Effects of diet and environment on microbial growth and efficiency

Thermal environment at 40°C was optimal for rumen bacterial growth determined with batch culture. Results from continuous culture system found no differences due to incubation temperature in microbial efficiency. Rumen microorganisms maintained normal growth and fermentation in the presence of increasing concentrations of AF, FMN and T-2. Thermal environment and adding AF did not alter MOEFF but changed bacteria composition. This suggests adjustment may be necessary to accurately predict flow of microbial DM during heat stress. Change in bacterial composition should be investigated to determine effects on growth of ruminal microorganisms subjected to chronic exposure to AF. FMN and T-2 changed rumen microbial fermentation in vitro. The effects of altered rumen fermentation caused by FMN and T-2 on animal performance should be investigated. Monensin did not alter MOEFF during prepartum and lactation phase. Monensin increased OMTD and propionic acid concentration which would increase energy available to the transition dairy cow.