| This experiment was conducted to investigate the effects of different levels of rumen protected betaine on production performance,digestion and metabolism and slaughter performance of Kazakh lambs.Twenty male Kazakh big-tail sheep aged 3 months were randomly divided into 4 groups: control group(CON),group of 2 g/d rumen protected betaine(L-RPB),group of 4 g/d rumen protected betaine(M-RPB)and group of 8 g/d rumen protected betaine(H-RPB).The pre-feeding period lasted for 10 days,and the normal feeding period lasted for 90 days.The results showed as follows :1)The body weight of experimental groups at 30 d,60 d and 90 d was lower than that of control group,but there was no significant difference between different leves of rumen protected betaine groups(P > 0.05).The body weight gain,average daily feed intake and feed/gain in experimental groups at 0-30,30-60 and 60-90 days were lower than those in control group,but there was not significantly among groups(P > 0.05).2)In terms of apparent digestibility,the gross energy digestibility in 30 days in the M-RPB group was significantly higher than that in the control group(P < 0.05);The crude lipid digestibility of M-RPB group in 60 days was significantly higher than that of H-RPB group(P < 0.05);But other nutrient digestibility were not significantly among all groups in 30,60,90 days(P > 0.05).In terms of retention rate,the fecal calcium excretion in the control group was significantly higher than that in the H-RPB group(P < 0.01)when different doses of rumen protected betaine were added in the condition of calcium metabolism at 30 days.The fecal phosphorus excretion in control group was significantly higher than that in low-dose group(P < 0.01).There were no significant differences in nutrient retention and retention rate among all groups on 60 d and 90 d(P > 0.05).3)Compared with the control group,the abdominal fat weight and abdominal fat percentage in experimental groups were significantly decreased by adding different doses of rumen protected betaine(P <0.05).There were no significant differences in live weight before slaughter,carcass weight,slaughter percentage,carcass length,net meat weight,net meat percentage,lean meat weight,lean meat percentage,fat weight,fat percentage,abdominal fat weight,abdominal fat percentage,sebum fat percentage,skin fat percentage,tail fat weight,tail fat percentage,bone weight,flesh to bone ratio,eye muscle area and GR value among groups(P > 0.05).In conclusion,in this experiment,dietary supplementation of different levels of rumen-passing betaine does not significantly improve the performance,digestion and metabolism of Kazakh lambs,but has a tendency to regulate fat deposition and increase the proportion of lean meat in growing lambs. |
