Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/1999
Publication Date: 1/17/2000
Citation: GADES, N.M., BROWN, M.A., NUTTING, D.F., JACKSON, W.G., TOLLEY, E.A. GENOTYPE X ENVIRONMENTAL INTERACTIONS IN SERUM CHOLESTEROL LEVELS OF YOUNG CATTLE. JOURNAL OF ANIMAL SCIENCE. 2000. v. 78(Suppl.2): Abstract p. 4. Interpretive Summary: Abstract Only.
Technical Abstract: Cattle grazing endophyte-infected tall fescue (E+) appear to have a higher prevalence of fat necrosis compared to cattle grazing other forages. Thus, factors in E+ may be associated with changes in lipid metabolism as reflected in altered levels of total serum cholesterol. Also, genotypes and physiologic state of animal, as well as the vegetative stage of the plants may influence any such effects. This study was part of a long-term investigation to characterize the blood cholesterol levels of genotypically different heifers chronically grazing E+ pastures with those grazing bermudagrass (BG) pastures. The study compared blood cholesterol levels in 245 Angus (AA), Brahman (BB), and reciprocal-cross (AB and BA) heifers. Blood samples were obtained at frequent intervals from weaning through their second-calf production stage. Total serum cholesterol was assayed and data were used to evaluate the main effects and interactions of forage environment, genotype, and time on serum cholesterol. Generally, blood cholesterol levels of AB, BA, and BB heifers paralleled each other over time. Grazing either E+ or BG pastures AA heifers had lower blood cholesterol levels compared to the other genotypes (all p < 0.0001). Factors associated with E+ lowered blood cholesterol levels in AA heifers compared with factors associated with BG (p < 0.0003). Mechanisms for these effects remain to be determined. However, at each sampling time, weight gain and loss over the previous period were positively associated with levels of serum cholesterol (p < 0.0001) regardless of genotype.