Effect Of 2-Hydroxy-4-(Methylthio) Butanoic Acid Isopropyl Ester On Milk Production And Serum Parameters Of Dairy Cows In Diets With Different Protein Levels

This experiment studied the effect of 2-hydroxy-4-(methylthio) Butanoic Acid Isopropyl Ester (HMBi) s on milk production and serum parameters of dairy cows in diets with different CP level.Experiment one:40 Holstein cows were selected according to the principles of similar age, parity, lactation time and milk yield. They were randomly divided into 4 treatments with 10 cows in each treatment. Treatment Ⅰ was fed the diet with 17%CP level, treatment Ⅱ was fed the diet adding HMBi on the basis of treatment Ⅰ, treatment Ⅲ was fed the diet with 16%CP level, treatment IV was fed the diet adding HMBi on the basis of treatment Ⅲ. We studied the effect of HMBi on milk performance of dairy cows in different protein levels. The result found that adding HMBi could improve milk yield. Milk yield increased 2.09kg/d in treatment Ⅱ than treatment Ⅲ, it was significant difference (P<0.05), but had no significant difference between the other treatments (P>0.05). Milk fat, lactose and milk protein increased and MUN decreased in the treatments adding HMBi, but it was not significant difference between treatments. The somatic cell count (SCC) significantly reduced in treatment Ⅱ than that of treatment Ⅰ (P<0.05), adding HMBi in 16% CP level reduced the SCC, but had no significant difference (P>0.05). Supplementing HMBi could improve dry material intake (DMI) and milk feed ratio, but it had no significant difference between treatments (P>0.05).The results indicate that supplementing HMBi could improve the milk yield and milk production performance and reform milk composition.Experiment two:40 Holstein cows were selected according to the principles of similar age, parity, lactation time and milk yield. They were randomly divided into 4 treatments with 10 cows in each treatment. Treatment Ⅰ was fed the diet with 17% CP level, treatment II was fed the diet adding HMBi on the basis of treatment Ⅰ, treatment Ⅲ was fed the diet with 16% CP level, treatment Ⅳ was fed the diet adding HMBi on the basis of treatment III. We studied that effect of HMBi on blood index and hormone of diary cow in ration of different protein level. The result found that TG, GLU, BUN and NEFA had no significant difference between treatments before and after test (P>0.05). Supplementing HMBi could increase serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decrease malondialdehyde (MDA), but had no significant difference between treatments (P>0.05). The serum insulin-like growth factor-1(IGF-I), prolactin (PRL), insulin (INS), leptin(LEP) had no significant difference between treatments(P>0.05. The result indicated that the supplementing HMBi in the diet had no significant difference on the level of IGF-I, PRL, INS and LEP. It tended to improve the level of LEP and PRL.The results indicate that the supplementation of HMBi had no significant difference on blood biochemical parameters, it tended to had an increase the capacity of antioxidant and decrease the level of BUN.