The Effect of Selection on Egg Production in Single Comb White Leghorn Fowl

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Munday, Reuben Abraham
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The practical value of any system of breeding for egg production must be demonstrated first to be appreciated by the average poultryman. High egg yield has been found by several workers to be due to the combined influences of early sexual maturity, non-winter pause, high intensity, non-broodiness and high persistency. Goodale and MaeMullen (11), Hays (24) and goodale and sanborn (13) suggest that these five traits are inherited in a Mendelian manner. It would seem to be desirable to develop a breeding system which will combine the above named characteristics in individual birds in order to obtain the maximum egg yield. The difficulty of combining these traits has been indicated by the work of Pearls (48), Dryden (4) and Jull (33). Pearl concluded that all hens were not able to transmit equally their egg production was confirmed by Dryden, who suggested that some hens tranamit their phenotypic egg laying ability to their progeny and others do not. Widely different breeding systems are employed with some success by poultrymen who are interested in development high producing strains of domestic fowl. however, in many cases the rate of progress is generally slow and discouraging to the average poultryman. In general, breeding flooks are selected on the basis of the performance of their ancestors, pullet year records, progeny test, type and constitutional vigor. Jull (33) found that there was no correlation between the first year's egg record of a hen and the egg laying ability f jer daughters. He also included that a hen's pullet year record is not always a good indication of the breeding value of her sons. Jull started his experiment with hens that had pullet year records of 200 eggs or over and selected for breeders each year only those that had laid 200 eggs or more during their first year. If Jull had used all hens regardless if the number of eggs laid, his results might have been different. Dunn (5) presented data which show that there was no important in the egg laying ability of pullets sent to the storrs Egg-Laying Contest over a period of 9 years. These pullets were produced by 192 breeders in different parts of the United States. Such finding indicate that the breeding system generally employed by poultrymen are not adequate to increase the egg production of their flooks and that they need more specific investigation.
The cover page reads "A Thesis submitted to the Graduate Faculty for the Degree of Master of Science, Poultry Breeding." Degree granted by Iowa State College, 1935.
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