Effects of exogenous tannase enzyme on growth performance, antioxidant status, immune response, gut morphology and intestinal microflora of chicks fed grape pomace

Abstract

An experiment was conducted to study the effects of dietary addition of tannase to feed of chicks including grape pomace (GP) on growth performance, antioxidant status, immune response, blood parameters, gut morphology, intestinal microflora, liver function, and histopathological responses. The experimental diets were i) control (corn and soybean diet) (C); ii) C+10%GP; iii) C+10%GP+T1 (500 mg/kg tannase enzyme); and iv) C+10% GP+T2 (1000 mg/kg tannase enzyme). At 10 days old, the bodyweight (BW) and average daily gain (ADG) of the birds fed the diet supplemented with GP was lower compared with the control group. In contrast with the control, supplementation of diets with 10%GP+1000 mg/kg tannase elevated superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and depressed the malondialdehyde (MDA) level in serum. The addition of GP to the chicken diets had a significant impact on the total anti- sheep red blood cells (SRBC) titers and IgG, and IgM antibodies at 21 and 42 days old. The muscularis thickness of the chicken duodenum decreased in the Trial 3 compared with control groups. The inclusion of GP in the chicken diets reduced the concentration of Escherichia coli and increased that of Lactobacillus compared with the control. The results of the present study suggest that the inclusion of up to 10 percent GP in diets did not adversely affect broiler growth performance, and supplementation of tannase improved the antioxidant status and immune responses,and increased the caecal populations of beneficial bacteria in the cecum of broiler chickens.

Keywords: Broiler chickens, histopathological responses, glutathione peroxidase, polyphenol, sheep red blood cells