Doctoral Dissertations

Date of Award

3-1966

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

J. K. Bletner

Committee Members

O. E. Goff, C. C. Chamberlain, J. O. Mundt, R. L. Tugwell

Abstract

Consumer demands for chickens with deep yellow skin color and for eggs with moderately yellow yolks have been evident for many years. The degree of pigmentation desired varies considerably according to locations throughout the United States and the world. The use of egg yolks with deep yellow color for specialized foods such as noodles has made the production of such eggs an important part of the poultry industry. Pigmentation is often used in consumer appeal as an attempt to halt the decline in per capita egg consumption and to increase the consumption of broilers. There are problems involved in the production of highly pigmented poultry products. With the advent of high energy-low fiber feeds for both broilers and layers, there has been an interest in the reduction of certain high fiber containing ingredients which may be high in xanthophyll, and, in certain geographical areas, an interest in the use of larger amounts of low xanthophyll containing grains. One species of coccidia, Eimeria maxima, while having little effect on mortality in chickens, is especially troublesome due to its depigmenting effect. The main emphasis in the control of coccidiosis with coccidiostats has been against more pathogenic species of Eimeria than against E. maxima. Therefore, depigmentation continues to be a problem in the production of broilers. While the chicken has no known nutritional or physiological requirements for the xanthophyll pigments, nor can it synthesize these pigments within its body, a greater understanding of factors influencing xanthophyll metabolism would be highly beneficial to the poultry industry. The objectives of the research reported herein were; (1) To study the effects of selected feedstuffs and non-nutritive additives upon xanthophyll metabolism, upon skin and shank pigmentation of young chicks, live and dressed broilers and roasters, and deposition and loss of pigmentation of hens during production. (2) To study the effect of feed intake and environmental temperature upon pigmentation and blood xanthophyll levels of chicks. (3) To study the effects of coccidia upon xanthophyll metabolism.

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