Effects Of Sodium Nitrate And Methionine On Rumen Fermentation And Lactation Performance Of Buffalo

Objective:The purpose of this experiment is to study the effects of dietary sodium nitrate and methionine on rumen fermentation parameters,rumen microbial structure,feed digestibility,milk yield and blood biochemical indexes of buffalo,and to provide scientific basis for the application of sodium nitrate and methionine in buffalo breeding.Methods:Test 1: Effects of sodium nitrate and methionine on rumen fermentation parameters,rumen microbial diversity and number of key microorganisms in lactation buffalo.Forty healthy Mora buffaloes with body weight of 640±25kg and milk yield of 7.63±0.19 kg were randomly divided into 4 treatments with 10 buffaloes in each treatment.Additives used in each group were as follows: group A(blank),group B(sodium nitrate 70g/d),group C(methionine 15g/d),and group D(sodium nitrate 70g/d,methionine15g/d).The experiment lasted for 45 days.This test includes two tests,and the specific methods are as follows:On the 45 th day of the experiment,rumen fluid of buffalo was collected on an empty stomach for the determination of rumen fermentation parameters,microbial diversity and number of key microorganisms.Test 2: Effects of sodium nitrate and methionine on dietary apparent digestibility and blood biochemical indices of lactating buffalo.The experimental buffalo feeding program is the same as program 1.Fecal samples were collected on the 40 th,41st and 42 nd day of the experiment for the determination of digestibility of feed.The experimental buffalo vein blood was collected on an empty stomach on the 45 th day for the determination of blood biochemical indexes.Test 3: Lactation performance of sodium nitrate and methionine on lactation buffalo.The experimental buffalo feeding program is the same as program 1.Milk yield of experimental buffalo was recorded from day 1 to day 45 of the experiment.On days 15,22,27 and 34 of the experiment,buffalo milk samples were collected for milk composition analysis and sodium nitrate residue determination.Results:Test 1:(1)Group B buffalo rumen methanogens number increases significantly(P < 0.05).the rumen fungi quantity has no obvious change(P>0.05).rumen free glutamic acid,leucine,lysine,methionine,phenylalanine,threonine,isoleucine,tyrosine,serine,aspartic acid,histidine content and total free amino acid concentration increases significantly(P<0.05).There is no significant change in volatile fatty acids in rumen(P > 0.05).(2)There is no significant changes in the number of rumen fungi and methanogens in group C(P>0.05),no significant changes in the concentration of 20 kinds of free amino acids and total free amino acids in rumen fluid(P>0.05),and the contents of acetic acid,propionic acid and valerate in rumen are significantly decreased in group C(P < 0.05).(3)The number of rumen fungi in group D are significantly decreased(P<0.05),but the number of methanogen in group D is not significantly changed(P>0.05).Rumen bacteria Shannon and Chao1 index are significantly increased(P<0.05).The results of microbial diversity show that the abundance of Bacteroidetes and Prevotella decreased,while the abundance of Proteobacteria and Acinetobacter increased.The concentrations of 20 kinds of free amino acids and total free amino acids in rumen fluid have no significant changes(P>0.05).The concentrations of propionic acid and valeric acid are significantly decreased(P<0.05),and there is no significant differences in the number of bacteria,protozoa,microbial protein,ammonia-nitrogen concentration and p H value among all groups(P>0.05).Test 2:(1)There is no significant differences in the apparent digestibility of crude protein,neutral detergent fiber,acid detergent fiber among all groups(P>0.05)and the apparent digestibility of dry matter in group B was significantly increased(P < 0.05).(2)Correlation analysis results show that there was a significant positive correlation between rumen fungus number and dietary apparent digestibility(P <0.05).(3)There is no significant differences in the contents of glutamic transaminase,glutamic oxalacetic transaminase,methemoglobin and hemoglobin in blood of buffaloes among all groups(P>0.05).Test 3:(1)There is no significant differences in the contents of milk protein,milk fat,lactose,non-fat solids,total solids and sodium nitrate in buffalo milk among all groups(P>0.05).(2)Compare with group B,buffalo milk yield and 3.5% corrected milk yield in group D is increased by 14.83% and 14.47%,respectively,and there is no significant differences among all groups(P>0.05).The feeding amount of buffalo in group C is significantly decreased(P<0.05).Conclusion:15g/d methionine had no significant effect on rumen microbial structure,which improved dietary digestibility of buffaloes.70g/d sodium nitrate increased the number of methanogens and the content of various free amino acids in the rumen.The combined use of 70g/d sodium nitrate and 15g/d methionine decreased the number of rumen fungi and increased the diversity of rumen bacteria.Compared with sodium nitrate,the combined use of sodium nitrate and methionine increased the milk yield by 14.83%.It is recommended that sodium nitrate and methionine be used together.