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Plasma Cholesterol Concentration in Unsupplemented Range Cattle^{1, 2,}

University of Arizona, Tucson

Abstract

Data from 2 years' progeny of a herd of registered Hereford cattle were used to estimate mean plasma cholesterol concentration and its variability at mean ages of 235, 340, 600 and 710 days. The total numbers of bull and heifer progeny contributing data at each of these ages were 334, 260, 232 and 195, respectively. Twelve sires were represented. The herd was maintained under semiarid range conditions.

Year of birth, age of dam, weaning age of animal and sire were considered as possible sources of variation in the statistical analysis. Correlations were computed to estimate relationships between plasma cholesterol concentrations inter se and between cholesterol and subsequent performance traits.

Estimated mean concentrations at the four stages of development for the bull and heifer progeny were, respectively: 235-day, 148± 2.9 and 146±3.4; 340-day, 134±4.3 and 124±3.7; 600-day, 122±3.8 and 118±2.5; and 710-day, 120±4.6 and 140±4.6 mg./ 100 ml. Year of birth had highly significant effects for both sexes at 235 and 600 days of age, and no detectable effect in either sex at 340 days of age. It also had a highly significant effect on heifer but no effect on bull progeny concentrations at 710 days of age. Age of dam showed no effect on the cholesterol concentration of either sex at any stage. Linear regression of cholesterol concentration on age of animal was significant only in the bull progeny at 235 days of age. Between-sire variance exceeded within-subclass variance in six of the eight analyses, but significantly so only in the heifer progeny at 235 and 600 days of age. Simple correlations between cholesterol concentrations inter se and between cholesterol concentration and subsequent performance traits tended to be low and not large enough to be useful for predictive purposes.

¹ Arizona Agricultural Experiment Station Technical Paper No. 1036. This study was conducted in cooperation with the U.S.D.A. under Western Regional Project W-1.

² This material was taken from thesis data submitted by the senior author in partial fulfillment of the requirements for a Master of Science Degree, University of Arizona.

³ Present address: U. S. Range Livestock Experiment Station, Miles City, Montana.