The effects of diet, slaughter weight and docking on growth, carcass composition and meat quality of fat-tailed Barbarine lambs. A review

摘要

This review summarises the main factors that influence meat production and quality in fat-tailed Barbarine (FTB) lambs. As a general feature, FTB lamb's growth is moderate, and the average daily gain ranges between 100 and 350 g. The carcass being relatively fatty, carcass fat content varies from 10% to 32%; white fat and rose meat are often dominant in these carcasses. The meat fatty acid profile of this fat-tailed breed is similar to that of thin-tailed ones, with a prevalence of palmitic, stearic and oleic acids. The order of dissected adipose tissues accumulation, estimated by allometry coefficients, is in agreement with observations in thin-tailed sheep. However, tail fat allometry coefficient is closer to kidney fat values rather than to the subcutaneous one. Concerning effects of feed level, growth of FTB lambs fed silage is higher than those fed oat hay. With moderate concentrate supply, FTB lambs' growth is more pronounced on pasture diet than on the feedlot (FL) diet. Furthermore, at similar slaughter weights, carcasses of lambs fed pasture diet have less tail and carcass fat than those from lambs fed FL diet (5% and 18% vs. 9% and 24% for grazing and FL lambs, respectively). No difference in fat colour, fat firmness or cooked meat flavour is observed between carcasses obtained at different slaughtering weight (i.e. from 25 to 35 kg). The tail docking of FTB improved lambs' growth particularly before weaning. Its effect on carcass composition and fat proportion depends on stage of slaughtering and type of fattening diet. For suckled lambs (4 months), the docking resulted in the lower carcass fat weight (and proportion), while for fattened lambs, carcass composition was similar for all types of lambs. Overall, FTB lambs always grow slower than Noire de Thibar lambs. This is particularly pronounced during the fattening phase. Then, for FTB breed, the possibilities to obtain heavy carcasses are at risks of fat accumulation, 22.8% vs. 14.4% for FTB and Noire de Thibar thin-tailed lambs, respectively. However, the main advantage of FTB breed is that adults are well adapted to food scarcity and may produce lambs even under harsh conditions.