Abstract

Three hundred and twelve lambs (160 ram, 152 ewe) sired by Texel (n = 118), Oxford Down (n = 94) and Suffolk (n = 100) rams and out of Romney ewes were grazed at Poukawa Research Station, Hastings, to evaluate comparative growth characteristics and carcass composition. Lambs were sourced from a range of commercial properties and sires. Representative samples from each breed and sex were slaughtered after 84, 112 and 145 days on trial. Fasted liveweight gain were significantly (P<0.001) higher for Suffolk-cross (107 g/d) and Oxford Down-cross (101 g/d) lambs than for Texel-cross lambs (84 g/d). At a constant hot carcass weight (HCW) of 19.2 kg, Texel-cross lambs had a significantly (P<0.01) lower GR (mean 12.0 mm) than Suffolk-cross (14.1 mm) and Oxford Down-cross (13.3 mm) lambs. Carcasses were boned to a commercial specification which maximised the removal of bone and fat. At a carcass weight (CW) of 19.2 kg Texel-cross lambs had a significantly (P<0.001) higher saleable meat yield (SMY; 647 g/kg CW) than Suffolk-cross (634 g/kg) and Oxford Down-cross (629 g/kg) lambs. Texel-cross and Oxford Down-cross lambs had a higher proportion of the SMY in high value cuts (HVC) than Suffolk-cross lambs. At a CW of 19.2 kg Suffolk-cross lambs (395 g HVC/kg SMY) had a lower yield than Texel-cross (402 g/kg; P<0.001) and Oxford Down-cross (400 g/kg; P<0.05) lambs. There was no breed by sex interaction, but ewe lambs yielded a significantly higher proportion of HVC in their SMY (402 v 396 g/kg for ewe and ram lambs respectively, P<0.001). At a CW of 19.2 kg eye muscle area was significantly higher (P<0.001) for Texel-cross lambs (13.5 cm2) than for Suffolk-cross and Oxford Down- cross (both 12.7 cm2) lambs, with no sex differences.

GJ, Cruickshank, PD Muir, KS MacLean, TM Goodger, and C Hickson

Proceedings of the New Zealand Society of Animal Production, Volume 56, , 201-204, 1996