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Fourteen Holstein cows of similar ages were monitored through their first two lactation cycles, during which ruminal solids and liquids, milk samples, production data, and feed consumption data were collected for each cow during early (76 to 82 days in milk [DIM]), middle (151 to 157 DIM), and late (251 to 257 DIM) lactation periods. The bacterial community of each ruminal sample was determined by sequencing the region from V6 to V8 of the 16S rRNA gene using 454 pyrosequencing. Gross feed efficiency (GFE) for each cow was calculated by dividing her energy-corrected milk by dry matter intake (ECM/DMI) for each period of both lactation cycles. Four pairs of cows were identified that differed in milk production efficiency, as defined by residual feed intake (RFI), at the same level of ECM production. The most abundant phyla detected for all cows were Bacteroidetes (49.42%), Firmicutes (39.32%), Proteobacteria (5.67%), and Tenericutes (2.17%), and the most abundant genera included Prevotella (40.15%), Butyrivibrio (2.38%), Ruminococcus (2.35%), Coprococcus (2.29%), and Succiniclasticum (2.28%). The bacterial microbiota between the first and second lactation cycles were highly similar, but with a significant correlation between total community composition by ruminal phase and specific bacteria whose relative sequence abundances displayed significant positive or negative correlation with GFE or RFI. These data suggest that the ruminal bacterial community is dynamic in terms of membership and diversity and that specific members are associated with high and low milk production efficiency over two lactation cycles., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Aims: To measure the impact of supplementing a forage diet with tree-based browse on the ruminal bacterial communities of Nigerian West African Dwarf (WAD) sheep., Methods and Results: Fifteen WAD sheep were fed a control diet of forage (Panicum maximum), with 12 animals shifted in groups of three to one of four browse-supplemented diets (Albizia saman, Bridelia micrantha, Ficus sur, or Gmelina arborea). These browse plants were shown in a concurrent but separate study to be reasonably nutritious (based on chemical composition and fibre constituents) and nontoxic (based on tannin, phytate, saponin, alkaloid and oxalate levels). Rumen liquids and solids for DNA extraction were collected via intubation from two animals in each group before and after dietary shift. Bacterial 16S rRNA gene regions V6-V8 were sequenced by 454 pyrosequencing. All communities were highly diverse and dominated by the phyla Firmicutes, Bacteroidetes, Tenericutes, Actinobacteria and Proteobacteria. All communities shared members of the genera Butryivibrio, Prevotella and Ruminococcus. Our analysis defined a core sets of bacteria shared by all animals, forage-fed animals and browse-fed animals. Community structure shifted dramatically in animals fed A. saman or G. arborea., Conclusions: The impact of tree-based browse on the ruminal bacterial community of Nigerian WAD sheep varies by browse species, likely due to differences in browse composition., Significance and Impact of the Study: Our study describes the first neotropical small ruminant bacterial microbiome and supports diet supplementation with specific tree-based browse for WAD sheep., (© 2014 The Society for Applied Microbiology.)