63 Impacts of dietary myristic acids on mucosa-associated microbiota in relation to intestinal health and growth parameters of nursery pigs

Abstract This study investigated the evaluate the role of dietary myristic acid on mucosa-associated microbiota for their relevance to intestinal health and growth performance of nursery pigs. A total of 36 newly weaned pigs [6.6 ± 0.4 kg body weight (BW)] were assigned to 3 treatments (n = 12/treatment) using a randomized complete block design with initial BW and sex as blocks. Pigs were fed for 35 d in 3 phases (10, 10, and 15 d, respectively). Treatments were 1) NC: basal diet; 2) PC: NC + 0.03% bacitracin in all phases; and 3) MA: NC + myristic acid complex at 0.20% in phases 1 and 2 and 0.12% in phase 3. Pigs were euthanized to collect jejunal mucosa and jejunal tissues for microbiome sequencing and measuring intestinal health parameters. Data were analyzed using preplanned contrasts (NC vs. PC and NC vs. MA) in the Proc MIXED procedure and correlation coefficients between microbiota and the intestinal health parameters were determined by the CORR procedure of SAS. The PC increased (P < 0.05) Lactobacillaceae (22.2 to 55.1%) compared with NC. The MA increased (P < 0.05) Veillonellaceae (1.7 to 5.2%), Lachnospiraceae (0.3 to 3.6%), Coriobacteriaceae (0.6 to 1.5%), and Ruminococcaceae (0.5 to 2.1%) and tended to increase (P = 0.072) Bifidobacteriaceae (6.9 to 18.2%) compared with NC. The PC increased (P < 0.05) Simpson (0.72 to 0.89) index and the MA increased (P < 0.05) Chao1 (124.3 to 221.0), Shannon (3.4 to 5.0), and Simpson (0.7 to 0.9) indexes compared with NC. The relative abundance (RA) of Helicobacteraceae was positively correlated with IL-8 (r = 0.63; P < 0.05) and protein carbonyl (r = 0.65; P < 0.05). The RA of Bifidobacteriaceae was negatively correlated with IgG (r = -0.51; P < 0.05), IL-8 (r = -0.58; P < 0.05), TNF-α (r = -0.46; P < 0.05), and protein carbonyl (r = -0.64; P < 0.05) whereas it was positively correlated with average daily gain (ADG; r = 0.51; P < 0.05) and average daily feed intake (ADFI; r = 0.49; P < 0.05). The RA of Lactobacillaceae negatively correlated with IL-8 (r = -0.59; P < 0.05) and protein carbonyl (r = -0.54; P < 0.05) whereas it was positively correlated with ADFI (r = 0.43; P < 0.05) and MDA (r = 0.44; P < 0.05). The RA of Veilonellaceae and Megasphaera sp were negatively correlated (r = -0.49; r = -0.61; P < 0.05) with IgG, respectively. In conclusion, MA mainly increased RA of Bifidobacterium and Megasphaera, whereas PC increased RA of Lactobacillus and Mitsuokella in the jejunal mucosa. The positive modulations of RA of mucosa-associated microbiota by PC and MA were strongly correlated with improved intestinal health and growth of nursery pigs.