PSXIII-8 Effects of Dietary Lactobacillus Reuteri on Immune Responses, Blood Profiles, Intestinal Morphology, and Ileal Gene Expression of Weaned Pigs

Abstract

Abstract Weaning period is critical for gut health and immunity of pigs due to negative effect of weaning stress. Probiotics can be a potential alternative to antibiotics. However, there is limited information on potential mechanism of gut health and immunity of dietary Lactobacillus reuteri. This study was conducted to investigate the effects of dietary Lactobacillus reuteri on immune responses, blood profiles, intestinal morphology, and ileal gene expression of weaned pigs. A total of 48 weaned pigs [average initial body weight (BW) = 6.51 ± 0.87 kg; 21 days old] were allotted to 2 dietary treatments in a randomized complete block design (block: initial BW and sex). Dietary treatments had 6 replicate pens with 4 pigs per pen and fed for 4 weeks. Dietary treatments consisted of a basal weaner diet based on corn-soybean meal (CON) and CON supplemented with 0.02% Lactobacillus reuteri IDCC 3701 (LR). The LR was obtained from a commercial company (ILDONG Bioscience Co., Ltd., Pyeongtaek, Republic of Korea). Blood samples were collected from randomly selected one pig per pen on day 1, 7, 14, and 28. Serum was obtained from the blood sample to measure immune responses. On the last day of the experiment, the pigs were euthanized to collect small intestinal segments for intestinal morphology. Ileal mucosa were collected from ileal tissue for gene expression analysis. Measurements were serum cortisol, tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), interleukin-1β (IL-1β), and interleukin-6 (IL-6) using ELISA kits, blood profiles using an automated hematology analyzer, intestinal morphology using hematoxylin and eosin method, and ileal gene expression of tight junction proteins and inflammatory cytokines using qRT-PCR. Data were analyzed by using PROC GLM of SAS. Experimental unit was a pen. Statistical model for immune responses, blood profiles, and intestinal morphology included dietary treatments as a main effect and initial BW as a covariate. The t-test was used for the comparison of ileal gene expression. Pigs fed LR had drecreased (P < 0.05) serum TNF-α and IL-6 on day 7 and serum TGF-β1 on day 14 than those fed CON. In addition, pigs fed LR had greater (P < 0.05) hemoglobin concentration on day 7 than those fed CON, but had reduced (P < 0.05) hematocrit on day 14. Pigs fed LR had greater (P < 0.05) villus height to crypt depth ratio in duodenum than those fed CON. The LR upregulated (P < 0.05) claudin-1 gene compared with CON, but downregulated (P < 0.05) interleukin-8 and TNF-α genes. In conclusion, addition of dietary Lactobacillus reuteri in weaner diets improved intestinal morphology, modulated blood profiles and immune responses, and gene expression of inflammatory cytokines.