Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2004
Publication Date: November 1, 2004
Citation: Freking, B.A., Leymaster, K.A. 2004. Evaluation of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds of sheep: IV. Survival, growth, and carcass traits of F1 lambs. Journal of Animal Science. 82:3144-3153. Interpretive Summary: Additive breed effects of Dorset, Finnsheep, Romanov, Texel, and Montadale were estimated for survival, growth, carcass, and composition traits. This study provides comparative information necessary to evaluate potential contributions of these breeds in crossbreeding systems to target specific levels of performance. Differences among these breeds as sires of crossbred progeny were consistent regardless of the ewe breed type. When breed additive effects were estimated independently of maternal effects, Romanov and Finnsheep progeny excelled in fitness traits and were comparable to the other breeds in growth. Breed differences in distribution of carcass fat as well as carcass shape were detected. Romanov and Finnsheep progeny accumulated more kidney-pelvic fat and 12th rib subcutaneous fat. However, predicted carcass lean weight was similar for all sire breeds when compared at a similar carcass weight. This would indicate a different distribution of carcass fat. Under the current USDA yield grading system that classifies lamb carcasses based only on estimated 12th rib fat depth, similar yield grade carcasses out of Finnsheep, Romanov, and Texel sires would be expected to produce 1-1.5 kg less predicted total carcass lean per lamb than Dorset and Montadale sires. Estimated additive breed effects in this study would indicate an increased utilization of the Romanov breed as a maternal contributor to a crossbreeding system can be implemented with minimal consequences in growth or carcass characteristics while increasing reproduction and fitness.
Technical Abstract: Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), and dam breed (Composite III and northwestern whiteface) on survival, growth, carcass, and composition traits of F1 lambs. Effects of mating season (August, October, and December) were estimated for survival and growth traits. Data were collected on 4,320 F1 lambs sired by 102 purebred rams over 3 yr. Birth weight was recorded on all lambs and subsequent body weights were adjusted to 56 (weaning), 70, and 140 d of age (n = 3,713, 3,654, and 3,579 observations, respectively). Survival of dam-reared progeny (n = 4,065) to weaning was recorded. Each yr wethers from October matings were slaughtered in three groups at 25, 29, and 33 wk of age to obtain carcass data (n = 546). In addition to standard carcass traits, resistive impedance measurements were recorded on the warm carcass to predict lean mass. Dam breed (P = 0.37) did not influence lamb survival to weaning but sire breed (P < 0.05) was important. Romanov-sired lambs excelled in survival rate to weaning (94.1%) followed by Finnsheep- (93.0%), Texel- (90.7%), Dorset- (90.0%), and Montadale- (89.1%) sired progeny. Lower (P < 0.01) postweaning growth rate was observed for Texel- (267 g/d) and Finnsheep- (272 g/d) sired progeny than Dorset- (285 g/d), Montadale- (282 g/d), and Romanov- (278 g/d) sired progeny. Sire breed and dam breed were generally significant for most carcass traits. Breed differences in distribution of carcass fat and carcass shape were detected. However, carcass composition was similar for all sire breeds when compared at a constant carcass weight. When evaluated at a constant 12th rib fat depth, carcasses out of Finnsheep, Romanov, and Texel sires produced 1 to 1.5 kg less (P < 0.001) predicted lean mass per lamb than Dorset and Montadale sires. These experimental results provide information about the direct breed effects for survival, growth, and carcass traits of these breeds and their potential use in crossbreeding systems.