LAUSR

Abstract This study was performed to investigate the effects of curcumin supplementation on intestinal barrier function, serum biochemical index, amino acid profile, and mRNA expression of nutrient transporters in laying hens fed soybean meal with heat-induced protein oxidation. A total of 288 40-week-old Hy-Line Brown laying hens were allocated into one of three treatments with eight replicates of twelve birds each for a 42-day feeding trial. The birds were fed a soybean meal-corn basal diet and a heated soybean meal (HSBM)-corn basal diet supplemented with or without 150 mg/kg curcumin. HSBM increased circulating diamine oxidase activity and D-lactate levels, and curcumin reduced D-lactate concentrations in birds fed HSBM (p < .05). Birds fed HSBM exhibited a decreased mRNA abundance of occludin and claudin 3 in the intestinal mucosa, and downregulation of claudin 3 expression was reversed by curcumin (p < .05). HSBM decreased total protein and albumin levels in the serum, both of these levels being increased with curcumin (p < .05). The administration of curcumin reversed HSBM-induced downregulation of amino acid concentrations in the serum, liver and yolk to control levels (p < .05). Moreover, HSBM decreased mRNA expression levels of amino acid transporters, glucose transporters, and peptide transporters in the intestinal mucosa, and curcumin almost completely reversed these effects, restoring expression levels of these genes to the control values (p < .05). The results of this study indicate that curcumin administration can alleviate the intestinal barrier injury and compromised nutrient absorption induced by HSBM in laying hens. HIGHLIGHTS Protein oxidation of heated soybean meal (HSBM) impaired the intestinal barrier function of laying hens. Curcumin treatment attenuated the intestinal barrier injury induced by HSBM. Curcumin treatment improved the reduced nutrient absorption and transport of hens fed HSBM.