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This study aimed to assess the effect of preprocessing of corn and of physical form of diets on growth performance, carcass yield, and nutrient digestibility in broilers and also the influence of corn processing on pellet quality. A total of 1,080 male Cobb chicks from 1 to 35 D were evaluated. Birds were distributed according to a completely randomized design in a 3 × 2 factorial arrangement, with 3 types of corn processing (unprocessed, pelleted, or expanded), and 2 diet physical forms (mash or pelleted), totaling 6 treatments and 9 replicates with 20 birds. The data were submitted to ANOVA, and means were compared by Tukey's test ( P < 0.05). There was no interaction between the physical form and preprocessing of corn for any of the studied variables ( P > 0.05). The use of expanded corn in the diets before pelleting resulted in higher pellet durability index and lower amount of fines ( P < 0.05) when compared with unprocessed corn. Broilers fed pelleted diets had higher feed intake ( FI ) and weight gain ( WG ; P < 0.001), higher amounts of abdominal fat ( P < 0.05), and lower ileal digestible energy ( IDE , P = 0.05) than those fed mash. There was no effect of the feed form on nutrient digestibility ( P > 0.05). Broilers fed diets with unprocessed corn had higher FI when compared to those fed diets with expanded or pelleted corn ( P < 0.001). The use of pelleted corn resulted in lower WG than the other processing methods ( P < 0.01). The corn expansion process improved feed conversion ratio and adjusted feed conversion ratio ( P < 0.001). Inclusion of expanded corn improved the coefficient of apparent ileal digestibility of DM, CP, starch, and IDE ( P < 0.05) in comparison with unprocessed corn. It is concluded that pelleted diets improve broiler performance. The corn expansion can be used to improve physical quality of the diets and broilers growth performance and nutrient digestibility.

Enzymes benefit digestion and absorption of the ingredients and their addition to an animal-origin meal (AOM) can improve its nutritional quality. This research aimed to evaluate the effect of protease on nutrient digestibility, amino acids, and metabolism of AOM energy for broilers. Four hundred and eighty broiler chickens were distributed in a completely randomized design (4 × 2 factorial scheme), eight treatments, six replicates containing 10 birds/replicate. Treatments consisted of poultry viscera meal, swine viscera meal (SVM), bovine meat and bone meal, and basal diet; with and without protease addition. Two tests were performed. In the first test, the total excreta collection method was used with birds at 13 to 20 days of age and 25% of the reference feed was replaced by AOM. In the second test, a protein-free diet was administered to birds at 21 to 24 days of age and AOM replaced 25% of the starch. The inclusion of protease increased the apparent metabolizable energy corrected for nitrogen balance of SVM by 15.99% and the apparent metabolizable crude energy by 5.7%, and it also raised the coefficient of true ileal digestibility of the amino acids in the AOMs by 5.67% on average. The inclusion of protease improved the apparent metabolizable crude energy of AOMs, apparent metabolizable dry matter of bovine meat and bone meal, coefficient of true ileal digestibility of essential amino acids, and apparent metabolizable energy corrected for nitrogen balance of SVM. Dietary supplementation of protease may be a potential strategy to improve the digestibility of amino acids for broilers, a possibility of using animal-origin meals as a protein source of diets.

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