Effects Of N-hydroxymethyl-DL-methionine-Ca(N-HMM-Ca) On Ruminal Fermentation And Performance In Chinese-Holstein Cow

Twenty-five high producing Chinese-Holstein cows were arranged randomly in five groups, which were control (basic ration), treatment1 (basic ration+30gDL-Met), treatment2 (basic ration+45gN-HMM-Ca), treatment3 (basic ration+30gDL-Met+50gL-Lys) and treatment 4(basic ration+45gN-HMM-Ca+50gL-Lys), to study the effect of different treatments on the rumen environment, digestibility of diet nutrients, blood plasma parameters, milk production and milk constituents.The results showed that the concentration of ammonia N in the rumen fluid of the treatment2 was lower than that of control, treatment1, and treatment3 (P<0.01), and it was lower (P<0.01) in treatment4 than that of control and treatment3. Total VFA and acetic concentration in the rumen fluid in treatment2 and treatment4 was higher than control (P<0.05), and the butyric acid concentrations of two treatments tended to elevate (P=0.118, P=0.138).Moreover, pH was unaffected by supplemental AA.The digestibility of DM,CP,ADF in treatment2 and treatment4 were higher than that of control and treatment1.Plasma albumin and total protein were higher (P<0.05) in treatment4 and treatment2 than that of other groups,and PUN was the lowest(P<0.05) in treatment2 of five groups. Plasma glucose, TAA and NEFA were not affected by supplemental AA (P>0.05). The milk production was increased by 6.31% and 6.73% respectively in treatment4 and treatment2 (P<0.05). Fat corrected milk(FCM)in treatment4 is higher than that of control and treatment1(P<0.05), which increased by 9.81% and 8.72%, respectively; FCM in treatment3 and treatment2 were higher than that of control(P<0.05).Milk fat percentages in treatment4 and treatment2 were 6.25% and 6.55% greater than control (P<0.05), and milk fat content increased 105.50g/d and 103.89g/d, respectively. Whereas milk protein percentages was not significant(P>0.05) in five groups, milk protein yield in treatment2 and treatment4 elevated 87.94g/d and 86.5g/d, and more 9.27%(P=0.062)and 9.12% than that of control, respectively (P=0.066).Somatic cell counts, solids and solids-not-fat in milk were similar in five groups (P>0.05). It can be concluded that a fraction: N-HMM-Ca survives rumen microbial degradation to provide a rumen-protected form of methionine, at the same time that it enchanced ruminal fermentation and improved microbe synthesis, so milk production and composition of milk were improved.