FEEDLOT AND CARCASS TRAITS OF STEERS OF THE HIGHLAND AND HEREFORD BREEDS AND THEIR RECIPROCAL CROSSES

Abstract

Calves of the Hereford breed, and the Highland × Hereford and Hereford × Highland crosses surpassed those of the Highland in final feedlot weight, average daily gain in the feedlot, cold carcass weight, and dressing percentage. The fat thickness over the eye muscle was significantly less in the Highland than in the other groups; however, when considered as thickness of fat per 100 kg of cold carcass no important breed differences existed. Although area of eye muscle did not differ between any of the breeds and crosses, the Highland had greater area of eye muscle per 100 kg of cold carcass. Calves were slaughtered when the majority of the Herefords were judged, visually, to have reached "choice" or "good" grades. The percentage of animals achieving grades of choice or good was less for the Highland than for the other three groups. Heterosis effects were 6.3, 5.7, 7.1, 1.2, and 5.2% for final feedlot weight, feedlot average daily gain, cold carcass weight, dressing percent, and intramuscular fat. Although the percent heterosis for area of eye muscle and fat thickness over the eye muscle was 4.4 and 5.8, the advantage was in favor of the straightbreds over the reciprocal crosses (5.3%) when considered in terms of area of eye muscle per 100 kg of cold carcass weight. The two crossbred groups were similar to the Hereford, while the Highland was inferior to all three groups in overall performance for the traits in this study.