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Parthenogenesis in Medium White Turkeys Selected for Low and High Semen Ejaculate Volumes1
Parthenogenesis in Medium White Turkeys Selected for Low and High Semen Ejaculate Volumes1 T. F. SAVAGE and J. A. HARPER Department of Poultry Science, Oregon State University, Corvallis, Oregon 97331-3402 (Received for publication June 10, 1985)
INTRODUCTION
MATERIALS AND METHODS
Spontaneous parthenogenetic development in infertile turkey eggs has been described by Olsen and Marsden (1954). Various environmental factors such as hen's age (Olsen, 1967), season of the year (Olsen, 1968), vaccination with live fowl pox virus (Olsen and Poole, 1962), and egg storage temperature (Schom et al, 1982) have been identified as influences of parthenogenesis in turkeys. Genetic factors (Olsen and Marsden, 1968) have also influenced the incidence of turkey parthenogenesis. Olsen (1965) reported that the incidence of parthenogenesis in Beltsville Small White turkeys was responsive to genetic selection. Negative genetic correlations have also been detected between parthenogenesis, egg production, and hatchability of fertile eggs in a strain of Broad Breasted White turkeys (Schom et al, 1982). Savage et al. (1984) reported that Medium White turkeys subjected to nine consecutive generations of bidirectional selection for semen ejaculate volume were characterized by significant changes in unselected reproductive traits. This report summarizes the incidence of parthenogenesis observed in two successive generations of Medium White turkeys selected bidirectionally for semen ejaculate volume.
Two subpopulations of Wrolstad Medium White turkeys were selected for low (Lo) and high (Hi) semen ejaculate volume for ten consecutive generations. For parthenogenetic observations, eggs from virgin hens were obtained following the onset of production and before artificial insemination. Eggs were collected and marked using individual trapnests for the first 7 and 14 days in the 9th and 10th generations of selection, respectively. Prior to incubation, eggs were stored at 14 C and 80% relative humidity. A Robbins Model 17H incubator with automatic turning was used to incubate the eggs for a 10day period. Subsequently, the large end of all the eggs was removed and the contents of the eggs macroscopically examined for embryonic development. Only cellular growth that could be detected macroscopically was classified as parthenogenesis using the categories described by Harada and Buss (1981). Data was analyzed by a two-way analysis of variance (Steel and Torrie, 1980) with prior transformation of the percentages to arcsin values.
1
Oregon Agricultural Experiment Station Technical Paper No. 7563. This research was conducted as part of the Western Regional Research Project W-142.
RESULTS AND DISCUSSION Macroscopic examination for parthenogenetic development in incubated eggs from the Lo and Hi semen producing hens at the onset of egg producton are summarized in Table 1. The semen volume differences between the Hi and Lo lines for the 9th and 10th generations of selection were + .31 and + .30 ml, respectively. During the two consecutive generations, sig-
401
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 17, 2015
ABSTRACT The incidence of parthenogenesis in two lines of Medium White turkeys subjected to bidirectional selection for semen ejaculate volume was examined during the ninth and tenth generations. A significant increase in the incidence of parthenogenesis was observed in both generations of the line selected for low semen volume. The study suggests that selection for low semen volume may result in the stimulation of parthenogenesis as a means of genome survival. (Key words.- parthenogenesis, turkey, selection, semen production) 1986 Poultry Science 65:401-402
SAVAGE AND HARPER
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Harada, K., and E. G. Buss, 1981. The chromosomes of turkey embryos during early stage of parthenogenetic development. Genetics 98:335 — 345. Olsen, M. W., 1965. Twelve year summary of selection for parthenogenesis in Beltsville Small White turkeys. Br. Poult. Sci. 6:1—6. Olsen, M. W., 1967. Age as a factor influencing the level of parthenogenesis in eggs of turkeys. Proc. Soc. Exp. Biol. Med. 124:617-619. Olsen, M. W., 1968. Changes in level of parthenogenetic development in turkey eggs during two testing seasons. Poultry Sci. 47:2015—2016. Olsen, M. W., and S. J. Marsden, 1954. Mortality among turkey embryos in relation to rate of embryonic development. Poultry Sci. 33:1146— 1151. Olsen, M. W., and S. J. Marsden, 1968. Incidence of parthenogenesis in eggs of various strains and varieties of domestic turkeys, Meleagrisgallopavo. Poultry Sci. 47:1030-1032. Olsen, M. W., and H. K. Poole, 1962. Further evidence of a relationship between live fowl pox virus and parthenogenesis in turkey eggs. Proc. Soc. Exp. Biol. Med. 109:944-946. Savage, T. F., J. A. Harper, and E. D. Lassen, 1984. Unselected responses to divergent genetic selection in Medium White (MW) turkeys for semen yield. Poultry Sci. 63 (Suppl. 1):176. Schom, C. B., W. F. Krueger, and R. L. Atkinson, 1982. The relationship of parthenogenetic development in broad breasted white turkey eggs to level of production and environmental factors. Poultry Sci. 61:2143-2148. Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures of Statistics. A Biometrical Approach. McGraw-Hill Book Co., Inc., New York, NY.
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 17, 2015
nificantly higher incidences (P<.05) of embryonic membranes and the total for all categories of parthenogenesis were observed in eggs of the Lo line. Differences between lines and generations for the parthenogenetic categories of blood islands and live embryos were not tested for significance due to the small numbers observed. With bidirectional selection experiments for quantitative traits, changes in unselected characteristics may occur. The results from this study suggest that the incidence of parthenogenesis in the Lo semen line could be an unselected response to genetic selection pressure for decreased semen volume.
INTRODUCTION
MATERIALS AND METHODS
Spontaneous parthenogenetic development in infertile turkey eggs has been described by Olsen and Marsden (1954). Various environmental factors such as hen's age (Olsen, 1967), season of the year (Olsen, 1968), vaccination with live fowl pox virus (Olsen and Poole, 1962), and egg storage temperature (Schom et al, 1982) have been identified as influences of parthenogenesis in turkeys. Genetic factors (Olsen and Marsden, 1968) have also influenced the incidence of turkey parthenogenesis. Olsen (1965) reported that the incidence of parthenogenesis in Beltsville Small White turkeys was responsive to genetic selection. Negative genetic correlations have also been detected between parthenogenesis, egg production, and hatchability of fertile eggs in a strain of Broad Breasted White turkeys (Schom et al, 1982). Savage et al. (1984) reported that Medium White turkeys subjected to nine consecutive generations of bidirectional selection for semen ejaculate volume were characterized by significant changes in unselected reproductive traits. This report summarizes the incidence of parthenogenesis observed in two successive generations of Medium White turkeys selected bidirectionally for semen ejaculate volume.
Two subpopulations of Wrolstad Medium White turkeys were selected for low (Lo) and high (Hi) semen ejaculate volume for ten consecutive generations. For parthenogenetic observations, eggs from virgin hens were obtained following the onset of production and before artificial insemination. Eggs were collected and marked using individual trapnests for the first 7 and 14 days in the 9th and 10th generations of selection, respectively. Prior to incubation, eggs were stored at 14 C and 80% relative humidity. A Robbins Model 17H incubator with automatic turning was used to incubate the eggs for a 10day period. Subsequently, the large end of all the eggs was removed and the contents of the eggs macroscopically examined for embryonic development. Only cellular growth that could be detected macroscopically was classified as parthenogenesis using the categories described by Harada and Buss (1981). Data was analyzed by a two-way analysis of variance (Steel and Torrie, 1980) with prior transformation of the percentages to arcsin values.
1
Oregon Agricultural Experiment Station Technical Paper No. 7563. This research was conducted as part of the Western Regional Research Project W-142.
RESULTS AND DISCUSSION Macroscopic examination for parthenogenetic development in incubated eggs from the Lo and Hi semen producing hens at the onset of egg producton are summarized in Table 1. The semen volume differences between the Hi and Lo lines for the 9th and 10th generations of selection were + .31 and + .30 ml, respectively. During the two consecutive generations, sig-
401
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 17, 2015
ABSTRACT The incidence of parthenogenesis in two lines of Medium White turkeys subjected to bidirectional selection for semen ejaculate volume was examined during the ninth and tenth generations. A significant increase in the incidence of parthenogenesis was observed in both generations of the line selected for low semen volume. The study suggests that selection for low semen volume may result in the stimulation of parthenogenesis as a means of genome survival. (Key words.- parthenogenesis, turkey, selection, semen production) 1986 Poultry Science 65:401-402
SAVAGE AND HARPER
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REFERENCES ^•O ©
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Harada, K., and E. G. Buss, 1981. The chromosomes of turkey embryos during early stage of parthenogenetic development. Genetics 98:335 — 345. Olsen, M. W., 1965. Twelve year summary of selection for parthenogenesis in Beltsville Small White turkeys. Br. Poult. Sci. 6:1—6. Olsen, M. W., 1967. Age as a factor influencing the level of parthenogenesis in eggs of turkeys. Proc. Soc. Exp. Biol. Med. 124:617-619. Olsen, M. W., 1968. Changes in level of parthenogenetic development in turkey eggs during two testing seasons. Poultry Sci. 47:2015—2016. Olsen, M. W., and S. J. Marsden, 1954. Mortality among turkey embryos in relation to rate of embryonic development. Poultry Sci. 33:1146— 1151. Olsen, M. W., and S. J. Marsden, 1968. Incidence of parthenogenesis in eggs of various strains and varieties of domestic turkeys, Meleagrisgallopavo. Poultry Sci. 47:1030-1032. Olsen, M. W., and H. K. Poole, 1962. Further evidence of a relationship between live fowl pox virus and parthenogenesis in turkey eggs. Proc. Soc. Exp. Biol. Med. 109:944-946. Savage, T. F., J. A. Harper, and E. D. Lassen, 1984. Unselected responses to divergent genetic selection in Medium White (MW) turkeys for semen yield. Poultry Sci. 63 (Suppl. 1):176. Schom, C. B., W. F. Krueger, and R. L. Atkinson, 1982. The relationship of parthenogenetic development in broad breasted white turkey eggs to level of production and environmental factors. Poultry Sci. 61:2143-2148. Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures of Statistics. A Biometrical Approach. McGraw-Hill Book Co., Inc., New York, NY.
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 17, 2015
nificantly higher incidences (P<.05) of embryonic membranes and the total for all categories of parthenogenesis were observed in eggs of the Lo line. Differences between lines and generations for the parthenogenetic categories of blood islands and live embryos were not tested for significance due to the small numbers observed. With bidirectional selection experiments for quantitative traits, changes in unselected characteristics may occur. The results from this study suggest that the incidence of parthenogenesis in the Lo semen line could be an unselected response to genetic selection pressure for decreased semen volume.