Effect of maize endosperm hardness, drying temperature and microbial enzyme supplementation on the performance of broiler chickens

Abstract

This study was conducted to determine the influence of maize endosperm type (soft or vitreous), drying temperature (60, 100, 140°C), and enzyme addition (no enzyme or phytase + xylanase) on broiler chicken growth, amino acid availability, and phytate phosphorus hydrolysis. One-day-old Ross-308 broiler chicks (total 1200) were allotted to floor pens with a randomised complete block design (2 × 3 × 2). Diets were formulated to be marginally deficient in Lys, total sulfur amino acids, calcium, and nonphytate phosphorus. A positive effect (P < 0.05) of enzyme addition on chicken bodyweight gain to day 35 was observed (1884 vs 1940 g). Bodyweight gains and feed conversion ratios (FCR) were linearly depressed when drying temperature was increased. Chickens fed vitreous maize were characterised by lower bodyweight gain (1932 vs 1893 g; P < 0.05) and higher FCR (1.796 vs 1.840g : g; P < 0.05). There were no interactions between any of the main effects for overall performance metrics. The use of phytase improved phytic acid digestibility (0.302 vs 0.389; P < 0.05) but phytic acid digestibility was unaffected (P > 0.05) by drying temperature or hardness. The highest drying temperature had a negative effect on amino acids digestibility (P < 0.05). The use of phytase and xylanase improved amino acid apparent ileal digestibility (P < 0.05), except for Cys, Met, and Phe. Results from this study show that drying temperature and vitreousness of maize influence the nutritional value of this grain for broilers. Part of the beneficial effect of the addition of phytase + xylanase to diets with overheated maize for poultry appears to be mediated through an improvement in amino acid availability.