Characterization of Biological Types of Cattle II. Postweaning Growth and Feed Efficiency of Steers

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Abstract
Postweaning growth and feed efficiency of 1,105 steers from matings of Hereford and Angus dams to Hereford, Angus, Jersey, South Devon, Limousin, Charolais and Simmental sires were analyzed. Differences were large for 405-day weight (range of breed group means = 14%), average daily gain (ADG) (range = 19%) and relative growth rate (RGR) (range = 10%). Charolais and Simmental crosses, followed by South Devon crosses, were the largest, fastest gaining breed groups; Hereford-Angus cross-breds and Limousin crosses were similar in ADG and 405-day weight; and Jersey crosses were the smallest, slowest growing. South Devon and Simmental crosses had the highest RGR, whereas Limousin and Jersey crosses had the lowest. Breed group rankings were similar for ADG and RGR. Feed efficiency was evaluated over age (0 to 217 days on feed) and weight (240 to 470 kg) intervals and to a longissimus fat-constant end point (0 days to 5% longissimus fat) by regression analysis of data for breed groups fed in replicated pens and slaughtered serially at three dates within each year. Breed group differences were large for weight-constant (range = 23%), but reduced for age-constant (range = 9%) and longissimus fat-constant (range = 12%) intervals. ADG from 240 to 470 kg tended to explain relative ranking of breed groups for weight-constant efficiency. When tested against a significant breed-group by year interaction, Jersey crosses were less efficient than Charolais crosses in the age-constant interval. When evaluated to 5% longissimus fat, Limousin crosses were least efficient, but not different (P>.05) from Simmental crosses. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.