Comparison of genotype and nutritional effects on body and carcass characteristics of lambs

Abstract

Abstract Body and carcass characteristics were determined for 128 wether and ewe lambs from the mating of Invermay lean and fat Coopworth selection line rams to randomly selected Romney ewes. The lambs were grazed from 5 to 8 months of age on a tussock grassland overs own with either lotus (Lotus pedunculatus Cav.) or clover (Trifolium sp.) at two allowances, 2 kg (low) or 4 kg (high) dry matter per animal per day. When adjusted to mean cold carcass weight, sire genotype was the only treatment to affect carcass chemical composition. The lambs by lean sires had more water and protein and less fat in their carcasses than the lambs by fat sires. The lean lambs were also heavier and had carcass fat depths that were 15 – 33% lower. In comparison, any significant effects of diet and allowance on subcutaneous fat depths or carcass chemical composition were smaller.