DIETARY EFFECTS OF BEEF COMPOSITION .I. QUANTITATIVE AND QUALITATIVE CARCASS TRAITS

Suppressed development of edible portion in carcasses from cattle fed hay during the early feeding period (216-340 kg live weight) was followed by compensatory growth during the intermediate (341-409 kg live weight) and final (410-454 kg live weight) periods. However, when silage in the early feeding period was followed by corn concentrate in the intermediate period, no increased ‘edible portion’ development was achieved beyond that produced by continuous silage. The final feeding period (corn concentrate) resulted in a decline in ‘edible portion’ percentage in cattle that previously received concentrate in the intermediate period whereas those that previously received silage remained at about the same percentage. Cattle fed hay during the early period had less (P < 0.01) carcass weight, less (P < 0.01) fat cover, and more (P < 0.01) reticulo-rumen weight than those fed corn silage for the same period, regardless of slaughter weight. In the heavy (409 and 454 kg) slaughter groups, cattle fed silage in the early period had higher (P < 0.05) marbling scores than those fed hay. Feeding silage in the intermediate period resulted in lower colour (P < 0.01) and firmness (P < 0.01) scores in the longissimus dorsi muscle than feeding concentrate at that time. The dietary regimes used in these studies resulted in widely varying growth rates among treatments with consequential differences in the average age of the animal groups at slaughter. Therefore, the treatment effects observed seem to be easily explicable on the basis of age differences. © 1969, Cambridge University Press. All rights reserved.