Abstract

Forty Border Leicester (BL) and forty-eight Dorset Down (DD) ewe hoggets (7.5mo) that had been farmed together were scanned using a real-time ultrasound machine, at six sites with one muscle depth (B) and five subcutaneous fat depth measurements (R - tissue depth over fifth rib, C - backfat over last rib, GR, L - backfat over last lumbar vertebrae, T - fat over tail) being taken. Comparisons of tissue ratios (individual fat depth divided by B) were used to characterise subcutaneous fat distribution. From these ratios it was found that the DD had 9%, 10% and 6% greater ratios at R, L and T respectively, and 7% lower ratios at C and GR. Breed differences at R, GR and T were significant (P<0.05). It was concluded that true genetic differences in subcutaneous fat distribution existed between the genotypes studied. These findings have implications for carcass classification, for breeding programmes for lean growth, and for comparisons of the fatness of different genotypes.

DI, Gray, GA Lynch, JC Lockhart, WJ Parker, EG Todd, and IM Brookes

Proceedings of the New Zealand Society of Animal Production, Volume 52, , 11-12, 1992