Carcass and meat composition and eating quality of m. longissimus lumborum (LI) and leg joints were compared in entire male (ram), castrated male (wether) and female (ewe) Dorset Down-cross and Suffolk-cross lambs at about 20 weeks old. Rams grew faster than wethers and ewes particularly in the earlier maturing Suffolk crosses. Carcass weights ranged from 13 to 24 kg and at the mean carcass weight of 17-7 kg ram carcasses yielded larger shoulder joints. Ram carcasses were assessed visually leaner than those from the other sexes with similar conformation scores. Dorset Down carcasses tended to be fatter than Suffolk carcasses and the leanest carcasses were from Suffolk rams. Intramuscular fatness in LI was similar in all sexes. Intramuscular collagen contents were higher in ram LI than in other sexes. There were no differences in protein content, pH or colour of raw or roast LI. In assessments of eating quality of LI by triangle tests, male and female assessors differentiated twin rams and wethers equally. Category scaling showed LI from ewes to be slightly tougher than those from rams and wethers. Consumer evaluation of leg joints did not detect any differences in odour due to sex and ram meat was assessed better than that from wethers or ewes.

No abstract

Three groups (n = 147) of New Zealand mixed breed lambs averaging 170 d of age and 31.7 kg in weight were killed after a diet of pasture to determine whether the total depth of soft tissues over the 12th rib 11 cm from the dorsal midline (GR) could be measured in live lambs with sufficient accuracy to warrant its use as a selection tool for breeding flock replacements. Relationships among live and carcass measurements and carcass chemical composition also were determined. An ultrasonic measurement of GR in the live lambs was a more accurate predictor of carcass GR (r = .87) and percentage carcass fat (r = .80) than was a measurement of GR made with a needle (r = .80 and .67, respectively). Both measurements were sufficiently accurate to permit culling of over-fat lambs from breeding flock replacement prospects. The best single indicator of percentage carcass fat (r = .87) was a shoulder fat measurement, followed closely by carcass GR (r = .85). Both were superior to USDA yield grade for estimating carcass chemical composition in these young, lightweight lambs. These two measurements also were most highly related to percentage carcass protein (r = -.78 and r = -.77, respectively). These results indicate possibilities for improving the method of evaluating the composition of U. S. lamb carcasses.

No abstract

Twenty-eight male fallow deer (Dama dama), 14 entire and 14 castrated (seven each 1-and 2-year-old) were slaughtered and their carcasses jointed. Each joint was separated into venison, trim A (low visible fat, diced pieces), trim B (pieces suitable only for mincing), waste and bone. Castration had a significant and cumulative effect on live and carcass weights. At 1 year of age castrated males were 80 g/kg lighter in live weight; at 2 years this difference had increased to 119 g/kg. The pattern for differences in hot and cold carcass weights was similar, being 66 and 148 g/kg lighter at 1 and 2 years old, respectively.Castration caused small but significant shifts in the proportions of the primal joints, and the proportions of venison, trim A and trim B. Castrated males had smaller neck (9 g/kg) and saddle (10 g/kg) joints, but 18 g/kg larger legs. In the whole carcass they contained 12 g/kg more venison, but correspondingly less trim A and trim B.Older animals had higher proportions of venison and lower proportions of bone. Venison distribution altered with age, but this was mainly a reflexion of changes in joint proportions.The overall effect of castration was to reduce carcass weights (on which producers are paid) and reduce venison production proportionately to 0-97 and 0-88 of that achieved in 1-and 2-year-old entire males respectively. In some market situations castration may be an acceptable method of producing venison outside of the normal peak production, but the reduced production would require higher schedule prices to be economically viable for the producer.

Collagen concentration and solubility were examined in the semimembranosus and biceps femoris muscles of Romney lambs from the Hight line, a line selected for nine generations on the basis of high body weight at 1 year old. Lambs from the Control (CON) and high body weight (HBW) lines were slaughtered at five ages (0, 42, 70, 274, 365 days). In the semimembranosus muscle, there was no evidence of concentration or solubility differences between the lines at any age, but there was a subtle sex by age interaction, possibly because of increased collagen synthesis in males at puberty. In the biceps femoris muscle, collagen concentration was 14% higher in the HBW line, but there was no difference in solubility. The semimembranosus muscle was shear-tested after cooking to give an objective measure of tenderness. Selection line did not affect shear force. With the semimembranosus muscle, collagen solubility was a better predictor of shear force than collagen concentration, confirming previous work on this muscle. Although the biceps femoris muscle was not shear-tested, it is argued that the higher collagen concentration in the HBW line would cause only a minimal decrease in tenderness. The concentration and the solubility of collagen in A92064 the semimembranosus muscle were significant predictors of the same characteristics in the biceps femoris muscle, a finding that could be useful in a breeding programme.

No abstract

No abstract