Abstract
A total of 450, one-day-old broiler chicks (Ross 308) were used to examine the impact of three poultry by-product meal (PMB) levels (0, 2, and 4 %), and three wheat levels (0, 10, and 20 %) on physical pellet quality (PPQ), growth performance, and carcass features of broilers during starter, grower and finisher periods. The results of the current study demonstrated that during the starter phase, the inclusion of 2 % and 4 % PBM significantly (P ˂ 0.01) reduced PDI (Pellet Durability Index) in wheat-free diets. However, this reduction was not observed in diets supplemented with 10 % and 20 % wheat. During the growth phase, the inclusion of 2 % and 4 % PBM resulted in a reduction (P ˂ 0.01) in PDI in wheat-free diets. In contrast, diets containing 20 % wheat showed an increase in PDI by adding 2 % and 4 % PBM. During the finisher phase, including of 4 % PBM led to an increase (P ˂ 0.01) in PDI in wheat-free diets. Conversely, in diets containing 10 % and 20 % wheat, PDI decreased by adding 4 % PBM. In the starter diet, includingwheat resulted in a reduction (P ˂ 0.05) in pellet hardness. Additionally, during the growth and finisher phases, the inclusion of 2 % PBM reduced (P ˂ 0.01) PDI in wheat-free diets and diets containing 10 % wheat, respectively; however, this effect was not observed in diets containing 20 % wheat. Feed intake was influenced by the interaction effects of PBM and wheat levels, such that the addition of 10 % wheat to the diet without PBM led to an increase in feed intake compared to diets without wheat and with 0 % or 2 % PBM during the entire period of study (P < 0.05). Throughout the experimental period, no significant differences were observed in the average daily gain among the experimental groups (P ˃ 0.05). Additionally, the feed conversion ratio (FCR) in birds fed diets containing 2 % PBM showed improvement compared to those fed diets with 4 % PBM and was comparable to the control group (P < 0.05). Birds fed 20 % wheat had significantly (P < 0.05) the lowest abdominal fat. The findings of this study indicated that while the inclusion of 2 % PBM improved the FCR in broilers, it resulted in a decrease in PDI during both the starter and growth periods, as well as reduced pellet hardness in the growth phase for diets without wheat.