PSI-30 - Effects of high canola meal diet with acidifiers supplementation on cecal microbiota of nursery pigs

Abstract: Inclusion of canola meal (CM) in swine diets is typically limited stemming from the presence of glucosinolates (Gls), which can reduce growth performance and cause thyroid dysfunction in nursery pigs. While certain members of hindgut bacterial communities are capable of degrading dietary Gls, which would mitigate their detrimental effects, they have yet to be identified. Moreover, lowering the pH in the pig's hindgut can break down Gls into less toxic compounds, potentially reducing harm. Thus, this study aimed to characterize major bacterial species populating the hindgut of nursery pigs fed a high CM diet supplemented with acidifier and encapsulated butyrate. A total of 315 nursery pigs weaned at 21 days old, average body weight 6.0 ± 1.2 kg, were assigned to one of five dietary treatments with 9 replicate pens (7 pigs/pen) in a randomized complete block design. The dietary treatments included PC: a corn-soybean meal-based diet with 20% CM, NC: a corn-soybean meal-based diet with 40% CM, NC+A: NC diet supplemented with an acidifier at 1,500 ppm, NC+B: NC diet supplemented with encapsulated butyrate at 500 ppm, and NC+A+B: NC diet supplemented with both an acidifier and encapsulated butyrate. All diets were formulated to meet or exceed the nutrient requirements of NRC (2012). At the end of the feeding trial (6 weeks), one pig from each pen was euthanized to collect fresh cecal digesta. Samples were analyzed using the 16S rRNA gene through PCR-amplification of the V1-V3 regions from microbial genomic DNA, followed by Illumina MiSeq 2X300 sequencing. A comparative analysis of the highly represented taxonomic groups and operational taxonomic units (OTU) using non-parametric Kruskal-Wallis sum-rank test and Wilcoxon pairwise test identified candidate bacterial groups or species enriched across different diets. Bacillota was the predominant phylum across all diets, ranging from 83.2% to 86.3%. At the genus level, Lachnospiracea incertae sedis was less abundant in the NC diets with acidifier (Acidifier effect, P < 0.05), whereas Dialister was lower in the NC diets with encapsulated butyrate (Butyrate effect, P < 0.05). The OTU Ssd-00001 (Lactobacillus amylovorus, 99.6%) tended to be higher in the cecal microbiota of pigs fed the NC diets with acidifier (Acidifier effect, P = 0.09). Interestingly, OTU Ssd-00188 (Agathobacter rectalis, 99.2%) tended to be higher in PC diet than in NC diet (P = 0.06), while its abundance was lower in the cecal microbiota of pigs fed the NC diets with acidifier (Acidifier effect, P = 0.09). In conclusion, these results provide valuable insights into the microbiome of pigs fed high CM diets. Understanding the interplay between microbial communities and high CM diet with acidifier supplementation is crucial for optimizing swine diets and mitigating challenges associated with the antinutritional effects of dietary Gls from CM.