Supplementation of a medium-chain fatty acid blend and a phytogenic feed additive improved performance of pigs challenged with Escherichia coli

    

This study was conducted to investigate the effects of medium-chain fatty acid blend (MCFA) and a phytogenic feed additive (Fresta® Protect, Delacon, Austria) on growth performance and gut health of Escherichia coli (ETEC)-challenged pigs. A total of 200 weaned pigs with initial body weight of 5.52 ± 0.17 kg were allotted to 40 pens (5 pigs/pen) blocked by BW and randomly assigned to 5 treatments: (1) negative control (NC), (2) NC + 55 mg/kg carbadox (positive control; PC), (3) NC + 0.6% MCFA, (4) NC + 0.1% phytogenic, or (5) NC + 0.6% MCFA and 0.1% phytogenic. The study lasted 18 d, and on d 5 and 6, all pigs were orally inoculated with 5 mL of ETEC (blend of F4 and F18+) with a final titer of 1010 cfu/pig. Body weights and feed intake were recorded on d 0 and 18, with additional weight of pigs on d 4 and 11. Fecal scores were assessed daily, and a fecal swab was collected on d 12 to analyze ETEC shedding. Data were analyzed using the lme4 package of R 4.1.2, with treatment as fixed effect and BW block as random effect. Contrasts were used to compare individual treatments to NC. During the pre-challenge period, pigs fed MCFA had less (P < 0.05) BW and ADG compared with NC group. Whereas in the post-challenge period, pigs fed PC and MCFA and phytogenic combination had greater (P < 0.05) final BW and ADG compared with NC, as well as phytogenic, improved (P < 0.05) ADG compared with NC. As overall performance, pigs fed PC and MCFA and phytogenic combination had greater (P < 0.05) ADG and G:F compared with NC pigs, and pigs fed MCFA had greater (P < 0.05) G:F than NC pigs. Stool quality was improved (P < 0.05) in pigs fed PC, MCFA, and MCFA and phytogenic combinations compared with NC pigs. In addition, probability of positive ETEC fecal shedding was numerically increased in pigs fed PC, phytogenic, and MCFA and phytogenic combination, and this likely resulted in the tendency to reduce mortality of pigs (2.5%) compared with NC pigs (15%). In conclusion, under ETEC challenge, supplementation of phytogenic alone or in combination with MCFA resulted in improved performance and reduction in mortality.

Key Words: Escherichia coli, feed additives, phytogenic, pig.