Lysozyme as an alternative to antibiotics improves growth, antioxidants status, immunity, and intestinal bacteria in broiler chickens during the fattening period

Abstract. The present study aimed to evaluate the impact of dietary lysozyme levels on the growth performance, hematological and blood biochemical parameters, immunity, antioxidant capacity, and intestinal microbial count in broiler chickens. Three-hundred 1 d old birds (Cobb-avian500) were used and divided into five groups (five replicates per group, 60 birds per replicate). Birds in the first group were fed a control diet, while birds in the second, third, fourth, and fifth groups were fed the control diet with 0.2 g lincomycin, 1 g commercial lysozyme, 25 mg chicken egg lysozyme, and 50 mg egg lysozyme per kg of diet, respectively. Results confirmed that, in comparison with the control diet, all supplements had greater impacts on final body weight and body weight gain, and only the egg lysozyme diet (50 mg kg−1 diet) increased feed intake. Lincomycin, commercial lysozyme, and egg lysozyme (25 mg) improved the feed conversion ratio (FCR). Birds fed commercial lysozyme and egg lysozymes showed significantly increased hemoglobin and red blood cell counts. All supplements reduced white blood cells, heterophils, and heterophils / lymphocytes ratio and increased lymphocytes. All supplements significantly increased serum total protein, albumin, globulin, and glucose. The diet of egg lysozyme (50 mg kg−1) significantly decreased alpha-globulin, alanine aminotransferase, triglycerides, cholesterol, and urea levels and increased high-density lipoproteins. Diets with lincomycin, commercial lysozyme, and egg lysozyme significantly increased antioxidant capacity and decreased malondialdehyde (MDA). The interferon-gamma (IFNγ) and interlukin-2 (IL-2) were significantly improved by lincomycin, commercial lysozyme and egg lysozyme diets, but interlukin-10 (IL-10) was significantly increased only by the egg lysozyme (50 mg kg−1) diet. The total bacterial count, Salmonella, Escherichia coli, and Proteus counts were significantly decreased. Dressing rate and breast weight percentage were significantly increased by the egg lysozyme (50 mg kg−1) diet. Thigh weight percentage was increased only by the commercial lysozyme diet. In conclusion, chicken egg lysozyme (50 mg kg−1), a promising alternative for antibiotics in broiler chickens' diet, can enhance growth performance, antioxidant status, immunity, and intestinal bacteria.