Increased dietary nutrient density did not restore growth performance in broiler chickens offered diets with high canola inclusion

Feed intake reduction is one of the key challenges in diets formulated with higher inclusions of canola products for broiler chickens. Increasing dietary nutrient densities was proposed to compensate for nutrient losses caused by decreased feed intake. Hence, this study investigated whether increasing amino acid and energy density in diets with higher inclusions of canola products restores growth performance in straight-run Ross 308 broiler chickens. The study included four dietary treatments: a typical wheat-soybean meal-based control diet (T1), a diet with high inclusions of canola products at 15, 20, 25, 30% in starter, grower finisher and withdrawal diets, respectively (T2), and two diets (T3 and T4) with higher nutrient densities compared to T2. In T3 and T4, nutrient densities were progressively increased across phases, with T3 increasing by 1.5% to 3.0% and T4 increasing by 3.0% to 6.0%. Body weight gain (P < 0.001), feed intake (P < 0.001), FCR (P = 0.003), and body weight corrected FCR at 2.5 kg (P = 0.007) were influenced by the dietary treatment from 0 to 42 days post-hatch. Including high levels of canola product depressed feed intake by 7.5% (4854 versus 4490 g/bird) and weight gain by 7.6% (3301 versus 3049 g/bird); increased weight-corrected FCR from 1.485 to 1.538 g/g compared to control diets (T1). Moderate increase in nutrient density (T3) did not alter growth performance in the diet containing high canola product inclusion but the further increase of nutrient density (T4) depressed feed intake to 4207 g/bird. Feed intakes were positively correlated to pellet durability indices (PDI) in the grower (r = 0.700, P < 0.001), finisher (r = 0.700, P < 0.001), and withdrawal phases (r = 0.656, P = 0.001). Nevertheless, higher inclusions of canola products significantly decreased the cost of feed per bird (P < 0.001) and cost of feed per kg of BW (P < 0.001) but increased the estimated age to reach 2.5 kg of body weight (P < 0.001). Subsequently, increasing nutrient densities in canola product-based diets increased the cost of feed per kg of birds (P < 0.001). In conclusion, increasing nutrient density in canola-based diets did not restore growth performance in broiler chickens offered diets containing higher canola inclusion rate.