RESUMEN
AIM: Establishment of ruminal bacterial community in dairy calves. METHODS AND RESULTS: Rumen bacterial community was analysed on 6 calves bred according to commercial practices from day one to weaning at day 83 of age, using 454 16S rRNA-based pyrosequencing. Samples taken at day 1 did not produce amplicons. Analysis of data revealed a three-stage implantation process with a progressive but important shift of composition. At day 2, the bacterial community was mainly composed of Proteobacteria (70%) and Bacteroidetes (14%), and Pasteurellaceae was the dominant family (58%). The bacterial community abruptly changed between days 2 and 3, and until day 12, dominant genera were Bacteroides (21%), Prevotella (11%), Fusobacterium (5%) and Streptococcus (4%). From 15 to 83 days, when solid food intake rapidly increased, Prevotella became dominant (42%) and many genera strongly decreased or were no longer detected. A limited number of bacteria genera correlated with feed intake, rumen volatile fatty acids and enzymatic activities. CONCLUSION: The ruminal bacterial community is established before intake of solid food, but solid food arrival in turn shapes this community. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides insight into the establishment of calves' rumen bacterial community and suggests a strong effect of diet.
Asunto(s)
Bacterias/crecimiento & desarrollo , Dieta/veterinaria , Rumen/microbiología , Animales , Animales Recién Nacidos , Animales Lactantes , Bacterias/clasificación , Bacterias/genética , Bacteroides/clasificación , Bacteroides/genética , Bacteroides/crecimiento & desarrollo , Bacteroidetes/clasificación , Bacteroidetes/genética , Bacteroidetes/crecimiento & desarrollo , Bovinos , Calostro/microbiología , ADN Bacteriano/química , ADN Ribosómico/química , Dieta/clasificación , Ácidos Grasos Volátiles/análisis , Femenino , Fusobacterium/clasificación , Fusobacterium/genética , Fusobacterium/crecimiento & desarrollo , Masculino , Pasteurellaceae/clasificación , Pasteurellaceae/genética , Pasteurellaceae/crecimiento & desarrollo , Prevotella/clasificación , Prevotella/genética , Prevotella/crecimiento & desarrollo , Proteobacteria/clasificación , Proteobacteria/genética , Proteobacteria/crecimiento & desarrollo , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Rumen/enzimología , Rumen/metabolismo , Streptococcus/clasificación , Streptococcus/genética , Streptococcus/crecimiento & desarrollo , DesteteRESUMEN
The acid end-products of 185 isolates from the family Bacteroidaceae were separated and analysed by gas-liquid chromatography on broth cultures. Different media were evaluated and definitive studies were performed in a fully supplemented complex medium. The limitations of this approach to the identification of a wide range of strains from various clinical sources were determined and the results were compared with those of a series of morphological, biochemical, tolerance and antibiotic-resistance tests. All test strains were identified to generic level by simple microscopic and colonial observations and GLC analysis; additional tests were required to allow species or subspecies identification of most strains. Population differences were detected between some species or subspecies isolated from different clinical sites by quantitative analyses of fatty acids, but individual strains could not always be separated because of overlapping ranges of distribution of acids that were common products of more than one species or subspecies. Small differences in minor products between different species or subspecies were variable and are not considered adequate for discrimination at these taxonomic levels without support from other observations. The potential application of the GLC technique to the rapid and accurate identification of these organisms in hospital laboratories is considered.