| In order to study the effects of ration urea(non-protein nitrogen)supplement on rumen fermentation performance and blood biochemical indexes for Qinchuan beef cattle,we chose three adult bulls with rumen fistula to do the experiment.They were kept in the similar ration environment for 25 days.This process included five stages,each of which lasted for 30 days,25 daysforthe experimental treatment and the other five days as the buffer period.The proportions of urea addition at each stage were as follows: 0%(percentage of dry matter,the control group),0.5%(group A),1.0%(group B),1.5%(group C)and 2.0%(group D).At every experimental treatment stage,rumen liquid of bulls was collected for once every five days,and blood samples were collected at the last day.After that,we tested and analyzed the PH value,ammonia nitrogen(NH3-N),microbial protein(MCP),volatile fatty acid(VFA)and cellulolytic enzyme activity of rumen fermentation performance,as well as serum total protein TP,blood urea nitrogen BUN,alanine aminotransferase ALT and aspartate aminotransferase AST of blood biochemical indicators.The major results of the study are as follows:The first one was the effect of urea supplementation on rumen fermentation performance of Qinchuan beef cattle.According to the study,with the addition of urea,the PH value of rumen liquid showed a trend from decline to rise.There were great differences among each treatment group(P<0.05),and the lowest was 6.363±0.017(group B).The content of NH3-N in the four treatment groups was higher than that in the control groups(P<0.05).And the group D had the highest level,16.91±0.77 mg/dL.The content of microprotein in the treatment groups was higher than that in the control groups except group D(2.0%).Among these groups,the content of group B was 1.712±0.024 mg/mL,which had the highest level and had great differences between the control groups(P<0.05).The content of VFA in the treatment groups was higher than that in the control groups(P<0.05)except group D(2.0%),and group B(1.0%)was greatly different from the other control groups,with the highest level of 149.59±3.79 mmol/L.Compared with the control group,the indicators of group A(0.5%)and group B(1.0%)group are different greatly(P<0.05).What is more,there are few differences between these two groups except TVFA.There is a similar trend in the three kinds of cellulase activity,but the activity of group A(0.5%)and group B(1.0%)is higher than that of control groups and other treatment groups(P<0.05);There were no significant differences in various fermentation parameters of rumen fluid between fifth,tenth,fifteenth,twentieth,twenty-fifth days of each treatment stage(P>0.05).The second one was the effect of urea supplementation on blood biochemical indicators of Qinchuan beef cattle.According to the study,with the increase of urea,the blood biochemical indicators of cattle fluctuated within a normal range,including serum total protein(TP),blood urea nitrogen(BUN),alanine aminotransferase(ALT)and aspartate aminotransferase(AST).In this process,there were not obvious differences in the content of ALT among the treatment groups.While the indicators of ALT in the treatment groups were higher than those in the control groups.Group D had the highest level and was greatly different from the control groups and other treatment groups.In conclusion,the addition of urea in Qinchuan beef cattle's ration can effectively improve rumen ammonia nitrogen(NH3-N),microbial protein(MCP),acetic acid(C2),propionic acid(C3),cellulose hydrolase activity and so on.What's more,the blood biochemical indicators of cattle fluctuated within a normal range,including serum total protein(TP),blood urea nitrogen(BUN),alanine aminotransferase(ALP)and aspartate aminotransferase(AST).Therefore,there is a suggestion that two percent addition of urea the ration will be safe and the most suitable dosage is one percent. |
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