Effects Of Supplementing Cellulase On Production Performance Of Lactating Dairy Cows In Summer And On In Vitro Rumen Fermentation

The effects of supplementing cellulases on production performance of lactating dairy cows in the summer and on in vitro rumen fermentation were studied to further provide experiment evidence on cellulase utilization in dairy cow production and its possible mechanisms.Exp1. Effects of cellulase on milk production and milk quality in dairy cow in the summer. 50 Chinese Holstein dairy cows with body condition, milk production and lactation approximately accordant were randomly divided into five groups (with 10 cows in each group). The concentrates of group 1 and group 2 were added into mixed-cellulase at level of 50g/t and 100g/t, respectively, and the concentrates of group 3 and group 4 at level of 80g/t and 100g/t, respectively. The time from July 15 to September 15 .The results showed that milk production of cows in groups of 1, 2,3 and 4 increased by 5.73%(P<0.05), 4.84%(P<0.05), 3.62% and 0.51% compared with that of control group.Exp 2. Effects of supplemental cellulases on in vitro rumen fermentation. Rummen fliud inoculum was collected from three rumen-fistulated Holstein bulls. Compound or single cellulases (CC or SC, mg) /substrate(S, kg) were 66.7, 200 and 100 respectively. The time of incubation was 96h. Gas production, pH, DM degradation, NH3-N concentration, total VFA,acetate,propionate and butyrate production were drtermined. The results showed that the 96h cumulative gas production was the highest and increased by 23.7%(P<0.05)compared with the control group when CC/S was 100. There was no diffenrce between group of 66.7mg/kg and the control. The pH in group of 100mg/kg was lower 0.2 than the control group, and other groups had no difference with the control group. The 96h DM degradation in groups of 100mg/kg and 200mg/kg increased by 7.57% and 5.6% compared with the control(P<0.05). The concentration of NH3-N decreased gradually from 0h to 24h and reached the lowest at 24h, and then gradually increased from 24h to 96h. The concentration of NH3-N from 12h to 96h was the highest for group of 100mg/kg ( 4.3 mg/100ml more than the contol). The concentrations of acetate and TVFA were the highest for group of 100mg/kg and higher 7.62 and 9.16 mmol/L than that of the control group, respectively.The present study indicated that milk production of lactating cows could be enhanced in the summer by supllementation of cellulases, but the intake and fat content in milk were not affected. The effect was retalted with the kind of celluase and adding level. In the whole, the effect of compound cellulases was better than that of single cellulases, and the level of 50g/t was more effective for compound cellulases.