Ruminant Nutrition: General

摘要

The objective of this study was to evaluate the ruminal microbial communitycomposition changes by feeding Lactobacillus plantarum asdirect-fed microbials (DFM) in high-producing dairy cows’ diets. A dual-flow continuous culture system was used in a replicated 4x4 Latinsquare design. A basal diet was formulated containing 16% protein and28% starch and the treatments were: the basal diet without DFM (CTRL);a mix of Lactobacillus acidophilus at 1 × 109cfu/g and Propionibacteriumfreudenreichii at 2 × 109 cfu/g (MLP = 0.01% of diet DM); and 2levels of L. plantarum at 1.35 × 109 cfu/g (L1 = 0.05% and L2 = 0.10%of diet DM). Bacterial samples were collected at 0, 2, 4, 6, and 8 h afterfeeding from the effluent containers; a composite of all time points wasmade for each fermenter. The microbial community composition was analyzedthrough sequencing the V4 region of the 16S rRNA gene usingIllumina MiSeq platform. Sequencing data were analyzed on QIIME andstatistical analysis was performed with R and SAS; orthogonal contrastswere used to compare treatments. The most abundant phyla from all sequenceswere Bacteroidetes and Firmicutes, with 42% and 34% of relativeabundance, respectively. At the family level, all DFM treatmentsdecreased the relative abundance of Lachnospiraceae (P = 0.03), Pirellulaceae(P = 0.05), and Paracaedibacteraceae (P = 0.02) populations,while L. plantarum inclusion positively affected the abundance of Anaeroplasmataceae(P = 0.04). Interestingly, the Lactobacillaceae familywas not detected in our analysis, which may indicate a low survival rateof the tested DFM in the ruminal fluid. Relative abundance of 9 genera(mostly fibrolytic and proteolytic) decreased with the DFM inclusion,with emphasis on Butyrivibrio spp. (P = 0.01), while 1 genus increasedwith DFM inclusion (Ruminococcaceae UCG-002; P = 0.02). Thesefindings help to explain why DFM inclusion decreased NH3-N concentration,while pH and lactate concentration were not affected by treatments.