497 Amylase supplementation influences nutrient digestibility regardless of corn type in broiler chicken diets

Abstract

Abstract Corn is the primary energy supply in the broiler chicken diet. Physical and nutritional characteristics related to corn endosperm can affect nutrient utilization, as well as the inclusion of exogenous enzymes. This study aimed to evaluate two different corn types classified according to endosperm traits in diets for broiler chickens supplemented or not with amylase. Male broiler chickens (n = 360; 1-d old Cobb 500) were allocated in metabolic battery cages and randomly assigned in a 2 x 2 factorial arrangement (2 corn types; 2 amylase doses: 0 and 90 g/t of diet). A hardness test was performed to categorize and classify each corn type according to breakage force. Corn endosperms were assessed through scanning electron microscopy to investigate structure variations of starch granules. From 19 to 21 d, excreta samples were collected to estimate apparent total tract retention (ATTR) of nutrients and apparent metabolizable energy (AME). On d 26, ileal digesta content was collected to determine apparent ileal nutrients digestibility (AID) and ileal digestible energy (IDE). Data were analyzed using the Student t-test for hardness test (P < 0.05). The Tukey test was performed with a significance declared of 5% to compare the averages obtained for ATTR and AID using the GLM procedure on R Software. Differences were observed in the hardness test (P < 0.05), which classified each corn type either as hard (217 N) or soft (166 N; Table 1). The SEM highlighted structural variations between the floury and vitreous endosperm of each corn. In soft corn, starch granules were more dispersed in the floury endosperm, with a less dense distribution observed in the vitreous endosperm compared with hard corn (Figure 1). However, hard corn exhibited a more compact starch granules distribution in both floury and vitreous endosperm. No differences were observed (P > 0.05) in ATTR of dry matter, crude protein, or AME attributed to corn type, but amylase supplementation improved ATTR of dry matter (P = 0.015) and crude protein (P = 0.020; Table 2). On AID, corn type affected (P = 0.041) dry matter coefficient, and amylase supplementation significantly improved dry matter (P = 0.019), crude protein ileal digestibility (P = 0.012), and IDE (P = 0.018). No interactions between corn type and amylase supplementation were observed (P > 0.05). These findings demonstrated that amylase supplemented in broiler diets impacts nutrient utilization regardless of the corn type used.