241 Immunophysiology and performance of broilers supplemented with macroalgal sulfated polysaccharides during a subclinical necrotic enteritis challenge

Abstract

Abstract This study evaluated the effects of a sulfate polysaccharide extracted from marine algae product on performance, intestinal lesion scores, and mRNA abundance of various tight junction proteins and immune response genes. A total of 600 one-day old male broilers (Ross 708) were allocated to one of four treatment groups (6 replicate floor pens, 25 birds/pen): negative control (NC) group fed a corn-soybean meal diet; positive control (PC) fed NC + 15 ppm Avilamycin and 125 ppm Amprolium, an additive group (AGS) fed NC + Algoguard added at 0.1% of the diet, and (AGH) fed NC + Algoguard added at 0.2% of the diet. To predispose the birds to NE, birds were orally gavaged with 2,000 Eimeria maxima sporulated oocysts on d 14 followed by a dose of approximately 1×108 CFU/mL of C. perfringens on d 19. On d 21, four birds/pen were necropsied for NE lesions and on d 14, 21, and 42 jejunal samples were collected to assess mRNA abundance. Birds and feed were weighed on d 14, 21, 28, and 42 on a per pen basis. Average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were calculated during each feeding phase and adjusted for daily mortality. The data were analyzed using ANOVA (JMP, Pro 16) and significance (P ≤ 0.05) was determined by the LSD test. During d 14-21, 0-21, 0-28, and 0-42, mortality rate and ADFI were significantly less in AGS, AGH, and PC compared with NC. ADG was greater while FCR was significantly less in PC, AGS, and AGH during d 21-28, 0-28, and 0-42 compared with NC (P ≤ 0.05). Lesion severity was also significantly less in AGS, AGH, and PC compared with NC. On d 14, 21, and 42 there were no toxins present in the tested serum samples. Calprotectin concentration was greater in PC and NC on d 21 and 42 compared with the supplemented groups. C. perfringens toxin was not detected in serum samples of any of the four treatment groups. mRNA abundance of CLDN1, IL1β, IL12B, and IL10 was greater in AGS compared with NC on d 14 and 42. ZO1 was significantly greater on d 21 in PC treatment and was less than both AGS and AGH on d 42 (P ≤ 0.05). Compared with all other treatments, mRNA abundance of OCLDN was greater and those of IFN-γ and ZO2 were less in PC, while that of CLDN3 showing no significant difference among all 4 treatments. To conclude, dietary inclusion of this algal product in broiler diets could be considered as a beneficial alternative to antibiotic growth promoters in the context of this challenge model.