<p>This study was conducted to determine if adding the acid-tolerant engineered bacterial strain M. elsdenii H6F32 to the rumen of sheep would reduce the risk of lactic acidosis. Lactic acidosis were induced by feed challenges in three groups of six sheep intraruminally dosed with wheat. In each group, sheep were not supplemented(C) or supplemented with the original bacterial strain M.elsdenii H6(H6) or the acid-tolerant engineered bacterial strain M.elsdenii H6F32(H6F32). Compared with C, the concentrations of ruminal lactic acid were decreased and the pH were increased both in H6 and H6H32(P&lt;0.05). Moreover, the engineered strain H6H32 had the much better ability to decrease lactic acid and increase pH. Meanwhile, a greater concentrations of total VFA were in H6F32. The concentrations of ruminal acetate and butyrate in H6F32 were lower than that in C and H6. However, the propionate was much higher in H6F32. Conclusions about protection against lactic acidosis by the acid-tolerant bacterial strain M. elsdenii H6F32 could be reached. It may be that the engineered strain H6F32 could grow well and increases the microbial fermentative activity and increased VFAs production in the rumen at the expense of lactate during the lactic acidosis challenge.&nbsp;</p>


<p>Evaluation of the protective effect of the acid-tolerant engineered bacterial strain M. elsdenii H6F32 as a probiotic fed to sheep during&nbsp;the lactic acidosis challenge</p>


<div style="text-align: justify;">This experiment was conducted to investigate the effects of certain long-chain fatty acid combinations on ruminal microbial community in vitro. Three cows fitted with permanent ruminal cannulas were used to provide rumen liquor for the in vitro trail. The treatments were fatty acid combinations of stearic acid, oleic acid, linoleic acid and linolenic acid, which respectively were group A (calcium palmitate, control), B (1.5%, 1.0%, 0.5% and 1.5%, acetic type fermentation), C (1.5%, 1.0%, 1.5% and 1.0%, propionic acid type fermentation), D (1.0%, 1.5%, 1.5% and 0.5%, butyric acid type fermentation). Three goats fitted with rumen cannula were used to provide the culture medium was collected for the measurement of the rumen microorganism in vitro culture. Culture medium was collected at 0, 3, 6, 12, 18 and 24 h. The results demonstrated that, except for Ruminococcus albus, all the other bacterial genus had significant differences between groups (P &lt; 0.05). The Fibrobacter succinogenes and Ruminococcusflavefaciens, Clostridium proteoclasticum and Ruminobacter amylophilus were higher in group B; Butyrivibrio fibrisolvens, Megasphaera elsdenii and Ruminococcus bromii were higher in group C; while Pseudobutyrivibrio ruminis was higher in group D. Different higher species in different treatments described above related to their fermentation type. It was also observed that, bacteria were the dominant flora in rumen and Megasphaera elsdeniiwere the dominant species in bacterial fraction no matter what the treatment is. It was therefore concluded that, certain fatty acid combinations have remarkable effects on the amount of ruminal specific bacteria species,mainly related to their fermentation type.</div>

Evaluation of the protective effect of the acid-tolerant engineered bacterial strain M. elsdenii H6F32 as a probiotic fed to sheep during the lactic acidosis challenge

Effects of certain long-chain fatty acid combinations on the ruminal microbe species relating to fermentation type in vitro