Growth and carcass characteristics of three lamb genotypes finished on the same level of feeding

This study investigated the efficiency of growth and the carcass characteristics of 24 Greyface (Border Leicester X Scottish Blackface), 24 Texel (12 purebred and 12 Texel X Texel-Greyface) and 24 Rouge (12 purebred and 12 Rouge X Rouge-Greyface) lambs finished on the same level of feeding. The efficiency of live-weight gain (kg/MJ) was higher in Greyface compared with Texel lambs (P < 0.01). The efficiency of empty body-weight gain (kg/MJ) was higher in Greyface (P < 0.01) and Rouge (P < 0.05) compared with Texel lambs. The efficiency of carcass gains (kg/MJ) tended to be higher in Greyface and Rouge compared with Texel lambs (P = 0.07). The efficiency of non-carcass component gains (kg/MJ) was also higher in Greyface compared with Texel lambs (P < 0.05). Carcass water, protein, lipid and ash gains did not vary significantly between the genotypes, however carcass energy gain tended to be higher in Greyface and Rouge compared with Texel lambs (P = 0.08). The relative proportions of water, protein, lipid and ash in carcass gains did not vary significantly between the genotypes. At the end of the experiment carcass water content was higher in Texel compared with Greyface lambs (P < 0.05) and carcass ash content was lower in Texel compared with Greyface (P < 0.01) and Rouge (P < 0.05) lambs. The concentration of saturated fatty acids was higher in Greyface compared with Rouge lambs (P < 0.001) and higher in Rouge compared with Texel lambs (P < 0.05). Monounsaturated fatty acid concentrations were higher in Rouge compared with Greyface lambs (P < 0.05) and higher in Texel compared with Rouge lambs (P < 0.001). Polyunsaturated fatty acid concentrations were higher in Rouge and Texel compared with Greyface lambs (P < 0.01). The ratio of n-6:n-3 fatty acids was lower in Rouge compared with Greyface lambs (P < 0.05). The efficiency of empty body gain was higher in male compared with female lambs (P < 0.05). Carcass water (P < 0 .01) and protein (P < 0.05) gains were higher in male lambs. At the end of the experiment male carcasses contained a higher content of water (P < 0.05), protein (P < 0.01) and ash (P = 0.07), and a lower lipid (P < 0.05) and energy (P < 0.001) content. Carcass lipids from male lambs contained a higher concentration of polyunsaturated fatty acids (P < 0.001) and tended to contain a lower concentration of saturated fatty acids (P = 0.06).