The non-mineral nutritional impact of phytate in canola meal fed to broiler chicks

Abstract

Three experiments were conducted to study the effect of in vitro hydrolysis of phytate on the nutritional value of canola meal for broiler chickens. In experiment 1 canola meal was incubated (1:2 meal:H 2O; pH 5.0; 50°C) for 1.5 h with purified or crude phytase (Natuphos ®), or without enzyme addition. Phytase addition hydrolysed 72–73% of meal phytate but neither purified nor crude phytase improved broiler performance. Experiment 2 was designed to study the negative but non-significant effect of meal pre-treatment on the performance of broiler chickens noted in experiment 1. Untreated and four pre-treated meals were included in broiler diets. Pre-treatments consisted of water incubation (1:2 meal:H 2O; pH 5.8; 50°C; 1.5 h), acid incubation (pH 5.0), acid incubation followed by neutralisation with NaOH, and acid incubation followed by the use of additional dietary limestone to balance the anionic contribution of the acid treatment. Dietary treatment did not significantly affect broiler performance. The objectives of experiment 3 were to study the effect of total phytate removal in canola meal on broiler performance. Treatments included canola meal and five pre-treated meals: water incubation, acid incubation, acid incubation followed by neutralisation with NaOH, and the latter treatment using either purified or crude phytase during incubation. Meals were mixed in a ratio of 1:2 (meal:H 2O) and incubated for 23 h at 50°C. Pre-treatment with acid followed by neutralisation with NaOH reduced meal apparent metabolisable energy (AME n) and amino acid availability in comparison to the untreated control. Both purified and crude phytase improved AME n but only purified phytase improved amino acid availability. Broiler growth was unaffected by the elimination of phytate. Phytase addition improved feed to gain ratio with the effect of crude phytase being significant ( P<0.05).