Influence of dietary glutamine supplementation on performance, biochemical indices and enzyme activities in broilers with cold-induced ascites

Abstract

This study was conducted to investigate the effects of dietary glutamine supplementation on performance and biochemical indices of broilers with cold-induced ascites. A total of 240 1-day-old male broiler chicks (Ross 308) were randomly allotted to three treatment groups, with four replicate pens per treatment and 20 birds per pen. The control birds were kept in a thermoneutral chamber and fed a basal diet, whereas the other two experimental groups were kept in a cold chamber to induce ascites and fed the basal diet supplemented with either 0 or 100 mg of glutamine/kg. The cold-treated birds consumed less (P < 0.05) feed and had lower (P < 0.05) weight gain compared with the control birds. Dietary glutamine supplementation had no effect (P > 0.05) on broiler performance. The cold-treated birds had higher (P < 0.05) right ventricle to total ventricle ratio and mortality due to ascites compared with the control birds. However, mortality due to ascites and right ventricle to total ventricle ratio was reduced (P < 0.05) by dietary glutamine supplementation. The cold-treated birds had higher (P < 0.05) red blood cell counts, haematocrit percentage and haemoglobin concentration compared with the control birds at 21 and 42 days of age. The activities of plasma lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were increased (P < 0.05) in cold-treated birds compared with the control birds at 42 days of age, but dietary glutamine supplementation reduced (P < 0.05) the activities of alanine aminotransferase and aspartate aminotransferase near to the control levels. The plasma and liver glutathione peroxidase activities were increased (P < 0.05) in cold-treated birds compared with the control birds at 21 and 42 days of age, whereas the reverse was true for malondialdehyde concentrations. The glutathione peroxidase activity was increased (P < 0.05), whereas the malondialdehyde concentration was decreased (P < 0.05) by dietary glutamine supplementation compared with the cold-treated birds at 42 days of age. The results indicated that the beneficial effect of glutamine is probably related to its ability to maintain near to normal free radical scavenging enzymes and the level of glutathione peroxidase bioactivity, thereby protecting cell membranes from oxidative damage via decreased lipid peroxidation.