Effects Of Fibrolytic Enzymes, Isobutyrate Or Their Combination On Development Of Small Intestine In Dairy Calves

To study the effects of dietary supplement with fibrolytic enzymes, isobutyrate or their combination on development of small intestine in pre-weaning and post-weaning dairy calves. Thirty Chinese Hostein bull Calves about30day after birth with similar birth weight were chosen and divide into four groups and supplemented with four concentrations:Control (without additives), FE, IB and IBFE with1.83g fibrolytic enzymes (contained160units of cellulase according to filter paper activity and4000units of xylanase),6.0g isobutyrate and their combination per calf per day, respectively.The calves were slaughtered on45d,60d and90d after birth. Determination of the length of the small intestine and loin eye area, collecting various bowel intestinal contents, intestinal mucosa, liver, blood and muscle samples for the determination of intestinal tissue morphology, activity, gene expression and muscle composition. The results showed that the small intestine wall thickness, mucosal thickness, villus length and crypt depth were increased companied with the growth of calves (P<0.05). All items of small intestine in groups supplemented IB and IBFE were higher than that of in group supplemented FE and control group significantly (P<0.05), while no significant differences were found between groups supplemented IB and IBFE (P>0.05). IBFE was significantly higher than the other groups (P<0.05) in maltose activity, amylase activity, trypsin activity and lipase activity. The scanning electron microscopy results showed the growth of small intestine were increased with the growth of calves. The villus of small intestine in group supplemented IBFE group were superior to control group. The expression of function gene were compared by determining the mRNA abundances of GHR, INSR, SGLT1in different parts of small intestine with quantitative real-time PCR. The expression of GHR, INSR and SGLT1were increased with the growth of calves in digestive system. The expression of GHR in groups supplemented IB and IBFE were higher than that of in group supplemented FE group and control group significantly (P<0.05), while no significant differences were found between groups supplemented IB and IBFE (P>0.05). The expression of INSR of small intestine in group supplemented IBFE was superior to control group and groups supplemented FE and IB. The expression of SGLT1in groups supplemented IB and IBFE were higher than that of in group supplemented FE significantly (P<0.05). IBFE for meat fat, protein and loin eye area were significantly better than the control group (P<0.05). IB and IBFE liver IGF-1mRNA expression was significantly higher than the other two groups (P<0.05), but the difference between the two groups was not significant. IBFE liver INSR mRNA expression was significantly higher than other groups. IB and IBFE in the serum glucose concentrations, albumin, total protein concentration, total cholesterol, triglyceride concentration, urea nitrogen, enzyme aspartate, alanine activity, LDH activity, APK vitality, Growth hormone concentrations, insulin and IGF-1concentrations were significantly higher than the control group and FE (P<0.05). These results indicated that the optimum dose of IBFE.