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Characterization of Cattle of a Five Breed Diallel: II. Measures of Size, Condition and Growth in Heifers

Texas Agricultural Experiment Station, College Station 77843

Abstract

Data were collected on 473 heifers from a five-breed diallel involving Angus, Brahman, Hereford, Holstein and Jersey. Characters analyzed were weight, height at hooks, weight to height ratio and condition score plus daily gains of weight and height between selected ages from 270 to 630 days. Breedtypes were the five straightbreds plus 10 F₁ crosses, reciprocals pooled. Ninety-one heifers were reared in individual pens on complete diets, while 382 were managed on pasture with supplemental feed; the individually-fed heifers received a higher level of nutrition.

The effects of breedtype and management were statistically significant for most characters and the breedtype-management interaction was significant for weight, weight to height ratio and condition score at many of the ages. Heterosis effects were generally larger under the individually-penned management regimen. Estimates of average heterosis (pasture vs pen) were obtained for weight (7 to 9% vs 13 to 14%), height (2 to 3% vs 2 to 4%) and condition score. Results support the suggestion that heterosis observed in traits of younger animals may be partially due to accelerated development potential in crossbreds; higher nutrition apparently provides the requirement for the expression of this potential.

Breedtype ranks for weight and, to a degree, condition score changed across management regimen. Straightbred Brahmans were heavier, relative to the other straightbreds, on pasture than in the pens. Physiological adaptation is suggested as a partial explanation for the breedtype-management interaction; breeds may have specific ranges of adaptation outside of which they are stressed as the straightbred Brahmans were apparently stressed in pens in the study reported.

¹ Present address: Department of Animal Sciences, Purdue University, West Lafayette, IN 47907.