Application Of2-Hydroxy-4-Methionine Isopropyl On Diet Of Dairy Cow

By adding HMBi to diet of dairy cow and fermentation substrate of rumen in vitro, this study demonstrated that HMBi could act on milk production, blood components and rumen fermentation, which provided the experimental basis for the application of HMBi on dairy cow.Section one:Investigation of the effect of HMBi on the milk production and reproductive performance of dairy cow.30female Chinese-Holsteins(similar in age, parity, number of lactations, expected date of confinement milk and days in milk of last of fetus production) were randomly separated into2groups,15each, kept in the same condition. Feed the treated group with different levels of HMBi as amino acids compensation, according to the diet structure and lactation stage after their parturition.The results show that average milk production of the treated group in various periods was higher than the control group, but the difference was insignificant (P>0.05). The milk fat, lactose and total solid of the milk product of the treated group in various periods were lower than the control group, while there was an improving tendency of milk protein in the treatment but not significant (P>0.05). The milk ketone in the treated group in various periods was lower than the control group and the difference was significant (P<0.05). There was no difference between the treatment and the control on MUN in the treated dairy cows of various periods. The first-cycle conception rate of treated group was8percent higher than the control group, and the times of mating were desirably decreased, In general, the results indicated that the milk production and reproductive performance of dairy cow can be improved by supplement of methionine hydroxyl analogues isopropyl.Section two:Investigation of the effect of HMBi on the serum biochemical parameters of dairy cow.30female Chinese-Holsteins(similar in age, parity, number of lactations, expected date of confinement milk and days in milk of last of fetus production) were randomly separated into2groups,15each, kept in the same condition. Feed the treated group with different levels of HMBi as amino acids compensation, according to the diet structure and lactation stage after their parturition. The blood samples were taken at the40,80,120,200,280days after postpartum, respectively. And blood plasma was further collected for later analysis. The results show that in a variy of blood plasma chosen at the40,80,120,200,280days after postpartum, the total triglyceride (TG), total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) have no difference(P>0.05) between the treatment and control. The MDA in treated group in80d was greatly higher (P<0.05) than control. There were no significant differences in SOD, blood ketone, BUN between treatment and control for various periods(P>0.05). All these demonstrate the trend that the cholesterol metabolism of dairy cow could be improved by supplementing methionine hydroxyl analogues isopropyl.Section three:This study was conducted to investigate the effect of HMBi on rumen fermentation in vitro. The HMBi were added in three different levels of0%,1%and2%(DM). The results showed that the concentration of acetic acid, butyric acid and TVFA in any of treatments were all higher than control (P<0.05) at12h, but there was no difference between the treatments (P>0.05). The differences of the concentration of acetic acid, butyric acid and TVFA between treatments and control were insignificant, but the treatment Ⅰ was higher than treatment Ⅱ and control at24h. The pH of treatment Ⅰ was higher than treatment Ⅱ and control (P<0.05) at12h. The differences of pH between treatments and control were insignificant at24h. The content of lactic acid in the treatments were greater than control (P<0.05) at24h. The GP in treatments were higher than control(P<0.05) at3,6,12h, but there was no significant difference (P>0.05) among the treatments.It was suggested that the rumen fermentation could be enhanced by supplementing methionine hydroxyl analogues isopropyl.