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Research Note: The Effects of Switching Males Among Caged Females on Egg Production and Hatchability in Japanese Quail
Research Note: The Effects of Switching Males Among Caged Females on Egg Production and Hatchability in Japanese Quail SABINE G. GEBHARDT-HENRICH1 and HENRY L. MARKS USDA, Agricultural Research Service, Southeast Poultry Research Laboratory, do University of Georgia, 107 Livestock-Poultry Building, Athens, Georgia 30602
ABSTRACT For a half-sib mating design each male was switched among four females that were kept in separate cages once a day, so that each female was paired with a male every 4th day. Control males were permanently paired with one female each. There was some evidence that the mating system involving switching of males among females decreased egg production and hatchability by about 9 and 16%, respectively. The present study argues, however, that the slight decrease in hatchability, which was only present in some males, does not prevent the application of this method for half-sib breeding designs to estimate heritabilities. (Key words: Japanese quail, mating system, hatchability, egg production, half-sib design) 1991 Poultry Science 70:1845-1847 INTRODUCTION
The Japanese quail (Coturnix coturnix japonica) has become a commonly used study animal for selection experiments in poultry science (e.g., Marks and Lepore, 1968; Marks, 1971, 1978; Bacon and Nestor, 1983). Its advantages are small size and short generation span. One common method in quantitative genetics for the estimation of heritability is the halfsib analysis (Falconer, 1981) in which one sire is mated to several dams. Artificial insemination, which is routinely carried out in chickens, has proven more difficult in quail (Marks and Lepore, 1965). When one male is housed together with three females that differ in their eggs' color patterns, the identity of the eggs can be determined with high accuracy (Jones et al., 1964). This method, however, becomes unreliable when more than three females are housed together (Jones et al., 1964). The other possibility is to naturally mate a male to several females by switching males among the females instead of pairing them permanently. Lower fertilities have been reported for this method (Camci, 1989) as well as when males
'Swiss National Science Foundation Fellow. Current address: Zoologisches Institut, Rheinsprung 9, CH-4051 Basel, Switzerland. 2 Purina Mills, Inc., St. Louis, MO 63166.
were permanently housed with several females (Woodard and Abplanalp, 1967). However, Kiker and Siegel (1972) found that when a male was placed singly in a pen with two female quail for a 1-h period and then removed, fecundity was as great as when a male was placed for either a 2-h or 24-h period. The present study compared the hatchability of paired matings with hatchabilities when males were switched among females in separate cages. MATERIALS AND METHODS
The quail used in the current study have been randomly mated for 32 generations (Marks, 1971). One hundred and twenty pairs were kept in separate cages prior to the experiment and were between 3 and 6 mo of age. Water was available at all times and quail had ad libitum access to a 20% CP commercial gamebird breeder diet.2 In the first experiment, all 120 cages (18.5 cm long x 21 cm wide x 18.5 cm high) were divided into 30 experimental groups of four adjacent cages. All males except the first in each group were removed. Four days after the removal, males were switched among the four cages in their group before 0830 h each day for 21 days. During this time eggs were marked, collected daily, and stored in a chilled room (10 C) before incubation. After 18 days of incubation, hatched chicks were counted. Af-
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Downloaded from http://ps.oxfordjournals.org/ at Rutgers University Libraries/Technical Services on June 5, 2015
(Received for publication February 25, 1991)
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GEBHARDT-HENRICH AND MARKS TABLE 1. Hatchabitities (%) of eggs averaged over the four females mated to each of 15 males in Experiment 2 Male
Hatchability
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
96 49 88 52 71 58 68 83 0 44 88 79 80 68 0
Statistical Analyses Females that laid fewer than six eggs were excluded from the analyses of hatchability. Hatchability was calculated as number of hatchlings divided by the number of eggs. Because the distributions of this measure as well as of egg number were highly skewed and transformations did not achieve normal distributions, nonparametric Kruskal-Wallis tests were used throughout. When the influence of males was tested, only data from the rotational male treatment were used, where one male was mated to four different females. RESULTS
In the first experiment the number of eggs laid and the hatchability were not significantly different. Control group females laid 18.7 eggs with a 75% hatch, whereas in the rotational male group, the females laid 18.1 eggs with a 74% hatch. The correlation between the hatchability of eggs from females that were mated to the same males in both treatments (one-fourth of all) was high and significant (Pearson r = .66, df = 29, P = .0001). In the second experiment, however, females that were permanently paired laid one more egg (12.3 versus 11.2) on average and the difference between treatments was significant at the P<.05 level. The hatchability of eggs from permanent pairs was 83% but that of birds that were paired only every 4th day was 70%. This difference of 13% was significant at the P<.0004 level. The identity of the male had no influence on the number of eggs a female
laid (P = .13), but it had a significant effect on their hatchability (%2 = 36.39, df = 14, P = .0009). The eggs of females mated to one-third of all switched males had average hatchabilities below 50%, two sets of females had no eggs that hatched (Table 1). DISCUSSION
Despite the small decrease of 9% in egg production of females that were only paired every 4th day and a 16% decrease in hatchability in the second experiment, half-sib designs that involve switching of males among females appears to be feasible. In the first experiment with a different set of quail there were no significant differences in egg production or hatchability. However, treatments in this experiment were confounded with a possible age effect. When the quail were subjected to the control treatment (permanent pairs), they were about 4 wk older. Fertility is known to decrease wim age in quail, although this decrease was demonstrated in quail older than 6 mo (Woodard and Abplanalp, 1967). The quail used in the present study were younger than 6 mo, but it cannot be ruled out that the older age resulted in lower hatchability when quail were permanently paired in the first experiment. There were large differences in the hatchability among switched males in the second experiment. Some males did not seem to be
Downloaded from http://ps.oxfordjournals.org/ at Rutgers University Libraries/Technical Services on June 5, 2015
terwards, all males were returned and permanently paired with their original females. Again, eggs were collected for 21 days, incubated, and the hatchability was determined. The second experiment was performed with quail from the 33rd generation. In this experiment quail from 120 cages were divided into 15 groups consisting of four treatment cages alternated wim four control cages. In each rotational experimental group all males but one were removed; in the control groups quail remained permanently paired. Otherwise, the experimental procedures were the same as in the first experiment, except that the removal of males was about 10 days prior to the initiation of switching of males and eggs were collected for 14 instead of 21 days.
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RESEARCH NOTE
ACKNOWLEDGMENTS
The authors thank Rolan Malcolm, Frank McDonald, and Keith Crawford for their help in the care of the birds. The support of the Swiss National Science Foundation to S. G. Gebhardt-Henrich is acknowledged.
REFERENCES Bacon, W. L., and K. E. Nestor, 1983. Divergent selection for body weight and yolk precursor in Cotumix coturnix japonica. 5. Correlated responses in adult body weight, liver weight, ovarian follicle production, and carcass composition of laying hens. Poultry Sci. 62:1876-1884. Camci, 6., 1989. Ziichterische Beeinflussung der Kdrperzusammensetzung bei Wachteln. Ph.D. dissertation, UniversitSt Hohenheim. Stuttgart, Hohenheim, Germany. Falconer, D. S., 1981. Introduction to Quantitative Genetics, 2nd edition. Ronald Press Co., New York, NY. Jones, J. M, M. A. Maloney, and J. C. Giibreath, 1964. Size, shape and color pattern as criteria for identifying Coturnix eggs. Poultry Sci. 43: 1292-1294. Kiker, J. T., and P. B. Siegel, 1972. Fecundity of Coturnix coturnix japonica as influenced by daily mating regimes. Page 205 in: Proceedings of Southern Agricultural Workers Inc., 69th Annual Convention, Richmond, VA. Marks, H. L., 1971. Selection for four-week body weight in Japanese Quail under two nutritional environments. Poultry Sci. 50:931-937. Marks, H. L., 1978. Long term selection for four-week body weight in Japanese quail under different nutritional environments. Theor. Appl. Genet. 52: 105-111. Marks, H. L., and P. D. Lepore, 1965. A procedure for artificial insemination of Japanese Quail. Poultry Sci. 44:1001-1003. Marks, H. L., and P. D. Lepore, 1968. Growth rate inheritance in Japanese Quail. 2. Early responses to selection under different nutritional environments. Poultry Sci. 47:1540-1546. Woodard, A. E., and H. Abplanalp, 1967. The effects of mating ratio and age on fertility and hatchability in the Japanese quail. Poultry Sci. 46:383-388.
Downloaded from http://ps.oxfordjournals.org/ at Rutgers University Libraries/Technical Services on June 5, 2015
affected by the switching, whereas others obviously had lower fertilization rates when switched (Table 1). Stress caused by this switching may have been responsible for the decrease in fertilization of eggs for some males (Camci, 1989). Kiker and Siegel (1972) also suggested that social interactions between sexes during allocated mating times may result in different stress levels. It is presumed that the treatment affected mating activity. The identity of the male did not influence egg production of the female. Females that were only mated every 4th day, however, laid fewer eggs than permanently paired females in the second experiment. It is not clear whether this decrease in egg production was also caused by stress or by the absence of a male during 75% of the time. Mean hatchabilities of eggs from the switched males treatment were similar in Experiments 1 and 2. These data indicate that by collecting eggs over a 21-day period it is possible to obtain full-sib families of 12 to 14 individuals. Families of this size should be adequate for half-sib breeding designs to estimate heritabilities in Japanese quail.
ABSTRACT For a half-sib mating design each male was switched among four females that were kept in separate cages once a day, so that each female was paired with a male every 4th day. Control males were permanently paired with one female each. There was some evidence that the mating system involving switching of males among females decreased egg production and hatchability by about 9 and 16%, respectively. The present study argues, however, that the slight decrease in hatchability, which was only present in some males, does not prevent the application of this method for half-sib breeding designs to estimate heritabilities. (Key words: Japanese quail, mating system, hatchability, egg production, half-sib design) 1991 Poultry Science 70:1845-1847 INTRODUCTION
The Japanese quail (Coturnix coturnix japonica) has become a commonly used study animal for selection experiments in poultry science (e.g., Marks and Lepore, 1968; Marks, 1971, 1978; Bacon and Nestor, 1983). Its advantages are small size and short generation span. One common method in quantitative genetics for the estimation of heritability is the halfsib analysis (Falconer, 1981) in which one sire is mated to several dams. Artificial insemination, which is routinely carried out in chickens, has proven more difficult in quail (Marks and Lepore, 1965). When one male is housed together with three females that differ in their eggs' color patterns, the identity of the eggs can be determined with high accuracy (Jones et al., 1964). This method, however, becomes unreliable when more than three females are housed together (Jones et al., 1964). The other possibility is to naturally mate a male to several females by switching males among the females instead of pairing them permanently. Lower fertilities have been reported for this method (Camci, 1989) as well as when males
'Swiss National Science Foundation Fellow. Current address: Zoologisches Institut, Rheinsprung 9, CH-4051 Basel, Switzerland. 2 Purina Mills, Inc., St. Louis, MO 63166.
were permanently housed with several females (Woodard and Abplanalp, 1967). However, Kiker and Siegel (1972) found that when a male was placed singly in a pen with two female quail for a 1-h period and then removed, fecundity was as great as when a male was placed for either a 2-h or 24-h period. The present study compared the hatchability of paired matings with hatchabilities when males were switched among females in separate cages. MATERIALS AND METHODS
The quail used in the current study have been randomly mated for 32 generations (Marks, 1971). One hundred and twenty pairs were kept in separate cages prior to the experiment and were between 3 and 6 mo of age. Water was available at all times and quail had ad libitum access to a 20% CP commercial gamebird breeder diet.2 In the first experiment, all 120 cages (18.5 cm long x 21 cm wide x 18.5 cm high) were divided into 30 experimental groups of four adjacent cages. All males except the first in each group were removed. Four days after the removal, males were switched among the four cages in their group before 0830 h each day for 21 days. During this time eggs were marked, collected daily, and stored in a chilled room (10 C) before incubation. After 18 days of incubation, hatched chicks were counted. Af-
1845
Downloaded from http://ps.oxfordjournals.org/ at Rutgers University Libraries/Technical Services on June 5, 2015
(Received for publication February 25, 1991)
1846
GEBHARDT-HENRICH AND MARKS TABLE 1. Hatchabitities (%) of eggs averaged over the four females mated to each of 15 males in Experiment 2 Male
Hatchability
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
96 49 88 52 71 58 68 83 0 44 88 79 80 68 0
Statistical Analyses Females that laid fewer than six eggs were excluded from the analyses of hatchability. Hatchability was calculated as number of hatchlings divided by the number of eggs. Because the distributions of this measure as well as of egg number were highly skewed and transformations did not achieve normal distributions, nonparametric Kruskal-Wallis tests were used throughout. When the influence of males was tested, only data from the rotational male treatment were used, where one male was mated to four different females. RESULTS
In the first experiment the number of eggs laid and the hatchability were not significantly different. Control group females laid 18.7 eggs with a 75% hatch, whereas in the rotational male group, the females laid 18.1 eggs with a 74% hatch. The correlation between the hatchability of eggs from females that were mated to the same males in both treatments (one-fourth of all) was high and significant (Pearson r = .66, df = 29, P = .0001). In the second experiment, however, females that were permanently paired laid one more egg (12.3 versus 11.2) on average and the difference between treatments was significant at the P<.05 level. The hatchability of eggs from permanent pairs was 83% but that of birds that were paired only every 4th day was 70%. This difference of 13% was significant at the P<.0004 level. The identity of the male had no influence on the number of eggs a female
laid (P = .13), but it had a significant effect on their hatchability (%2 = 36.39, df = 14, P = .0009). The eggs of females mated to one-third of all switched males had average hatchabilities below 50%, two sets of females had no eggs that hatched (Table 1). DISCUSSION
Despite the small decrease of 9% in egg production of females that were only paired every 4th day and a 16% decrease in hatchability in the second experiment, half-sib designs that involve switching of males among females appears to be feasible. In the first experiment with a different set of quail there were no significant differences in egg production or hatchability. However, treatments in this experiment were confounded with a possible age effect. When the quail were subjected to the control treatment (permanent pairs), they were about 4 wk older. Fertility is known to decrease wim age in quail, although this decrease was demonstrated in quail older than 6 mo (Woodard and Abplanalp, 1967). The quail used in the present study were younger than 6 mo, but it cannot be ruled out that the older age resulted in lower hatchability when quail were permanently paired in the first experiment. There were large differences in the hatchability among switched males in the second experiment. Some males did not seem to be
Downloaded from http://ps.oxfordjournals.org/ at Rutgers University Libraries/Technical Services on June 5, 2015
terwards, all males were returned and permanently paired with their original females. Again, eggs were collected for 21 days, incubated, and the hatchability was determined. The second experiment was performed with quail from the 33rd generation. In this experiment quail from 120 cages were divided into 15 groups consisting of four treatment cages alternated wim four control cages. In each rotational experimental group all males but one were removed; in the control groups quail remained permanently paired. Otherwise, the experimental procedures were the same as in the first experiment, except that the removal of males was about 10 days prior to the initiation of switching of males and eggs were collected for 14 instead of 21 days.
1847
RESEARCH NOTE
ACKNOWLEDGMENTS
The authors thank Rolan Malcolm, Frank McDonald, and Keith Crawford for their help in the care of the birds. The support of the Swiss National Science Foundation to S. G. Gebhardt-Henrich is acknowledged.
REFERENCES Bacon, W. L., and K. E. Nestor, 1983. Divergent selection for body weight and yolk precursor in Cotumix coturnix japonica. 5. Correlated responses in adult body weight, liver weight, ovarian follicle production, and carcass composition of laying hens. Poultry Sci. 62:1876-1884. Camci, 6., 1989. Ziichterische Beeinflussung der Kdrperzusammensetzung bei Wachteln. Ph.D. dissertation, UniversitSt Hohenheim. Stuttgart, Hohenheim, Germany. Falconer, D. S., 1981. Introduction to Quantitative Genetics, 2nd edition. Ronald Press Co., New York, NY. Jones, J. M, M. A. Maloney, and J. C. Giibreath, 1964. Size, shape and color pattern as criteria for identifying Coturnix eggs. Poultry Sci. 43: 1292-1294. Kiker, J. T., and P. B. Siegel, 1972. Fecundity of Coturnix coturnix japonica as influenced by daily mating regimes. Page 205 in: Proceedings of Southern Agricultural Workers Inc., 69th Annual Convention, Richmond, VA. Marks, H. L., 1971. Selection for four-week body weight in Japanese Quail under two nutritional environments. Poultry Sci. 50:931-937. Marks, H. L., 1978. Long term selection for four-week body weight in Japanese quail under different nutritional environments. Theor. Appl. Genet. 52: 105-111. Marks, H. L., and P. D. Lepore, 1965. A procedure for artificial insemination of Japanese Quail. Poultry Sci. 44:1001-1003. Marks, H. L., and P. D. Lepore, 1968. Growth rate inheritance in Japanese Quail. 2. Early responses to selection under different nutritional environments. Poultry Sci. 47:1540-1546. Woodard, A. E., and H. Abplanalp, 1967. The effects of mating ratio and age on fertility and hatchability in the Japanese quail. Poultry Sci. 46:383-388.
Downloaded from http://ps.oxfordjournals.org/ at Rutgers University Libraries/Technical Services on June 5, 2015
affected by the switching, whereas others obviously had lower fertilization rates when switched (Table 1). Stress caused by this switching may have been responsible for the decrease in fertilization of eggs for some males (Camci, 1989). Kiker and Siegel (1972) also suggested that social interactions between sexes during allocated mating times may result in different stress levels. It is presumed that the treatment affected mating activity. The identity of the male did not influence egg production of the female. Females that were only mated every 4th day, however, laid fewer eggs than permanently paired females in the second experiment. It is not clear whether this decrease in egg production was also caused by stress or by the absence of a male during 75% of the time. Mean hatchabilities of eggs from the switched males treatment were similar in Experiments 1 and 2. These data indicate that by collecting eggs over a 21-day period it is possible to obtain full-sib families of 12 to 14 individuals. Families of this size should be adequate for half-sib breeding designs to estimate heritabilities in Japanese quail.