Date of Award

Winter 1980

Project Type

Dissertation

Program or Major

Genetics (Animal Sciences)

Degree Name

Doctor of Philosophy

Abstract

The major objective of this research was to investigate the relative contribution of genetics, nutritional restriction and the genetics by nutritional restriction interaction upon Rous sarcoma virus (RSV)-induced tumor development in chickens. Two genetic systems were used. The first involved an inbred line and a noninbred line of chickens. The second utilized F2 generation progeny from a cross of lines 6-1 and 15-1, highly inbred lines of White Leghorns from the Regional Poultry Research Laboratory of the United States Department of Agriculture at East Lansing, Michigan. These chickens had been blood typed for allcantigens coded for by genes of the major histocompatibility complex and were of two geneotypes--B2B2 and B5B5. Four-week-old chickens were either full-fed or restricted to 60% of the feed consumed by full-fed chickens of the same age. Two weeks after being placed on experimental rations, chickens were inoculated with RSV-1. Tumors were scored subjectively for size several times during a 10 week period.

Forty percent nutritional restriction delayed the appearance of tumor and reduced tumor size at 2 and 3 weeks post-inoculation (PI). B genotype profoundly influenced tumor size. E2B2 chickens had smaller tumors between 3 and 10 weeks PI than did corresponding B5B5 chickens. Similar to 40% restriction, 50% restriction delayed tumor formation and retarded early tumor growth.

Nutritional restriction may be retarding initial tumor growth by two possible mechanisms: (1)nutritional deprivation may inhibit antibody production, including blocking antibody, and enhance cell-mediated immunity, resulting in inhibited tumor growth, or (2)rapid tumor growth is restricted due to a limited supply of nutrients to the cancer cells. Forty percent restriction did not exert an effect on immunocompetence based upon antibody production to sheep erythrocytes and phytohemaglutinin-stimulated lymphocyte blastogenesis as measures of cell-mediated and humoral immunity, respectively. Thus a limited supply of nutrients may retard initial tumor growth.

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