Study On Variation Of Rumen Internal Environment And Related Blood Index In Angus Hybridization Beef Cattle At Different Feeding Stages

To explore the change law of rumen environment and correlative blood index of angus hybridization beef cattle at different feeding stages, and in order to master the situation of subacute rumen acidosis in angus hybridization beef cattle, the change law of rumen p H value, volatile fatty acid, blood cell factor, blood biochemistry, blood endotoxin and rumen bacterial in each group of beef were studied in this paper. 30 different breeding stages experimental cattle were choosed in a farm of Hu-nan.They were divided into five groups, weight at 300 kg(I), 350 kg(II), 400 kg(III), 550 kg(IV) and 650 kg(V). With increase of age and weight, the rumen pH decreased significantly. Acetic acid, propionic acid and butyric acid content was tested by ion chromatography, it showed that the total VFA increased gradually.Through the radioimmunoassay method, blood cell factor content was tested. It was found that the content of TNF-α in blood just have been slight oscillations in different stages of the beef cattle, but the content of IL-1 and IL-6 tend to increase. Blood endotoxin levels were determined by tachypleus amebocyte lysate method, the result showed that blood endotoxin levels of group III increased significantly.The result of blood biochemistry showed that increasing dietary concentrate levels led to gradual increase of ALT, GGT, AST in liver, except ALP tended to decrease. The liver enzyme activity was weaken at the later fattening stage. The content of TP of group II rose to its highest level, then became to decline. Five rumen bacteria number was detected by fluorescence quantitative polymerase chain reaction, it was found that the content of bacteria in group II increase significantly at he early fattening stage.The increasing degree of ruminobacter amylophilus in group III is most palpable. Since mid fattening stage, the number of five kind of bacteria reduce in various degree.The number of cellulose decomposition microbes as early as in starch degradation bacteria. Various microbes in the late fattening content is basic stable, showed no significant difference.In summary, the above results indicated that accumulation of VFA in rumen was the main reason of lower ruminal pH with the development of feeding stage. The results of correlative blood index showed that long-term high level concentrated feeds can damage to the liver.However the SARA symptoms relieved slightly in the later fattening stage, it may be attribute to angus hybridization beef cattle can adjust themselves to alleviate harmful influence.