Characterization of Ram and Ewe Breeds. II. Growth and Carcass Traits2

Abstract

Rambouillet, Suffolk and Suffolk × Rambouillet rams were mated to Louisiana Native, Hampshire × Native, Rambouillet × Native and Suffolk × Native ewes. When purebred Rambouillet and Suffolk sires were compared to Suffolk × Rambouillet sires, significant differences in favor of purebred-sired lambs were observed for birth weight, feedlot daily gain, lifetime weight per day of age and slaughter weight, but no differences were found for any carcass trait measured. Because of the small sire sample and because the crossbred rams were from a different flock than the Suffolk rams, limited credence should be placed on the slower growth of the crossbred-sired lambs. However, Suffolk-sired lambs were superior to the Rambouillet-sired lambs for most growth and carcass characteristics. Suffolk-sired lambs were significantly heavier at birth, gained more rapidly in the feedlot, had higher lifetime weights per day of age, lower yield grades, less fat thickness over the longissimus muscle, smaller kidney fat weights and heavier weights of retail cuts than lambs from Rambouillet sires. Lambs from Native ewes tended to be smaller at birth, grew more slowly, had smaller longissimus muscle areas and had more kidney fat than lambs from Hampshire × Native, Rambouillet × Native and Suffolk × Native ewes, showing that growth and carcass traits of the Native sheep can be improved by crossing with wool and mutton breeds. Lambs from Suffolk and Hampshire cross ewes excelled those from Rambouillet cross ewes for weaning weight and lifetime weight per day of age. Suffolk and Hampshire cross ewes also produced lambs with larger longissimus muscle areas, less kidney fat and lower yield grades than lambs from Rambouillet cross ewes. In addition, lambs from Hampshire × Native ewes were fatter and lower in cutability than lambs from Suffolk × Native ewes.