Effects of lactic acid-producing bacteria as direct-fed microbials on the ruminal microbiome

Abstract

The objective of this study was to evaluate ruminal microbiome changes associated with feeding Lactobacillus plantarum GB-LP1 as direct-fed microbials (DFM) in high-producing dairy cow diets. A dual-flow continuous culture system was used in a replicated 4 × 4 Latin square design. A basal diet was formulated to meet the requirements of a cow producing 45 kg of milk per day (16% crude protein and 28% starch). There were 4 experimental treatments: the basal diet without any DFM (CTRL); a mixture of Lactobacillus acidophilus, 1 × 10 9 cfu/g, and Propionibacterium freudenreichii, 2 × 10 9 cfu/g [MLP = 0.01% of diet dry matter (DM)]; and 2 different levels of L. plantarum, 1.35 × 10 9 cfu/g (L1 = 0.05% and L2 = 0.10% of diet DM). Bacterial samples were collected from the fluid and particulate effluents before feeding and at 2, 4, 6, and 8 h after feeding; a composite of all time points was made for each fermentor within their respective fractionations. Bacterial community composition was analyzed through sequencing the V4 region of the 16S rRNA gene using the Illumina MiSeq platform. Sequenced data were analyzed on DADA2, and statistical analyses were performed in R (RStudio 3.0.1, https: / / www .r -project .org/ ) and SAS 9.4 (SAS Institute Inc.); orthogonal contrasts were used to compare treatments. Different than in other fermentation scenarios (e.g., silage or beef cattle high-grain diets), treatments did not affect pH or lactic acid concentration. Effects were mainly from overall DFM inclusion, and they were mostly observed in the fluid phase. The relative abundance of the phylum Firmicutes, family Lachnospiraceae, and 6 genera decreased with DFM inclusion, with emphasis on Bu-tyrivibrio_2, Saccharofermentans, and Ruminococcus_1 that are fibrolytic and may display peptidase activity during fermentation. Lachnospiraceae_AC2044_group and Lachnospiraceae_XPB1014_group also decreased in the fluid phase, and their relative abundances were positively correlated with NH 3 -N daily outflow from the fermenters. Specific effects of MLP and L. plantarum were mostly in specific bacteria associated with proteolytic and fibrolytic functions in the rumen. These findings help to explain why, in the previous results from this study, DFM inclusion decreased NH 3 -N concentration without altering pH and lactic acid concentration.

Effects of choline chloride on the ruminal microbiome at 2 dietary neutral detergent fiber concentrations in continuous culture

“…Abundance of phyla in the liquid fraction was dominated by Bacteroidetes (46.2% of sequences on average), whereas Firmicutes, Proteobacteria, Spirochaetes, Patescibacteria, and Fibrobacteres accounted on average for 25.8%, 12.2%, 8.2%, 1.3%, and 1.1%, respectively. Similar values of phylum relative abundances have been reported by Dai et al (2019) and Monteiro et al (2022) for samples collected from continuous-culture fermentors. We did not find any effect of Cho or NDF × Cho in the solid fraction; however, relative abundance of Firmicutes was greater for the 40% NDF diet, and conversely, Proteobacteria, Spirochaetes, and Patescibacteria were less abundant with the 40% NDF diet.…”

Effects of Lactic Acid Bacteria-Inoculated Corn Silage on Bacterial Communities and Metabolites of Digestive Tract of Sheep

“…P-treated silage decreased the relative abundance of Firmicutes in the rumen fluid. Similar results were reported by Monteiro et al [27], who fed high-producing dairy cows with Lentilactobacillus plantarum directly. The diet has a great influence on the rumen microbiota.…”

Combinations of bacterial cultures, exogenous enzymes, and yeast-based feed additives and their impact on ruminal microbiome

“…However, addition of microbial additives and enzymes (ADD) tended to decrease the relative abundance of Firmicutes in the solid fraction ( Table 2 ). Lower relative abundance of Firmicutes was reported by Monteiro et al (2022) for bacteria in the liquid fraction as a result of adding either Lactobacillus plantarum or a blend of Lactobacillus acidophilus and Propionibacterium freudenreichii to corn silage-based diets in continuous culture. Conversely, greater relative abundance of Firmicutes in ruminal fluid has been reported by Plaizier et al (2017) in cows with subacute ruminal acidosis resulting from a reduction of dietary NDF concentration, suggesting a positive association between Firmicutes relative abundance and ruminal acidity.…”

“…Moreover, in the liquid fraction we found that Prevotellaceae (20.9%), Succinivibrionaceae (20.0%), Lachnospiraceae (17.8%), Selenomonaceae (4.1%), and Spirochaetaceae (3.60%), were the most abundant families. Previous studies have already reported Prevotellaceae , Lachnospiraceae , Succinivibrionaceae , and Spirochaetaceae within the most abundant families in both solid and liquid fractions of ruminal cultures ( Arce-Cordero et al, 2022a ; Monteiro et al, 2022 ) and ruminal samples ( Söllinger et al, 2018 ).…”

“…For this experiment we used a dual-flow continuous culture based on the system originally developed by Hoover et al (1976) and recently used for ruminal microbiome studies ( Arce-Cordero et al, 2022a ; Monteiro et al, 2022 ). Conditions were maintained at continuous agitation (100 rpm), infusion of N 2 gas to displace oxygen, constant temperature (39 °C), and infusion of artificial saliva ( Weller and Pilgrim, 1974 ) with 0.40 g/L of urea, at 3.05 mL per minute to individually regulate passage rates of liquid (11% h −1 ) and solid (5.5% h −1 ) effluents of digesta.…”