Carcase conformation and leanness of second cross lambs from sires in a central progeny test

Abstract

Proc. Aust. Soc. Anim. Prod. 1996 Vol. 21 CARCASE CONFORMATION AND LEANNESS OF SECOND CROSS LAMBS FROM SIRES IN A CENTRAL PROGENY TEST G.M. GAUNT, P.A. KENNEY and B. WARREN Institute for Integrated Agricultural Development, RMB 1145, Rutherglen, Vic. 3685 Overseas work has identified that Texels provide lean, meaty and heavy lamb carcases (Clarke et al. 1988). They have recently been imported for use as terminal sires in the Australian prime lamb industry for the purpose of satisfying consumer demand for lean, meaty lamb (Hopkins et al. 1986). This paper compares conformation and leanness of second cross lambs sired by selected rams from various breeds used by the prime lamb industry in Australia. Particular focus is on Texels, given the limited information available on the performance of this breed under Australian conditions. Data from the Central Progeny Test (Banks et al. 1995) conducted in 1994 at Rutherglen Research Institute were used to compare 13 Poll Dorset sires with 14 sires representing 12 breeds (Table 1). Since individual sires were selected by studmasters as being superior within their stud, generally on the basis of LAMBPLAN figures, they represent some of the elite genetics available within the national flock for that breed. Each sire was mated to 34 Border Leicester x Merino dams. The resultant progeny (585) grazed together until weaning, after which the ewes and cryptorchids were separated and slaughtered when they reached a mean liveweight of 40 kg and 50 kg respectively. Following slaughter, GR tissue depth was measured and conformation subjectively assessed by an experienced carcase assessor. For analysis, GR tissue depth was adjusted to constant carcase weight of 20 kg. A conformation score of 1 - 7 (1 = poor, 7 = good) was given for each lamb using the following criteria: a) hindleg/chump: muscling, length and width and butt shape b) loin: width and fullness and c) forequarter: width and flatness across blades, muscling and rib shape. There was no interaction between sire and sex. Table 1. Conformation (1 = poor, 7 = good) and GR tissue depth (mm) for different sire breeds . which of the Texels which had lower means for leanness and higher or equal means for conformation. Whilst wider investigation overall potential of Texel genetics for prime lamb production is needed, the current results indicate have the potential to improve the genetics of the Australian prime lamb industry for carcase attributes satisfy current market requirements. BANKS, R.G., SHANDS, C., STAFFORD, J.P. and KENNEY, P. (1995). Central Progeny Testing Results: 199 1, 1992, 1993 & 1994 Matings. Meat Research Corporation. CLARKE, J.N., PARRATT, A.C., MALTHUS, I.C., AMYES, NC., ULJEE, A.E. and WOODS, E.G. (1988). Proc. N.Z. Sot. Anim. Prod. 48: 53-6. HOPKINS, A.F. and CONGRAM, I.D. (1986). Proc. Aust. Sot. Anim. Prod. 16: 239-42. 364