Feedlot Performance and Carcass Compositions of Ghezel and Mehraban Lambs and Their Reciprocal Crosses

The effect of crossbreeding between Ghezel and Mehraban on growth performance and carcass characteristics was studied for two consecutive years using 162 purebred and crossbred lambs. The four groups of lambs involved in the study were purebred Mehraban (MM), purebred Ghezel (GG), crossbred Ghezel ram×Mehraban ewe (GM) and crossbred Mehraban ram×Ghezel ewe (MG). The lambs were fed with grazing of cereal (wheat and barely) pasture, alfalfa as well as with concentrate for 84 days. The results indicated that crossbreeding had significant (p<0.01) effect on average daily gain, chilled dressing percentage and some carcass cuts. Least square means comparisons showed that average daily gain was highest for GM (256.5 g/day) while the lowest for MM (222.0 g/day) lambs. There were no significant differences among among groups for fat-tail weight, and fat-tail percentage. Total dissected internal fat (renal, cardiac, intestine and cavity) was lowest for MM as compared with other groups, but there were no significant differences when total dissected fat corrected for carcass weight. Breed (p<0.05) and initial weight of lambs (p<0.01) had significant effect on leg weight. No significant differences were observed among genotypes for leg percentage, shoulder weight and percentage. The effect of genotype was significant on eye muscle area with purebred Mehraban and MG lambs ranking the lowest and the highest, respectively. There were no significant differences observed for dry matter, crude protein and ether extracts of carcass among groups. The interaction of genotype×year was not significant for any of the traits.