Effect of Dietary Ascorbic Acid on Performance and Immune Response of Heat Stressed Broiler Chicks

Abstract

A total of 112, day-old broiler chicks were reared under summer temperature of the Sudan (35-45°C) to study the effect of supplementation of ascorbic acid on the feed intake, Feed Conversion Ratio (FCR), weight gain, immune status and ratio of weight of bursa, thymus and spleen to body weight. Four level of ascorbic acid 0 (control), 150 (low level), 350 (moderate level) and 550 (high level) mg/kg were used from day 14-42 day. Birds fed low and moderate levels of ascorbic acid (150, 350 mg/kg) show high feed intake compared to those fed high level (550 mg/kg), which resulted in improvement in body weight and feed conversion ratio of the moderate and low levels. Dressing percentage was not affected by different level of ascorbic acid. Total white blood cells were reduced as the level of ascorbic acid was increased. Lymphocytes increased in birds fed moderate or high levels of ascorbic acid. Heterophils were decreased in the group fed the moderate level and high levels of ascorbic acid. Monocytes decreased in the groups fed the high level, However, basophils and esinophils were not affected by the different levels of ascorbic acid. The mean weight of lymphoid organs or the ratio of lymphoid organs to body weight was not affected by the different treatments. Antibody titer against Newcastle virus was increased in birds fed diets supplemented with different levels of ascorbic acid.