Ruminant Nutrition: Dairy - Feedstuffs

ferent among treatments. Protozoal counts were not different among treatments (P > 0.05) in ruminal or omasal samples. Generic protozoal counts were not different (P > 0.05) among treatments, corresponding with similar banding profiles from DGGE. Multivariate statistics showed no difference (P > 0.05) in generic distribution of protozoa in ruminal vs. omasal samples, supporting absence of selective retention of Isotrichs in the rumen. Extracted DNA from omasal contents was amplified in PCR using S926f and L189r primers for RIS-LP analysis. Amplicons containing the complete RIS and parts of the flanking rRNA genes were separated on a 4% polyacrylamide gel. The RIS-LP gel image was exported into image analysis software. Cluster analysis of banding profiles grouped the treatments together, suggesting that bacterial populations differed among treatments. Source of methionine appeared to change ruminal bacterial but not protozoal populations. Future research will characterize bacterial populations altered by HMB supplementation.