Response of broiler chickens to processed soy protein product when offered at different inclusion levels in mash or crumbled prestarter diets

This study investigated the effects of varying levels (0, 50, and 100 g/kg) of a processed soy protein product (PSP), fed to chicks in mash or crumbled form up to 10 d posthatch on the gross performance, carcass quality, nutrient digestibility and digestive enzyme activities in broiler chickens. A total of 324 Ross 308 male day-old broiler chicks were used in 6 replicates per group, with 9 birds per replicate. Between hatch and 24 d, birds fed crumbled diets had higher (P < 0.05) body weight gain and feed intake than those fed mash diets, with the exception of those fed control mash diet. There was no significant effect of feed form, PSP levels in diets or their interactions on the ileal digestibility of nutrients. However, the total tract digestibility of crude protein and gross energy decreased (P < 0.05) with increasing PSP inclusion level. Increasing levels of PSP in diets increased (P < 0.001) tissue protein content at 24 d of age. Also, sucrase activity of broiler chickens fed on crumbled diets was significantly (P < 0.009) higher than was observed in mash-fed birds. Feed form is an important factor when processed soy protein is supplemented in prestarter diet and may improve growth and development of digestive functions later in the life of the birds.