PIG GROWTH PROMOTION BY ANTIMICROBIALS IS ASSOCIATED WITH ENHANCED INTESTINAL BARRIER FUNCTION

Antimicrobial additives (AMA) have long been used to treat infections and promote pig growth. Published evidence suggests that some AMA have a direct anti-inflammatory effect on the intestine. Therefore, it seems reasonable to expect that the growth-promoting effect of AMA may be related to improvements in the gut barrier function. To test this hypothesis, 24 piglets were weaned (5.8 ± 0.34 kg), housed individually, and fed standard pre-starter (from weaning to d 14) and starter (from d 15 to d 42) diets without (CON, n = 12) or with (AMA, n = 12) antimicrobial compounds (pre-starter, 40 g/T tiamulin, 400 g/T chlortetraciclin and 2500 g/T zinc oxide; starter, 40 g/T tiamulin, 110 g/T chlortetraciclin and 2500 g/T zinc oxide). On d 42, segments of mid-ileum were harvested from 8 pigs/treatment and mounted on Ussing chambers for measurements of trans-epithelial electrical resistance (TER) and short circuit current (Isc ). On average, animals in the AMA group did not consume more feed (507 vs 480 g/d), but gained more BW (377 vs 328 g/d, P < 0.01) and grew more efficiently (0.82 vs 0.78; P < 0.01) than CON pigs. As a result, AMA animals finished the study with a higher BW (18.7 vs 16.8; P < 0.01). Furthermore, AMA increased TER (163 vs 115 Ω∙cm2 , P = 0. 02) and decreased Isc (2.2 vs 6.1 μA cm2 ; P < 0.05). In conclusion, AMA feed supplementation resulted in improved animal growth and this response was associated with improved gut barrier function tech.service@fad.com