Evaluation of the growth performance and carcass characteristics of lambs produced in Quebec

Data for a total of approximately 1100 lambs tested in 12 trials from 1992 to 1995 in commercial lamb test stations in Quebec were used to determine the effect of sex, sire breed and genetic type on growth performance and carcass characteristics. Lambs were housed two to a pen and fed commercial diets. Maximum test length was 112 d. Lambs were slaughtered when their liveweight was approximately 47 +/- 5 kg for the males and 43 +/- 4 kg for the females. Feed intake and growth rate were measured during the test, and carcass measurements were taken at slaughter and at 24 h following slaughter. Feed intake was the average for the pen, while the growth and carcass measurements were taken individually. Males ate more per day, had better gain and were younger at slaughter than females. Females had more body fat and better carcass conformation scores than males. However, males did not have a greater loin muscle thickness compared to females. Lambs sired by Hampshire or Suffolk rams had superior growth performance and leaner carcasses than lambs sired by Dorset rams. However, Hampshire and Suffolk-sired lambs did not have a greater loin muscle thickness compared to Dorset-sired lambs. Analysis of different genetic types did not demonstrate a pronounced effect on lamb performance. No specific genetic composition was clearly superior to the others for the various variables studied. Genetic quality within a breed of sheep bought or kept for reproduction is as important as the choice of breed or the combination of breeds.