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The Weight of Chicken Eggs as Influenced by Diallel Crossing
T h e Weight of Chicken Eggs as Influenced by Diallel Crossing NELSON F. WATERS Senior Geneticist, U. S. Regional Poultry Research Laboratory, East Lansing, Michigan (Received for publication June 15, 1944)
Jull (1940) presented a thorough review of the literature on egg weight, together with a list of references of the most important work up to that time. It is evident after a complete review of the literature that there are many complex problems involved in a study of the inheritance of egg weight. Before a critical study of egg weight is made, it is necessary to find some measurement of the male's ability to transmit egg weight. It is assumed that
the best measurement of the egg weight transmissibility of a sire is the progeny test. However, there is no conclusive experimental evidence to show that this is necessarily true. The objective of the present analysis is to determine sire influence as it affects the egg weight of his progeny by means of diallel crossing in which the same dam is mated with two different sires. The material used in the present study consists of 28 sires and 14 dams of the White Leghorn breed. In all, 14 dams were each mated to 2 different sires. Each sire-dam combination produced 5 progeny, or a total of 140 progeny. The use of diallel crossing should equalize the dam influence and permit a measurement of the sire. Inbreeding was presumably not a factor in this analysis inasmuch as the sires used within the different sets were unrelated and only three of the dams had a half-sib relationship. Waters (1937) has demonstrated that maximum adult egg weight is attained when a bird reaches definitive body weight at approximately 10 months of age. The average egg weight of the birds used in this study was obtained after all birds had attained definitive body weight. A sample of eggs from each bird studied was weighed for a period of one week each month for the five months, January to May inclusive. . The average egg weight for each of the 28 different matings is shown in Table 1. An analysis of the 14 sets of progeny shows that a significant correlation of
81
Downloaded from http://ps.oxfordjournals.org/ at University of North Dakota on June 17, 2015
A REPORT by Waters (1941) failed to •*• *• find any measurable influence of the sire on the egg weight of his progeny. The dam's influence on the egg weight of her progeny was pronounced and this author concluded with caution that the inheritance of egg weight was predominantly maternal, inasmuch as there were numerous inconsistencies favoring a strictly maternal influence. Data were also presented to show that significant differences in egg weight between reciprocal Fi hybrids occurred, which suggested sex linkage. Further, certain isolated matings indicated some male influence. A lack of expression of egg weight in the male suggests the need for some method of measuring the transmissibility of this trait. Theoretically the sire's dam, his full sisters, and his progeny should offer the most promising measure of his inherent ability to transmit egg weight. However, these three measurements have failed to give any useful estimate of a sire's ability to transmit or influence the egg weight of his progeny.
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NELSON F. WATERS
TABLE 1.—Average egg weight in grams of the progeny of the same dam when each dam is mated with two different sires Ave. egg weight of progeny Dam
Difference First sire
Second sire
56 53 51 51 52 64 60 55 61 64 57 53 60 53
60 55 52 53 53 64 61 49 54 60 55 53 61 50
mean that the same dam producing two groups of progeny from different sires influences the egg weight of her progeny to such an extent that it cannot be overcome by changing sires. Thus, the data permit the assumption that the progeny within sets were part of a similar sample. Further, these data indicate that egg weight inheritance is predominantly maternal and that any genetic influence of the paternal parent is insignificant. The question might be raised as to whether the two sires mated to the same dams were genetically alike. Such a possibility might prevent genetic differences from being
expressed in the progeny. Considering that all of the males used in this experiment were chosen at random, the probability that such combinations in all instances were selected by chance alone is remote indeed. The results obtained in this study substantiate those obtained by Waters (1941) in which it was shown that egg weight inheritance is predominantly maternal. The mode of inheritance of egg weight is extremely important to the poultry breeder. The use of diallel crossing wherein more than one sire is mated to the same dam, should demonstrate differences in the egg weight of the progeny if such differences exist. The present study has demonstrated that the sire does not influence measurably the egg weight of his progeny. It remains for future research to determine whether these results represent the universal genetic pattern of egg weight inheritance in the chicken. SUMMARY
A study has been made of the influence of the sire on the egg weight of the progeny by means of diallel crossing. The data include 28 sires and 14 dams, wherein each dam was mated to 2 different sires. Each sire-dam combination produced 5 progeny, or a total of 140 progeny. An analysis of the material indicates that egg weight inheritance is predominantly maternal and that any genetic influence of the paternal parent is insignificant. REFERENCES
Jull, Morley A., 1940. Poultry breeding. John Wiley and Sons, Inc., New York. 484 pp. Waters, Nelson F., 1937. Body weight, egg weight, sexual maturity and growth rate in the domestic fowl. Poultry Sci. 18:305-313. Waters, Nelson F., 1941. Genetic aspects of egg weight observed during inbreeding experiments. Poultry Sci. 20:14-27.
Downloaded from http://ps.oxfordjournals.org/ at University of North Dakota on June 17, 2015
.574 exists between the progeny of the same dams when mated to different sires. ' The mean of the total sample is 56.1 (s = 5.2) grams. The mean of X is 56.5 (s= 4.84) grams and the mean of Y is 55.7 (s = 5.2) grams. No significant difference (Fisher's t test) exists between the means of the two groups of progeny from the same dam. An evaluation of the present data indicates that the interdependency of the two sets of variates may be interpreted to
Jull (1940) presented a thorough review of the literature on egg weight, together with a list of references of the most important work up to that time. It is evident after a complete review of the literature that there are many complex problems involved in a study of the inheritance of egg weight. Before a critical study of egg weight is made, it is necessary to find some measurement of the male's ability to transmit egg weight. It is assumed that
the best measurement of the egg weight transmissibility of a sire is the progeny test. However, there is no conclusive experimental evidence to show that this is necessarily true. The objective of the present analysis is to determine sire influence as it affects the egg weight of his progeny by means of diallel crossing in which the same dam is mated with two different sires. The material used in the present study consists of 28 sires and 14 dams of the White Leghorn breed. In all, 14 dams were each mated to 2 different sires. Each sire-dam combination produced 5 progeny, or a total of 140 progeny. The use of diallel crossing should equalize the dam influence and permit a measurement of the sire. Inbreeding was presumably not a factor in this analysis inasmuch as the sires used within the different sets were unrelated and only three of the dams had a half-sib relationship. Waters (1937) has demonstrated that maximum adult egg weight is attained when a bird reaches definitive body weight at approximately 10 months of age. The average egg weight of the birds used in this study was obtained after all birds had attained definitive body weight. A sample of eggs from each bird studied was weighed for a period of one week each month for the five months, January to May inclusive. . The average egg weight for each of the 28 different matings is shown in Table 1. An analysis of the 14 sets of progeny shows that a significant correlation of
81
Downloaded from http://ps.oxfordjournals.org/ at University of North Dakota on June 17, 2015
A REPORT by Waters (1941) failed to •*• *• find any measurable influence of the sire on the egg weight of his progeny. The dam's influence on the egg weight of her progeny was pronounced and this author concluded with caution that the inheritance of egg weight was predominantly maternal, inasmuch as there were numerous inconsistencies favoring a strictly maternal influence. Data were also presented to show that significant differences in egg weight between reciprocal Fi hybrids occurred, which suggested sex linkage. Further, certain isolated matings indicated some male influence. A lack of expression of egg weight in the male suggests the need for some method of measuring the transmissibility of this trait. Theoretically the sire's dam, his full sisters, and his progeny should offer the most promising measure of his inherent ability to transmit egg weight. However, these three measurements have failed to give any useful estimate of a sire's ability to transmit or influence the egg weight of his progeny.
82
NELSON F. WATERS
TABLE 1.—Average egg weight in grams of the progeny of the same dam when each dam is mated with two different sires Ave. egg weight of progeny Dam
Difference First sire
Second sire
56 53 51 51 52 64 60 55 61 64 57 53 60 53
60 55 52 53 53 64 61 49 54 60 55 53 61 50
mean that the same dam producing two groups of progeny from different sires influences the egg weight of her progeny to such an extent that it cannot be overcome by changing sires. Thus, the data permit the assumption that the progeny within sets were part of a similar sample. Further, these data indicate that egg weight inheritance is predominantly maternal and that any genetic influence of the paternal parent is insignificant. The question might be raised as to whether the two sires mated to the same dams were genetically alike. Such a possibility might prevent genetic differences from being
expressed in the progeny. Considering that all of the males used in this experiment were chosen at random, the probability that such combinations in all instances were selected by chance alone is remote indeed. The results obtained in this study substantiate those obtained by Waters (1941) in which it was shown that egg weight inheritance is predominantly maternal. The mode of inheritance of egg weight is extremely important to the poultry breeder. The use of diallel crossing wherein more than one sire is mated to the same dam, should demonstrate differences in the egg weight of the progeny if such differences exist. The present study has demonstrated that the sire does not influence measurably the egg weight of his progeny. It remains for future research to determine whether these results represent the universal genetic pattern of egg weight inheritance in the chicken. SUMMARY
A study has been made of the influence of the sire on the egg weight of the progeny by means of diallel crossing. The data include 28 sires and 14 dams, wherein each dam was mated to 2 different sires. Each sire-dam combination produced 5 progeny, or a total of 140 progeny. An analysis of the material indicates that egg weight inheritance is predominantly maternal and that any genetic influence of the paternal parent is insignificant. REFERENCES
Jull, Morley A., 1940. Poultry breeding. John Wiley and Sons, Inc., New York. 484 pp. Waters, Nelson F., 1937. Body weight, egg weight, sexual maturity and growth rate in the domestic fowl. Poultry Sci. 18:305-313. Waters, Nelson F., 1941. Genetic aspects of egg weight observed during inbreeding experiments. Poultry Sci. 20:14-27.
Downloaded from http://ps.oxfordjournals.org/ at University of North Dakota on June 17, 2015
.574 exists between the progeny of the same dams when mated to different sires. ' The mean of the total sample is 56.1 (s = 5.2) grams. The mean of X is 56.5 (s= 4.84) grams and the mean of Y is 55.7 (s = 5.2) grams. No significant difference (Fisher's t test) exists between the means of the two groups of progeny from the same dam. An evaluation of the present data indicates that the interdependency of the two sets of variates may be interpreted to