An experiment was conducted to evaluate the effects of dietary soy hulls (SH) addition on growth performance, digestive traits, and apparent ileal digestibility of dry matter, nitrogen and phosphorus in broiler chickens. Ross 308, male broilers (n = 224) were assigned to one of four diets including 0, 20, 40, or 60 g/kg SH, with 8 replications per treatment from 0 to 21 d of age in a completely randomized design. Soy hulls was added to corn-soybean meal-fish meal-corn gluten meal-based basal diet at the expense of sepiolite. Chromic oxide was used as an indigestible marker to determine apparent ileal digestibility. Data were subjected to orthogonal contrasts using general linear model procedure of SAS. Growth performance and small intestine weight and length, and gizzard content pH were not affected (P > 0.05) by increasing levels of dietary SH. Increasing the dietary SH level resulted in a linear increase (P < 0.01) in absolute empty gizzard weight. Relative gizzard weight was higher (P < 0.05) in birds fed on 60 g/kg SH diet compared to birds fed on 40 g/kg SH diet. Apparent ileal digestibility of nitrogen was not affected (P > 0.05) by dietary SH inclusion. However, apparent ileal digestibility of dry matter and phosphorus increased linearly (P < 0.01) with increasing dietary SH levels.
In conclusion, the inclusion of SH in a corn-soybean meal-fish meal-corn gluten meal-based diet improved ileal digestibility of dry matter and phosphorus and increased gizzard weight without affecting relative weight and length of small intestine and growth performance of broilers at 21 d of age. Thus, these findings indicate that dietary SH inclusion up to 6% may be beneficial for improving phosphorus digestibility without adversely affecting growth performance of broilers at 21 d of age.