| Studies have found that there are a large number of microorganisms in the colostrum and normal milk of healthy female animals.These microorganisms may be one of the early sources of microbes in the gastrointestinal tract of newborn calves,which are related to the early establishment of the calf intestinal flora and the microbial-induced immunity.However,in order to avoid pathogenic microorganisms in milk from inducing calf diseases,most large-scale domestic pastures pasteurize colostrum and regular milk before feeding them to calves.While pasteurization kills pathogenic bacteria,it also kills probiotics at the same time.Therefore,to explore whether the addition of probiotics to pasteurized milk can restore the function of probiotics to a certain extent,and thus eliminate the adverse effects of pasteurization on the probiotics of bovine milk,this study added the probiotics found in the colostrum to pasteurized normal milk to detect the effects of probiotics on the growth performance and intestines health of calves.Exp.1 Analysis of the flora composition and milk composition of colostrum and the flora composition in rectal feces of Holstein cows.In this experiment,two large-scale commercial pastures(named as NX and NH pasture)with different living environment and diet formulas were selected in Shanxi Province.Twenty Holstein dairy cows with similar weights and good health conditions from each pasture were selected.Colostrum and rectal stool sample were collected within 6 hours after delivery.Using16S r DNA sequencing technology to analyze the microbes of colostrum and rectal stool.The results showed that,at the phylum level,the dominant colostrum bacteria are Proteobacteria(41.91%),Firmicutes(31.93%),Bacteroidetes(18.66%)and Actinobacteria(4.15%),and the fecal dominant bacteria are Firmicutes(48.46%),Bacteroidetes(44.88%),Proteobacteria(2.14%)and Spirochaetae(2.03%).The colostrum and fecal flora of the two pastures are quite different at the phylum and genus level.Compared with the rectal fecal flora,the colostrum flora from the two pastures was more different.A total of 10 core OTUs(Operational classification unit)were detected in all colostrum samples,belonging to Chryseobacterium,Ruminococcaceae＿UCG-005,Anoxybacillus and other genera.In addition,there are Bifidobacterium Lacti,Lactobacillus plantarum,Lactobacillus casei,Lactobacillus gasseri,Lactobacillus salivarius,Bacillus subagiis,Bacteroides fragiylis,Bacteroides fragiylis,Cacteroides fragiylis,and other probiotic strains in colostrum.The lactose content in Colostrum of NX Dairy’s dairy cows was significantly higher than that of NH Dairy(P<0.05),while the urea nitrogen content of NX Dairy was significantly lower than that of NH Dairy(P<0.01).The SCC of NH Dairy tends to be higher than that of NX Dairy(0.05<P<0.10).There were no significant differences in milk protein,milk fat,and total solids of colostrum in the two pastures(P>0.05).In colostrum microorganisms,the lactose content is positively correlated with the abundance of Psychrobacter and Aequorivita,on the contrary,the lactose content is negatively correlated with the abundance of Christensenellaceae＿R.7＿group,and the urea nitrogen content is negatively correlated with the abundance of Staphylococcus.However,there is no significant correlation between SCC and colostrum flora composition(P>0.05).In colostrum and rectal stool samples,Staphylococcus,Anoxybacillus,Acinetobacter and Chryseobacterium have the same positive interaction relationship(P<0.05).To sum up,there are a large number of microorganisms including core strains and probiotics in colostrum of Holstein cows.There are obvious differences in the structure of colostrum flora in different pastures,while the rectal fecal flora is less affected by pastures.There is a big difference between the colostrum flora of Holstein cows and the rectal fecal flora,but there are shared OTUs and the same microflora interaction network between the two.Exp.2 The effect of probiotics addition in pasteurized regular milk on calf growth performance and rectal fecal flora.Experiment 1 comprehensively analyzed the composition of colostrum microorganisms,and found that there were some bacteria species known to have probiotic functions in colostrum.In order to further explore its influence on calves,this experiment added combined probiotics which existing in colostrum to pasteurized normal milk and then feeds them.The feeding experiment period was lasted for 30 days.Thirty healthy newborn Holstein female calves in pairs were selected according to their weight,and were randomly divided into a probiotic group and a control group,each with 15 calves.The calves of the probiotic group and the control group used the same feeding plan.The probiotic group mixed the weighed probiotics into the pasteurized normal milk before each feeding,and the total feeding amount of each calf was 6×10~9CFU/d.The results showed that the body weight of the probiotic group was significantly higher than that of the control group on the 15th day of the test(P<0.05),and the daily gain of the probiotic group had a tendency to be higher than that of the control group on the 0-15th day of the test(0.05<P<0.10).The feed-to-weight ratio of the probiotic group tended to be lower than that of the control group(0.05<P<0.10).There were no significant differences in body weight,daily gain,dry matter intake and feed-to-weight ratio between the two groups at other times(P>0.05).There were no significant differences in calves’body size,body size index,rectal temperature,and fecal score between the two groups in each time period of the experiment(P>0.05).During the whole trial period(d 0～30),the enteritis incidence of calf in the probiotic group tends to be lower than that in the control group(0.05<P<0.10),and the antibiotic usage rate in the probiotic group was significantly lower than that in the control group(P=0.01)),and there was no significant difference in the usage rate of Darco between the two groups(P>0.05).At other times,the diarrhea rate,fever rate and enteritis rate of calves in the probiotic group were lower than those in the control group,but there was no significant difference(P>0.05).The content of isobutyric acid in the probiotic group was significantly lower than that in the control group(P<0.05),while there were no significant differences in other calf rumen fluid fermentation parameters between the two groups(P>0.05).On the 15th day of the experiment,the PD＿whole＿tree index of the calf rectal fecal microorganisms in the probiotic group was significantly higher than that of the control group(P<0.05),while the Simpson index of the probiotic group was significantly lower than that of the control group(P<0.05);Diversity was extremely significantly higher than that of the control group(P<0.01),but there was no significant difference between the two groups at 30 days of age(P>0.05);on the 30th day,there was no significant difference in the fecal microbial alpha and beta diversity index between the two groups(P>0.05).The dominant bacteria phyla in calf rectal stool were Firmicutes,Bacteroidota,Actinobacteriota,Proteobacteria,Fusobacteriota.In addition,compared with the control group,the genetic relationship between the fecal microorganisms of the probiotic group on the fifteenth day and the thirtieth day was quite different.At fifteen days of age,the probiotic group and the control group had significant differences in fecal microbes of Verrucomicrobiota,Subdoligranulum,Collinsella,Prevotella and Streptococcus;the bacteria genus that was different between the two groups at thirty days was Butyricicoccus,and the difference at phylum level was not significant.In summary,there were a large number of bacteria including core strains and probiotics in Holstein cow colostrum,and the different pastures affected the substance composition and microbial composition of colostrum,while the rectal fecal flora is less affected by pastures.To a certain extent,addition of a combination of probiotics to pasteurized normal milk improved the growth performance of calves,optimized the structure of intestinal flora,maintain the diversity of intestinal flora,prevented diarrhea from worsening to enteritis and other diseases,reduced the use of antibiotics in disease treatment.However,the effect of probiotics was gradually weakened as the calves aged. |
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