The effect of production system on carcass and meat quality in lambs

Abstract: The aim of this study was to evaluate effects of different production models in Swedish lamb production on live weight gain (LWG), carcass quality and meat quality. The experiment included four typical production models for weaned male lambs in Sweden; indoor feeding (group 1), grazing on cultivated pasture (meadow fescue (Festuca pratensis Huds.), perennial ryegrass (Lolium perenne L.), timothy (Phlenum pretense L.), white clover (Trifolium repens L.) and red clover (Trifolium pretense L.)) with (group 2) or without (group 3) 0.3 kg concentrate supplementation daily per lamb and grazing on semi natural pasture (group 4). Indoor lambs (group 1) were fed grass silage (timothy, red clover and white clover) ad libitum and 0.8 kg concentrate daily per lamb. There were 20 intact male lambs per group. Feed samples of silage, concentrate and pasture was taken continuously in connection to weighing of lambs throughout the experiment. The LWG of the lambs were registered as well as pasture height in the different pasture paddocks throughout the experiment. At slaughter, live weight, carcass weight, dressing percentage, carcass conformation, fatness, and blood samples for lactate analysis were registered. Additionally, pH and temperature decline in muscle (topside) during the first 24 hours after slaughter, were measured. The rearing system had an effect on LWG (P < 0.0001) where indoor lambs having the highest (377 g/day), followed by cultivated pasture + concentrate (287 g/day), cultivated pasture (245 g/day) and semi natural pasture (212 g/day). Furthermore, lambs on semi natural pasture had lower conformation score (P = 0.0024) and fat score (P < 0.0001) than the other groups. When comparing at which temperature pH reached 6.0 (P < 0.0001), group 1 (19.0°C) had a lower temperature at pH 6.0 compared to the other groups; group 2 (32.6°C), group 3 (32.4°C) and group 4 (35.5°C). This relationship was measured by recording the temperature and pH decrease in the carcass during the first 24 hours after slaughter to indicate the tenderness of the muscle. To have a maximized tenderness there are recommendations that the muscle should enter rigor at approximately 15 °C which indicates that meat from group 2, 3 and 4 could be less tender that meat from group 1. No differences between the four groups were found regarding blood lactate at slaughter, muscle-pH and -temperature at 24 hours after slaughter or muscle-pH at six days post slaughter.