To evaluate the whey protein (WP) sources on performance, liver antioxidants and immune responses of broiler chickens, 300 one-d-old male Ross 308 chickens were randomly allocated to 6 treatments with 5 replications of 10 birds each. Birds were challenged with ethanol 6% from 10 to 24 days of age. This study was based on a completely randomized design in a 3×2 factorial arrangement with dietary supplemental WP sources (no WP; 2% WP and 2%whey protein concentrate (WPC)) and ethanol (zero and 6%). Experimental diets were as follows; 1) no WP with ethanol, 2) WP with ethanol, 3) WPC with ethanol 4) no WP-no ethanol, 5) WP-no ethanol, 6) WPC-no ethanol. Growth performance, immune responses, intestinal morphology, and antioxidant enzymes were assessed in both challenged and non-challenged groups. A significant interaction between challenged and non-challenged groups for growth performance was observed so that weight gain (WG) and feed intake (FI) were significantly higher and feed conversion ratio (FCR) were significantly lower in WP with ethanol, WPC-no ethanol and no WP-no ethanol groups in comparison to other groups (P< 0.05). Intestinal morphology, humoral responses, and heterophil to lymphocyte ratio (H/L) were not affected by WP sources. Cellular immunity responses were significantly lower in no WP with ethanol and WP with ethanol groups in comparison to those of other groups after 48 h of phytohemagglutinin-P (PHA-P) injection. Ethanol challenge not only decreased villus width and liver antioxidant enzymes but also increased levels of malondialdehyde (MDA) and alanine aminotransferase (ALT) activities. Dietary inclusion of WP improved growth performance. The inclusion of WP and WPC increased levels of liver antioxidant enzymes and decreased MDA and ALT activities. It can be recommended to use WP in order to improve the growth performance and liver antioxidant enzymes in broiler chickens challenged with ethanol as liver peroxidases.

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