The effect of different dietary levels of canola meal on growth performance, nutrient digestibility, and gut morphology of broiler chickens.

This study evaluated the effects of different levels of canola meal in broiler diets on growth performance, nutrient digestibility, and duodenal morphometry. A total of 320 one-day-old Cobb broilers were used in a 35-d experiment. A completely randomized design with 5 levels of canola meal (0, 10, 20, 30, and 40%) as a substitute for soybean meal was used with 8 replicates of 8 birds each. The basal diets were formulated based on corn and soybean meal to meet nutrient requirements of broiler chickens. The levels of canola meal were evaluated with a polynomial regression at 5% of significance. Weight gain and average BW showed a quadratic response (P = 0.03 and P = 0.04, respectively), decreasing with the addition of 40% canola meal. The apparent nutrient digestibility of DM (P < 0.0001), CP (P < 0.0001), and nitrogen-free extract (P < 0.0001) decreased linearly with increased levels of canola meal. A quadratic effect was observed for villus height (P = 0.003), decreasing up to a 20% inclusion of canola meal in the diet and increasing beyond that level. In conclusion, canola meal can be added up to 16.7% in diets for broilers without affecting the key variables of growth performance. It can be added up to 20% with no negative effect on the CP digestibility, but there was a linear decrease in the digestibility of DM and nitrogen-free extract with increased inclusion of canola meal. Additionally, a quadratic response to canola was observed for villus height with a maximum at 23.6% canola meal.