Effects Of Subacute Rumen Acidosis On Rumen Fermentation And Populations Of Ruminal Bacteria

XI GuanZhong lactating goats were used in the reaserch .They were induced to SARA state by increasing concentrate ratio gradually.The trial was divided into four stages, the ratio of concentrate and roughage were respectively 5:5, 6:4, 7:3 and 8:2. Ruminal pH was monitored in 24 hours uninterruptedly and the monitoring results showed that the goats were occured SARA on the level of 80% concentration.Oligonucleotide probes to 16S rRNA,traditional cultivation method and Real-Time PCR were used to explore rumen bacteria,Amylolytic bacteria,lactate-metabolizing bacteria (Strepococcus bovis,Lactobacillus,Selenomonas ruminantium and Megasphera elsdenii),lactate-utilizing bacteria (Selenomonas ruminantium,Megasphera elsdenii), three main Cellulolytic bacterias, the variation of protozoa counting in the SARA state and to reveal the rumen fermentation mechanism under that condition.The results showed that:1. In SARA state ,the concentration of TVFA was increased significiently( P<0.05) . VFA has the highest increase amplitude,and that maybe the main factor leading to SARA .Meanwhile,the level of lactate was low, and has less association to SARA.2. With the concentrate ratio enhancing , the total bacteria count was increased gradually. The population of Amylolytic bacteria increased significantly (P<0.01).3. In SARA state ,the population of Lactobacillus,Strepococcus bovis,Selenomonas ruminantium and Megasphera elsdenii were increased at different levels. The quantities of the three main Cellulolytic bacterias were decreased Significantly(P<0.05).4. With the concentrate ratio enhancing ,the population of protozoa counting was increased at first and then decreased, especially in SARA state( P<0.01)...