Protease and Phytase Alleviate Digestive Limitations of Canola Seed in Broiler Chickens

BACKGROUND: While canola seed is a valuable protein and energy source in poultry nutrition, its use is often limited by antinutritional factors that impair nutrient utilisation and bird performance. OBJECTIVES: This study investigated the effects of phytase and protease enzymes in diets containing canola seed on performance, nutrient digestibility, digestive enzyme activity, intestinal morphology, ileal microbial populations, intestinal viscosity and tibia bone mineralisation in broiler chickens. METHODS: A total of 300 male Ross 308 one-day-old chicks were used in a completely randomised design with 5 treatments, 5 replicates and 12 chicks per replicate. The experimental treatments included: control: a corn-soybean meal-based control diet without canola seed; CS-10: a diet containing 10% canola seed; CS-PRO: a diet containing 10% canola seed supplemented with protease; CS-PHY: a diet containing 10% canola seed supplemented with phytase and CS-PRO-PHY: a diet containing 10% canola seed supplemented with a combination of protease and phytase. RESULTS: Feed intake and body weight gain were significantly higher in the control and CS-PRO-PHY treatments at different experimental periods compared to the CS-10 diet (P < 0.05). Apparent metabolisable energy and the digestibility of crude fibre and ash were higher in the control group and in broilers fed CS-PHY and CS-PRO-PHY compared with birds fed the CS-10 and CS-PRO diets (P < 0.05). At Day 10, amylase and lipase activity were highest in broilers fed the CS-PRO-PHY (P = 0.001). The villus height and villus height-to-crypt depth ratio on Days 10 and 42 were significantly higher in broilers fed the control diet, the CS-PRO-PHY and CS-PHY compared to the CS-10 (P < 0.01). At Day 10, Lactobacillus populations were highest in broilers fed the CS-PRO-PHY and the control diet, and lowest in the CS-10 (P = 0.03). Duodenal and jejunal digesta viscosity was significantly higher in broilers fed the CS-10 diet compared with all other treatments (P < 0.01). Tibia weight, length and weight-to-length index of the bone in the CS-PRO-PHY treatment were significantly greater than those in the CS-10 and CS-PRO treatments (P < 0.05). Moreover, bone strength in the control, CS-PRO-PHY and CS-PHY treatments was higher than in the CS-10 treatment (P = 0.034). CONCLUSIONS: Supplementation of broiler diets containing 10% canola seed with protease and phytase, particularly in combination, effectively mitigated the negative effects of canola on nutrient digestibility, intestinal morphology, microbial balance, digesta viscosity and bone quality, leading to restoration of performance.