| Objective:This experiment was conducted to study the stress problems of weaning calves,such as reduced feed intake and stunted growth,and to determine the optimal ratio of weaned calves by adding compound microecological preparations and mannan-oligosaccharides to the diet to determine the growth performance,nutrient digestibility and serum physicochemical indexes.The effect of the microecological preparation and mannan oligosaccharide on the diversity of calf rumen flora was analyzed.The results of 16 S r DNA microbial sequencing of rumen fluid were used to analyze the effects of microecological preparations and mannan oligosaccharides on rumen flora diversity of calves,provide ideas for promoting the application of prebiotics in weaning calves.Methods:The test was conducted with 50-day-old Holstein female calves,divided into 4groups of 32 calves,which were kept individually.group C control group was fed the basal diet;calves in groups T1,T2 and T3 were supplemented with 3 g mannan-oligosaccharide,3 g mannan-oligosaccharide + 3 g complex micro-ecological preparation and 3 g complex micro-ecological preparation,respectively,for a pre-feeding period of 7 d.The whole test period was 20 d.The feed intake of each calf was recorded daily.The calves were weighed on an empty stomach before the morning feeding on the 1st,10 th and 20 th days,and the average daily gain(ADG)and meat ratio(F/G)were calculated,and body slope length,body height and chest circumference were measured.From 18 to 20 days of the trial,fecal samples were collected from 6 cows in each group for determination of apparent digestibility of nutrients;before morning feeding on d 1,10 and 20 days of the trial,blood samples were collected from calves for testing of blood biochemical indexes,immune indexes and antioxidant indexes;before morning feeding on d 20 days of the trial,3 calves with similar average body weight in each group were selected and rumen fluid was collected with an oral catheter for 16 S r DNA microbial sequencing was performed to analyze the effect of the microecological compound and mannan oligosaccharide on the diversity of rumen microorganisms in weaned calves.Result:(1)At 1-10 d,the average daily gain(ADG)and average dry matter intake(ADMI)of calves in the T2 group were significantly higher than those in the control group(P<0.05);at 20 d,the bust of calves in the T2 group was obviously higher than the control group(P<0.05);the ability of digestion to dry matter(DM)of calves in the T2 group was significantly higher than the control group(P<0.05),and the crude protein(CP)of calves in the T2 and T3 groups was clearly higher than the control group(P<0.05);1-20 d,the fecal score of the calves in the T2 group was significantly lower than that of the control group(P<0.05).(2)At the 20 d,the Ig G content in the serum of calves in the T2 group was obviously higher than the control group and other groups(P<0.05),and the MDA content of calves in the T2 and T3 groups was significantly lower than the control group(P<0.05).(3)At the 20 th day of the test,the shannon index of rumen microorganisms in calves in the T2 group was clearly higher than those in other groups(P<0.05),the PD whole tree index of T2 group was significantly higher than that of control group and T1group(P<0.05),and the chao1 index in the T2 and T3 groups was apparently higher than that of control and T1 groups(P<0.05).the T1,T2 and T3 groups The number of unique OTU was more than control group.the thick-walled phylum was higher in T2 and T3 groups than in C group,and the abundance of the anthropoid phylum was lower in T1,T2 and T3 groups than in the control group.The dominant groups at the genus level in this test were Erysipelotrichaceae＿UCG-002,unclassified genera,Puccinia＿7,and Eurythrinaceae.The results of Lef Se analysis showed that there were13 obviously different microbial communities in the T2 group at the 20 th day of the test,including Bifidobacteriaceae,Actinobacteria,Bifidobacteriales,Pseudoscardovia,Lachnospiraceae＿NK3A20＿group,Family＿XIII,Eubacterium＿nodatum＿group and Oribacterium,Psychrobacter,Solobacterium,Erysipelotrichaceae＿UCG＿006,Lachnospira,and Catenisphaera.Conclusion:Supplementation of 3g of microecological preparation and 3g of mannan-oligosaccharide to calf pre-weaning can increase the number of beneficial bacteria such as bifidobacteria and actinomycetes in the intestinal tract of calves after weaning,enhance the body,immune and antioxidant capacity as well as improve the digestion and absorption capacity of the body and promote growth. |
PDF Full Text Request