230 Effect of Supplementing a Bacillus Spp-Based Probiotic on Performance, Body Temperature, and Intestinal Histology of Heat Stressed Pigs

Abstract

Abstract The integrity of the small intestine epithelia may become compromised when pigs are exposed to heat stress (HS) increasing the risk of health deterioration. Dietary supplementation with probiotics can help animals to maintain a healthy intestinal environment. An experiment was conducted with 80 pigs [21.6 ± 3.4 kg body weight (BW); 2 pigs/pen] exposed to either HS or thermal neutral (TN) conditions to evaluate the effect of supplementing the diet with a Bacillus subtilis DSM 32540 based probiotic on performance, body temperature, and intestinal histology. Treatments were: TN pigs fed a control diet without (TN-C) or with 0.05% probiotic (TN-P), and HS pigs fed a control without (HS-C) or with 0.05% probiotic (HS-P). The control diet (1.05% SID Lys) adequate in all nutrients was formulated with wheat, soybean meal, and feed-grade Lys, Thr, and Met. Feed and water were freely available during the 21-days (d) experiment. At the end, pigs were sacrificed to collect intestinal samples from duodenum, jejunum, and ileum to analyze the epithelia histology. Additionally, 12 ileal cannulated pigs kept in the HS room fed the same diets (6/diet) were implanted with a thermometer that registered body temperature (BT) at 5-min intervals. Ambient temperature (AT) inside the HS and TN rooms ranged from 19 to 25 °C and from 30 to 38.5 °C, respectively. The BT of HS-P pigs was less than that of HS-C pigs from 1400 to 2400 h (P< 0.05). There was no diet x AT interaction effect for performance variables. Body weight gain, feed intake, and gain:feed was less but respiration rate was greater in HS than in TN pigs regardless of the diet (P < 0.01). Probiotic supplementation increased BW gain and gain:feed (P < 0.05) of both TN and HS pigs, but feed intake was not affected. Exposure to HS decreased villi height in jejunum and ileum, but increased crypt depth and villi height:crypt depth in duodenum, jejunum, and ileum (P < 0.05). Probiotic supplementation increased villi height in duodenum and ileum, whereas crypt depth decreased but villi height:crypt depth increased in the three segments of the small intestine (P < 0.05). These data confirm the negative effect of HS exposure on performance, body temperature, and intestinal histology of pigs. These results also suggest that supplementing with 0.05% Bacillus subtilis DSM 32540 probiotic may help to counteract the negative effects of HS on performance and intestinal histology of pigs.