Effect of dietary protein level on growth, carcass characteristics, serum biochemical index, and meat quality of Hu male lambs

Abstract

Abstract This study investigated the effects of dietary protein levels on growth, carcass characteristics, serum biochemical index, and meat quality of Hu male lambs. Sixty lambs were randomly divided into 5 groups with 12 lambs in each group. The protein levels of the five diets were: 125 g/kg, 132 g/kg, 140 g/kg, 148 g/kg, and 156 g/kg. Fifteen lambs were slaughtered at the end of 70-d feeding experiment. Lambs fed 140 g/kg protein level diet had highest ADG (p = 0.058), and had lowest FCR (p = 0.079). The concentration of blood urea nitrogen (BUN) in 140g/kg protein level group was significantly higher than that in other groups (p = 0.002). The proportion of non-carcass fat ratio (p = 0.007), perirenal fat ratio (p = 0.013), heart (p = 0.023), and the proportion of mesenteric fat ratio (p = 0.074) linearly decreased with the increase of dietary protein level. The concentrations of blood glucose (GLU), triglyceride (TG), high density lipoprotein cholesterol (HDL) in serum linearly decreased, and dietary protein was associated with quadratic decreases in lactic acid (LACT) (p = 0.018). Furthermore, the dietary protein levels had significant effects on amino acid, and fatty acid profiles of the longissimus lumborum (LL) muscle. Particularly the saturated fatty acids (SFAs) (p