Effect of enzyme supplementation and acidification of diets on nutrient digestibility and growth performance of broiler chicks

Two experiments were conducted to examine the effects of α-galactosidase supplementation and acidification of diets on nutrient digestibility and growth performance of broiler chicks. In experiment 1, dietary treatments consisted of feeding a low-energy basal diet (2.74 Mcal of ME/kg) alone, the basal diet supplemented with 1,724 units of α-galactosidase per kg, the basal diet supplemented with 2% citric acid, or the basal diet supplemented with both. α-Galactosidase significantly increased feed intake, weight gain, AME_n of the diets, and retention of CP and neutral detergent fiber (NDF) (P < 0.05). Citric acid significantly increased the retention of DM, CP, and NDF, but decreased feed intake and weight gain. The greatest values for DM and NDF retention and for AME_n were obtained with the combination of α-galactosidase plus citric acid. In experiment 2, chicks were fed diets with 2 levels of energy (2.74 or 3.11 Mcal/kg), 2 levels of citric acid (0 or 1.5%), and 2 levels of α-galactosidase (0 or 1,724 units/kg) in a 2 × 2 × 2 factorial arrangement of treatments. α-Galactosidase significantly increased the reducing sugar concentration in the crop content, whereas citric acid decreased the pH and increased the reducing sugar concentration in the crop content. Citric acid decreased the gain to feed ratio in the absence but not in the presence of α-galactosidase. The data from these studies indicate that acidification of diet improves the efficacy of α-galactosidase.