23: 334-339. Kosin, I. L., 1958. Metabolism of turkey semen as affected by the environment of donor birds. Poultry Sci. 37: 376-388. Kosin, I. L., and M. S. Mitchell, 1955. Ambient temperature as a factor in turkey reproduction. 2. The effect of artificially lowered air temperature on the breeding activity of males in late spring and summer. Poultry Sci. 34: 499-505. Kosin, I. L., M. S. Mitchell and E. St. Pierre, 1955. Ambient temperature as a factor in turkey reproduction. 1. The effect of preheating males and females on their subsequent breeding pen performance. Poultry Sci. 34: 484—496. Lamoreux, W. F., 1943. The influence of different amounts of illumination upon the production of semen in the fowl. J. Exp. Zool. 94: 73-95. Law, G. R. J., and I. L Kosin, 1958. Seasonal reproductive ability of male domestic turkeys as observed under two ambient temperatures. Poultry Sci. 37: 1034-1047. Marshall, A. J., 1950. The mechanism and significance of the refractory period in the avian testis cycle. Nature, 166: 1034-1035. Marshall, A. J., 1951. The refractory period of testis rhythm in birds and its possible bearing on breeding and migration. Wilson Bull. 63: 238-261. Marshall, A. J., 1952. The interstitial cycle in relation to autumn and winter sexual behavior in birds. Proc. Zool. Soc. London, 121-A: 727— 740. Morris, T. R., and S. Fox, 1958. Light and sexual maturity in the domestic fowl. Nature, 181: 1453-1454. Parker, J. E., and W. H. McCluskey, 1964. The effect of the length of daily light periods on the volume and fertilizing capacity of semen from male chickens. Poultry Sci. 43: 1401-1405. Parker, J. E., and B. J. McSpadden, 1943. Seasonal variation in semen production in domestic fowls. Poultry Sci. 22: 142-147. Staffe, V. A., 1951. Belichtung and Legeleistung bein Huhn. Experentia, 7 : 399-400. Wheeler, N. C , and F. N. Andrews, 1943. The influence of season on semen production in the domestic fowl. Poultry Sci. 22: 361-367.