Effects Of Different Doses Of Molybdenum On The Partial Microbial Population In Rumen And Fermentation Parameters

Objective: To explore the mechanism of ruminant animal molybdenum(Mo) poisoning, the in vitro and in vivo experiment were conducted to investigate the effect of different doses of Mo on rumen fermentation and microbial population.Methods and results: 3 heads of adult Small-tail Han Sheep with similar weight(about 35kg) were fitted with permanent rumen fistula.( 1) Short term artificial rumen fermentation method was used in vitro experiment. Based on the level of Mo in the substrate, there are four groups with 5 replicates of each group. Sample at 0h, 3h, 6h, 9h, 11 h, 22 h and measure the concentration of ammonia nitrogen(NH3-N)、Microbial Protein(MCP) and the activity of cellulose degradation enzyme.The results show that: At 3h, 5mg/kg Mo group of pH was significantly lower than other groups(p<0.05). Compared with the control group, the ammonia nitrogen concentration of experimental group was significantly(p<0.05) increased and the concentration of Microbial protein was significantly(p<0.05) decreased. The activity of cellulase, carboxymethyl cellulose and cellulase in 10mg/kg group were significantly higher than those in control group(P<0.05).(2)A 3 × 3 Latin square experiment was used in vivo experiment. The sheep were respectively fed a basal diet with no Mo addition and the diet supplied with 30mg/kg(30mg Mo/kg body weight) and 60mg/kg(60mg Mo/kg body weight). The experiment was divided into three stages. Fluid was collected from the rumen fistula at 0h, 4h, 8h, 12 h and 24 h of each test period. p H 、 NH3-N concentration 、 MCP concentration 、 the activity of cellulose degradation enzyme and the number of rumen bacteria、Cellulolytic bacteria and fungi were determined.The results show that: rumen pH value was in the range of 6.15~7.05. 30mg/kg and 60mg/kg Mo had no significant(p>0.05) effect on rumen pH. Mo in the level of 30mg/kg and 60mg/kg significantly(p<0.05) decrease NH3-N concentration, and 60mg/kg Mo could force a bigger decline. Compared with the control group, 60mg/kg Mo significantly(p<0.05) increased the activity of carboxymethyl cellulose, and 30mg/kg Mo significantly(p<0.05) decreased the activity of two cellulase enzymes. Compared with the control group, the total bacterial count of 60mg/kg group at 4h was significantly increased and that of 30mg/kg group in 12-24 h was significantly increased. The number of fibrous decomposing bacteria in 30mg/kg and 60mg/kg group was more than that in control group. The total fungi count of 60mg/kg group at 4h was significantly higher and that of 30mg/kg group in 8h was significantly lower than that in the control group.Conclusion:(1) in vitro culture conditions, 5mg/kg、10mg/kg and 15mg/kg Mo can improve in vitro fermentation condition of the mixed rumen microorganism and promote ammonia production and utilization; 10mg/kg Mo can increase cellulose, carboxymethyl cellulose and fiber disaccharidase activity, promoting the metabolism of cellulose.(2) 30mg/kg and 60mg/kg Mo can significantly increase the number of bacteria, fiber decomposing bacteria and fungi,promoting rumen fermentation.