Effects Of Rare Earth-chitosan Chelate Salt On Growth Performance 、Nutrients Digestion And Rumen Bacterial Flora Of Buffalo Calves

With the increasing demand for milk and beef,buffalo has been paid more and more attention.The buffalo in China is mainly distributed in Guangxi and Yunnan with high temperature and humidity,and its stress resistance is better than other breeds of cattle.However,there are not many buffaloes in my country,and the commercialization of buffalo products is not mature.Rare earth chitosan chelating salt,as a natural feed additive,has been widely used in all kinds of aquatic fish,poultry and pigs.The results show that most of them can improve the production performance of animals,but there are few reports on their application in ruminant animal feed.This study was conducted to explore the effects of rare earth chitosan chelate on growth performance,economic benefit,blood index,apparent digestibility of nutrients,rumen p H and rumen bacterial flora of buffalo calves.To explore the feasibility of adding rare earth chitosan chelating salt to the diet of buffalo calves,so as to provide theoretical basis for buffalo breeding in Guangxi.In this experiment,18 weaned buffalo bull calves of about 100 days old with good body condition and similar body weight were randomly divided into 3 groups with 6 calves in each group,fed in single column and fed freely.The first group was the control group,which was fed with the basal diet without rare earth chitosan chelating salt,and the other two groups were fed with the diet containing 300 mg/kg and 600 mg/kg rare earth chitosan chelating salt,respectively.The pre-feeding period is 7 days,and the formal test is 60 days.The test results are as follows:(1)the addition of rare earth chitosan chelating salt had no significant effect on the body size growth of buffalo calves,but increased the concentrate and roughage intake of buffalo calves.Compared with the control group,the roughage intake of 600 mg/kg group increased by 16.02%,promoted the rumen development and growth of calves,increased the average daily gain of calves(P<0.05),and significantly increased the economic benefits(P<0.05).The average daily net income of each cow in 300 mg/kg group and 600 mg/kg group was 7.66 yuan and 10.84 yuan more than that in the control group,respectively.(2)under the experimental conditions,the addition of rare earth chitosan chelating salt to the diet could significantly increase the content of albumin in serum of buffalo calves(P<0.05),reduce the contents of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase in serum,and reduce the probability of heart and liver damage.It had no significant effect on other serum biochemical indexes.(3)the addition of rare earth chitosan chelating salt could significantly improve the apparent digestibility of dry matter in buffalo calves.However,there was no significant difference in the effects on GE,CP,NDF and ADF.(4)rare earth chitosan chelate had no significant effect on rumen p H of buffalo calves.At the gate level,Proteobacteria,Firmicutes,Bacteroidetes and Fibrobacteres were the four dominant phyla in the relative abundance of each experimental group,of which the relative abundance of Proteobacterium was 38% ～ 73% and that of Phaeophyta was 17% ～ 41%.The bacteria of Proteus make full use of non-protein nitrogen and improve the utilization rate of nitrogen and crude protein digestion.At genus level,Succinivibrionaceae＿unclassified,Butyrivibrio and Prevotella were the top three dominant genera in relative abundance.The relative abundance of Selenomonas in 300 mg/kg group was significantly lower than that in 600 mg/kg group and control group(P<0.05).Rare earth chitosan chelate significantly decreased the content of Acinetobacter in the rumen of buffalo calves(P<0.05),Reduced the possibility of infection causing disease.At the species level,Butyrivibrio＿unclassified,Prevotella＿ruminicolad,Acidaminococcus＿intestini,Fibrobacter＿succinogenes,Mitsuokella＿unclassifie and Methanobrevibacter＿unclassified were the dominant bacteria in each experimental group.Rare earth chitosan chelate salt could increase the relative abundance of Acidaminococcus＿intestini and reduce the relative abundance of Prevotella＿ruminicola.To sum up,rare earth chitosan chelated salt could promote buffalo calves to eat more roughage and increase average daily gain,and the economic benefits increased by 24.00% and 33.96% respectively compared with the control group.The addition of rare earth chitosan chelating salt had no adverse effect on other aspects of buffalo calves.Generally speaking,the addition of rare earth chitosan chelate salt was beneficial to the growth and development of buffalo calves,and the feeding effect of 600 mg/kg group was better than that of300 mg/kg group.