The effect of protease supplementation in broiler chicken diets containing maize from different batches on growth performance and nutrient digestibility

Abstract

Maize is the primary energy source in poultry diets. Nutritional and physical traits related to maize composition can affect nutrient utilization, as well as the efficacy of exogenous enzymes. A study was conducted to evaluate the effect of maize from different batches and protease supplementation on growth performance and ileal nutrient digestibility of broiler chickens from 1 to 40 days of age. A total of 1 920-day-old Ross 308 male chicks were assigned in a complete randomized design distributed into a 2 × 2 factorial arrangement comprising maize from two different batches (A and B) without and with protease (0 and 200 g/t), totaling 4 treatments and 12 replicates of 40 broiler chickens each. Experimental diets were divided into starter, grower I, grower II, and finisher phases. Both maize types were analyzed for nutritional composition, hardness, and structural differences in the starch granules via scanning electron microscopy. Feed intake, weight gain (WG), and feed conversion ratio (FCR) were evaluated. Ileal digesta was collected at 35 days to determine the apparent ileal digestibility (AID) of DM, CP, and ileal digestible energy (IDE). Hardness was higher in maize grains from batch A (P < 0.05), which may be associated with the denser and compact starch granules observed in electron microscopy. Broiler chickens fed maize from batch B and supplemented with protease showed greater WG and better FCR from 9 to 19 days (P < 0.05). From 1 to 40 days, birds fed the maize B diet had greater WG and lower FCR compared to those fed the maize A diet (P < 0.05). In the total period, protease supplementation reduced FCR (P < 0.01). No differences were found for AID of DM and CP, but broilers fed maize B diets had greater IDE (P < 0.05). In conclusion, although nutrient ileal digestibility was unaffected by treatments, the use of maize B led to superior growth performance and energy utilization due to its softer endosperm and starch composition, and protease supplementation reduced FCR and increased IDE regardless of maize batch.