Effects Of 5,6-dimethylbenzimidazole And Cobalt Supplementation In High-concentrate Diets On Digestion And Metabolism,Rumen Fermentation And Microflora In Sheep

The purpose of this study was to investigate the effect of the addition of two synthetic vitamin B12precursor substances,5,6-diomethylbenzimidazole（5,6-DMB）and cobalt（Co）,on nutrient digestion and metabolism,rumen fermentation and microflora in sheep.Selected 24 healthy Kazakh Rams of around 8months of age,weight（39.23±2.61 kg）,Install a permanent rumen fistula before the trial,Randomized into 4 groups,6 in each group,The control group was fed a basic diet with a coarse ratio of 7:3,Test I,ⅡandⅢgroups added 80 mg/d to the base diet 5,6-DMB and 0.25 mg/kg Co,100 mg/d 5,6-DMB and 0.50mg/kg Co,120 mg/d 5,6-DMB and 0.75 mg/kg Co（added in the form of cobalt chloride）.They were randomly divided into 4 groups,6 in each group,and the control group was fed with sperm.The basal diet with a crude ratio of 7:3 was supplemented with 80 mg/d 5,6-DMB and 0.25 mg/kg Co and 100 mg/d 5,6-DMB in the basal diets of groups I,II and III,respectively,and 0.50 mg/kg Co,120 mg/d 5,6-DMB and0.75 mg/kg Co（added as cobalt chloride）.The trial lasted for 26 days,of which the pre-trial period was14 days and the positive trial period was 12 days.The digestion and metabolism test was carried out 8days before the positive trial period,and the feed,leftovers and excrement and urine of each sheep were collected and recorded every day.The rumen fluid and blood samples were collected at 5 time points at 0h before feeding and 1,3,5,and 7 h after feeding 4 days after the positive trial period.The results showed that:（1）The dry matter intake and daily weight gain of sheep in each experimental group were significantly higher than those in the control group（P<0.01）.（2）The apparent digestibility of nutrients and the retention rates of nitrogen,calcium,phosphorus and energy in sheep in each experimental group were significantly higher than those in the control group（P<0.01）.（3）The p H value of rumen juice in each experimental group was significantly or extremely significantly higher than that in the control group at all time points（P<0.05）.The ammonia nitrogen concentration in rumen liquid was significantly higher than that in the control group at 1-3 h after feeding（P<0.01）;at 5-7 h after feeding,the experimental group II was significantly higher than that in the control group（P<0.01）.P<0.05).The concentration of propionic acid in rumen juice was significantly higher than that of the control group at 1-3 h after feeding（P<0.01）;at 5 h after feeding,the experimental groups were significantly higher than the control group（P<0.05）.The rumen fluid microbial protein content reached the highest at 3 h after feeding,and the test groups I,II and III were extremely significantly higher than the control group（P<0.01）.higher than the control group（P<0.05）.（4）The concentrations of L-lactic acid and D-lactic acid in the rumen showed a gradually decreasing trend;the activities of lactate dehydrogenase and pyruvate kinase showed a downward parabolic trend with the increase of the addition amount,and reached the lowest in test group II;malate dehydrogenase and amber The activity of acid dehydrogenase showed an upward parabolic trend and was the highest in test group II.（5）The content of vitamin B₁₂ in the rumen juice of sheep in each experimental group reached the peak value at 3 hours after feeding,which was significantly higher than that in the control group（P<0.01）.At 5-7 h after feeding,the experimental groups II and III were significantly higher than the control group（P<0.05）.There was no significant effect on the content of vitamin B₁₂ in sheep serum and urine among the groups（P>0.05）.（6）The blood glucose concentrations of sheep in test groups II and III were significantly higher than those in control group and test group I（P<0.05）,and L-lactic acid and urea nitrogen were significantly higher than those in test groups II and III（P<0.05）.（7）The dominant phyla were Firmicutes,Bacteroidetes and Proteobacteria,and the abundance of Proteobacteria in test group II was significantly higher than that in control group（P<0.01）.The predominant genus was Prevotella,and the abundance of Prevotella in test group II was significantly higher than that in control group（P<0.05）.The above test results show that the addition of 5,6-DMB and Co can promote the growth and digestion and metabolism of sheep,regulate the metabolic pathway of propionic acid by increasing the synthesis of vitamin B₁₂,reduce the activity of key enzymes in lactic acid synthesis,and reduce the production of lactic acid,thereby improving the rumen juice.p H,improve rumen fermentation,regulate rumen microflora,and further provide scientific theoretical basis for promoting the growth and development of ruminants.