Effect of sire breed, year, sex and weight on carcass characteristics of lambs

Abstract

Carcass composition of 314 lambs from 300 Corriedale ewes sired by Corriedale, Southdown, Hampshire Down, Suffolk, Texel and East Friesian rams and born in 2 years were evaluated. Wether and female lambs (110–194 days of age) were slaughtered within a body weight range of 20–51 kg. The carcasses were grouped according to commercial weight class, i.e. light (8.0–12.9 kg), medium (13.0–16.9 kg) and heavy (17.0–23.5 kg). Dressing percentage and fat depth over the 12th rib (GR) were recorded. The carcasses were cut to obtain a double hind pistol cut (DHP) and ribs off without flank. The hindhalves were separated into five commercial joints (loin, steak, chump, leg and shank and deboned). Also total saleable meat yield (SMY), separable fat (SF) and bone were recorded. Moisture, ether extract and crude protein were determined in the steak. Year and sex had significant effect on several carcass measures. Effect of sex was significant for dressing percentage, GR, bone, separable fat, SMY:bone and SMY:SF ratios. Effect of carcass weight group was significant for age at slaughter, dressing percentage, GR, DHP, boned cuts, SMY, bone, fat, SMY:bone and SMY:SF ratios. Sire breed had significant influence on age at slaughter, dressing percentage, GR, DHP, boned cuts, SMY, bone, fat, SMY:bone and SMY:SF ratios. Sire breed had an influence of 3.5 units on dressing percentage, carcass weight group of 2.6 units, year 1.9 units and sex 0.47 units. The difference between the highest (East Friesian) and the lowest (Corriedale) value for the proportion of SMY in the double hind pistol was 6.1% (P<0.01). The East Friesian had the highest ratios of SMY:bone (2.06) and SMY:SF (6.22), whereas in Texel these values were 1.99 and 5.52, respectively. The remaining breeds had significantly lower values ranging from 1.87 to 1.93 (SMY:bone ratio) and 4.80 to 5.24 (SMY:SF ratio). In heavy carcasses the percentage of lambs with a GR higher than 15 mm (overfat) were: Southdown 57%, Suffolk 46%, Texel 46%, Corriedale 36%, Hampshire 21% and East Friesian 0%.