Two growth trials were designed to measure the effects of: (1) dietary Virginiamycin (0 or 16.5 mg/kg) and added fat (0 or 4%), and (2) Virginiamycin (0 or 16.5 mg/kg) and dietary lysine levels (low, NRC, high) individually, and in combination on broiler performance. A third trial investigated the relationship of plasma glucose, triglyceride and phospholipid concentrations with degree of fatness/leanness in genetically lean and fat broiler chickens. A combination of supplemental fat and Virginiamycin increased protein and decreased fat content of the dressed carcass. Virginiamycin supplementation overcame the growth depression of a low lysine diet by increasing feed intake. In the low lysine diet, Virginiamycin supplementation reduced abdominal fat deposition in females and increased carcass yield in males. Carcass protein content was increased by feeding the NRC-recommended level of lysine or by Virginiamycin supplementation. (Abstract shortened by UMI.)

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The effects of dietary fat on the reproductive performance of broiler breeder chickens have been studied. Individually caged broiler breeders were fed diets with or without added fat during 19-wk reproductive period. In Experiment 1, only the females were subjected to dietary treatments: control (no added fat), 3% animal-vegetable fat blend (A-V fat, 3% corn oil (CO)), while the males received a non-added fat diet. In Experiment 2, only the males were fed diets containing 0 or 3% of either A-V fat or CO while the females were provided a non-added-fat diet. / In Experiment 1, added dietary fat produced significantly higher fertility and early embryonic livability. In Experiment 2, inclusion of 3% CO in the males' diets significantly increased late embryo livability and total embryo survival resulting in a significantly higher hatchability. There were no differences in semen characteristics among dietary treatments. These data indicate that the contribution of the male is not restricted to the fertilization of eggs but is also related to embryonic livability. The addition of fat significantly affected the fatty acid composition of the phospholipid fraction of the spermatozoa cells.

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