Effect of yeast supplementation and weight at slaughter on growth performance, carcass traits and body composition in Awassi male lambs

Abstract

To study the effects of supplementing Saccharomyces cerevisiae (yeast) and weight at slaughter on growth performance and carcass characteristics, sixteen weaned Awassi male lambs were used (4–4.5 months) and averaged 29.2 kg in weight. The lambs were divided equally into two groups. The first group was considered as a control (C), while the diet in the second group (T) was supplemented with 5 g of yeast/lamb/day, and all lambs were slaughtered from each group at 40 and 45 kg. Results revealed that lambs fed 5 g of yeast/lamb/day in T groups reached their target slaughter weight faster than lambs in C groups (61.13 vs. 72.75 days). The daily gain in weight was numerically higher, and the feed conversion ratio was better in the T groups compared to the control. Moreover, dressing percentages based on live and empty body weight, shrinkage, rib-eye area and fat thickness were not significantly affected by supplementing yeast. It was noticed that lambs slaughtered at 45 kg had a substantially (P<0.05) larger rib-eye area and a higher percentage of subcutaneous fat and dressing based on live and empty body weight than lambs slaughtered at 40 kg. Lean and fat content were numerically higher in the rack cuts in lambs fed yeast than in the control. However, lean content decreased and fat increased with increasing slaughter weight from 40 to 45 kg. In addition, neither yeast supplementation nor slaughter weight had a significant effect on non-carcass fats.