Development Of Microecologic Preparation For Subacute Ruminal Acidosis Of Beef Cattle And Its Effects

In recent years, increasing more concentrated feed could increase animals'production performance, at the same time, this bring about a risk of nutritional and metabolic diseases, especially rumen acidosis. Acute acidosis often causes animals'death. An incidence of sub-acute acidosis in beef is over 15%. The elimination rate of sub-acute acidosis in herd is more than 45% per year. In America, the direct economic loss caused by rumen acidosis in the fattening of beef is up to 0.6 to 1 billion dollars every year. Sub-acute rumen acidosis often occurs in the last stage of beef fattening.The striking decrease and an irregular undulate change of feed intake will lead to a decrease of production performance and feed conversion rate when the chronic acidosis happens. So diagnosis,prevention and cure is a key problem for sub-acute rumen acidosis in beef.This experiment develops a compound microbial pharmaceutics for subacute rumen acidosis in beef cattle though analysising the microfloras in different pH value of rumen in beef cattle and using T-RFLP and PCR technology with rumen micro-ecological theory, bacteria metabolic engineering strategy and the change of rumen function as the theoretical basis, and with the compound of lactic acid bacteria and yeast as the core technology. This will open up a new way for the prevention and control for rumen subacute acidosis in beef cattle.This experiment found when feeded with concentrated feed, the rumen selenomonas ruminantium significantly reduced, but megasphaera elsdenii and lactobacillus increased significantly (P<0.01); acetic acid concentration in the rumen significantly reduced (P<0.05), the change of propionic acid and butyric acid concentration is not obvious ( P>0.05 ) , lactic acid concentration increased significantly and accumulated in the rumen, that will cause subacute rumen acidosis.Through the determination of blood gas index and ion concentration we found that the PCO2 and the concentration of the Na2HCO3 in blood decreased with the decrease of the pH in the rumen of beef cattle with mild and moderatly subacute rumen acidosis, this suggest that a growing concentration of hydrogen ions in the blood was beyond the action of HCO3-buffer, the dynamic balance system of pH had been destroyed, subsequently resulted in compensative metabolic acidosis. A large number of lactic acide accumulated in the rumen leaded to body dehydration, secondary inflammation wich was characterized by an increase of the number of white blood cells. The decrease in the number of eosinophilic white blood cells suggested that toxic substances like histamine etc. might exist in the boody, especially the rumen. Neutrophils increased, lymphocytes decreased relatively with the nuclear type of neutrophils shifted to the left obviously, this is an important character of rumen acidosis.Screening the best yeast combination from saccharomyces cerevisiae, candida utilis, tropical candida with selenomonas ruminantium and megasphaera elsdenii, a rumen compound probiotics for sub-acute rumen acidosis of beef cattle was developed successfully. The probiotics can promote the use of lactic acid by candida utilis, tropical candida combined with selenomonas ruminantium and megasphaera elsdenii, restrain the further accumulation of lactic acid in vitro.The health beef cattle administered with the composite rumen probiotics had no change of analysising the blood biochemical index and testing the body metabolic function, which suggested that the composite rumen probiotics is safe non-toxic and reliable for beef cattle.When administered with the probiotics to the beef cattle with subacute rumen acidosis, the concentration of lactic acid in the rumen was decomposed and utilized, and returned to normal level fastly within 24h post-treatment. This initially proved that the probiotics is effective for subacute rumen acidosis of beef cattle.It is conclude that sub-acute rumen acidosis results from the accumulation of lactic acide in the rumen with the decrease of lactic acide–utilizing bacteria selenomonas ruminantium and the increase of lactic acide–generating bacteria lactobacillus. The probiotics combined saccharomyces cerevisiae, candida utilis, tropical candida with selenomonas ruminantium and megasphaera elsdenii is effective for subacute rumen acidosis of beef cattle through accelating the utilization of lactic acide in the rumen.