Influence of tallow and calcium concentrations on the performance and energy and nutrient utilization in broiler starters.

The influence of tallow and Ca concentrations on the performance, apparent ileal digestibility, and total tract retention of N, Ca, P, and AME in broiler starter diets fed corn-soy-based diets was examined. The experimental design was a 3 × 3 factorial arrangement of treatments evaluating 3 inclusion levels of tallow (0, 40, and 80 g/kg) and 3 dietary concentrations of Ca (7, 10, and 13 g/kg). Nine treatment diets were formulated to meet the requirements for major nutrients for broiler starters, except for AME and Ca concentrations. The results showed that increasing tallow inclusion increased (P < 0.001) the weight gain and lowered (P < 0.001) the feed to gain. Increasing dietary Ca concentrations decreased (P < 0.001) the weight gain. Birds fed diets containing 7 g/kg of Ca had similar (P > 0.05) feed to gain to 10 g/kg of Ca but lower (P < 0.05) than that of 13 g/kg of Ca. In diets with no tallow, increasing Ca concentrations decreased (P < 0.05) feed intake, whereas diets with 40 and 80 g/kg of tallow containing 13 g/kg of Ca showed lower (P < 0.05) feed intake than those of 7 and 10 g/kg of Ca. Diets supplemented with 40 and 80 g/kg of tallow containing 7 g/kg of Ca showed the lowest (P < 0.05) excreta soap content. Total tract retention of fat was higher (P < 0.001) in diets with 40 g/kg of tallow compared with those with 0 and 80 g/kg of tallow. Birds fed diets containing 7 g/kg of Ca had similar (P > 0.05) fat retention to that of 10 g/kg of Ca, but higher (P < 0.05) than that of 13 g/kg of Ca. Calcium retention decreased (P < 0.001) with increasing Ca concentrations. Diets containing 13 g/kg of Ca had the lowest (P < 0.01) P retention. Diets with no inclusion of tallow containing 7 g/kg of Ca had higher (P < 0.05) N retention than that of 13 g/kg of Ca, but similar to 10 g/kg of Ca, whereas in 40 g/kg of tallow diets, 7 g/kg of Ca had the highest (P < 0.05) N retention. Increasing fat inclusion increased (P < 0.001) the soap content in ileal digesta. Diets with 40 g/kg of tallow had the highest ileal digestibility of fat (P < 0.001) and N (P < 0.01). Increasing inclusion of fat decreased (P < 0.001) ileal Ca digestibility. Diets containing 7 g/kg of Ca showed the highest ileal digestibility of fat (P < 0.01), N (P < 0.01), and P (P < 0.001). Birds fed diets containing 13 g/kg of Ca had higher ileal digestibility of Ca (P < 0.001) than those fed 7 and 10 g/kg of Ca diets. Overall, present data showed that the total tract retention and ileal digestibility of fat were higher with supplementation of 40 g/kg of tallow compared with those of 0 and 80 g/kg of tallow. High dietary Ca concentrations adversely affected the performance and the utilization of energy, N, Ca, and P in broiler starters.