Meat quality of cryptorchid lambs grazing either dryland or irrigated perennial pasture with some silage supplementation

Abstract

The meat quality of lambs grazed on perennial pasture (ryegrass Lolium perenne, cocksfoot, Dactylis glomerata and white clover Trifolium repens) was examined in three treatments; group 1 (S) lambs were grazed on dryland pasture for 30 days and then offered a supplement of pasture silage ad libitum until slaughter, 30 days later ( n = 21). Lambs in group 2 (P) were grazed on dryland pasture throughout ( n = 28) and those in group 3 (IP) on irrigated pasture ( n = 28). Lambs in group IP had a significantly ( p < 0.001) heavier pre-slaughter liveweight and hot carcass weight than lambs in the other two groups. There was no significant difference ( p < 0.05) infatscore between groups or in GR when adjusted to a common carcass weight. For cold carcass weight (reduced sample) IP lambs were still significantly heavier than those from group P, but no different to those from group S ( n = 15, 15 and 10, respectively). There was no significant difference between groups for measures of fatness or for m. longissimus thoracis et lumborum (LL) area when adjusted to a common carcass weight of 23.6 kg. There was a significant difference between ( p < 0.001) treatments for pH, group P carcasses having higher pH values for the LL muscle, with no treatment effect on m. semimembranosus (SM) pH. Differences between groups for meat colour values ( L ∗, a ∗, b ∗ ) showed no consistent trend and there was no significant difference ( p > 0.05) between groups in tenderness of the LL and SM muscles as indicated by shear force values. Aroma of the loin meat from pasture-fed lambs (P) was considered significantly ( p < 0.05) stronger than from lambs in groups S and IP ( n = 6, all groups) and the flavour of samples from lambs in group P was significantly ( p < 0.05) stronger than from lambs in group IP. Overall there was no significant ( p < 0.05) difference in acceptability between groups. The results indicate that consumers would be unlikely to detect the differences identified by the panel and that pasture silage will not have an adverse effect on lamb eating quality.