Effects of Dietary Supplementation of Myristic Acid on Intestinal Health and Growth Performance of Nursery Pigs

Hyunjun Choi, Gabriel Rocha, Sung Woo Kim

The objective of this study was to investigate the effects of myristic acid on intestinal health and growth performance of nursery pigs. Thirty-six newly weaned pigs (6.6 ± 0.4 kg BW) were assigned to 3 treatments (n = 12) in 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 + 0.25% bacitracin methylene disalicylate (antibiotic; bacitracin: 276 g/t feed) in all phases; and 3) MA: NC + myristic acid at 0.075% in phases 1 and 2 and 0.045% in phase 3. Diets contained nutrients meeting the requirement. Growth performance and fecal score were measured for each phase. Pigs were euthanized to collect jejunal mucosa, jejunal tissues, and ileal digesta. Data were analyzed using preplanned contrasts (NC vs. PC and NC vs. MA) in the Proc MIXED procedure of SAS. Compared with the NC, the PC improved (P < 0.05) ADG in phase 1 (43 to 101 g/d) and ADFI in phase 2 (458 to 578 g/d), whereas the MA improved (P < 0.05) ADG (541 to 668 g/d) and ADFI (801 to 996 g/d) in phase 3. Overall, the PC tended to improve ADG (353 to 419 g/d; P = 0.063), and ADFI (515 to 606 g/d; P = 0.051), whereas the MA improved (P < 0.05) ADG (353 to 431 g/d) and ADFI (515 to 623 g/d) compared with the NC group. The PC decreased (P < 0.05) fecal score (3.17 to 3.03) in phase 2 compared with the NC. The PC tended to decrease IL8 (P = 0.053; 0.53 to 0.37 ng/mg of protein) and protein carbonyl (P = 0.075; 2.65 to 1.66 nmol/mg of protein) in jejunal mucosa compared with the NC. The PC increased (P < 0.05) the villus height to crypt depth ratio (2.61 to 3.02) compared with that of NC. The MA tended to decrease IgG (P = 0.051; 2.44 to 1.67 µg/mg of protein) and IL8 (P = 0.090; 0.53 to 0.39 ng/mg of protein) in jejunal mucosa compared with that of the NC. The MA tended to increase relative abundance of Bacteroidetes (P = 0.075; 3.8 to 13.9) at phylum level, Prevotellaceae (P = 0.073; 3.7 to 13.8) at family level, and Prevotella (P = 0.085; 4.2 to 15.4) at genus level compared with the NC. In this study, it was shown that both bacitracin and myristic supplementation could improve the intestinal health and growth performance of nursery pigs. Effects of bacitracin on intestinal health and growth performance was rather immediate whereas the effects of myristic acid were obtained after a 3-week feeding.