RESUMO Objetivou-se determinar a digestibilidade ileal estandardizada dos aminoácidos (SIAAD) do farelo de soja (FS), milho + FS, trigo + FS e uma dieta livre de proteína (PFD) com fitase. Um total de 672 pintos machos (493±10g), Cobb 500, foi distribuído em um delineamento inteiramente ao acaso, com 12 tratamentos (PFD, PFD + FS, PFD + milho + FS e PFD + trigo + FS, suplementados com 0, 500 e 1000 FTU), oito repetições e sete aves por gaiola, no período de 14 a 23 dias. A suplementação de fitase em 500 FTU aumentou o SIAAD da metionina do FS (P<0,05) e da treonina do milho + FS (P<0,05). Não houve efeito significativo (P>0,05) para o SIAAD de metionina, arginina e histidina no trigo + farelo de soja à medida que os níveis de fitase aumentaram. No entanto, o SIAAD de lisina, treonina, isoleucina, fenilalanina, valina, cistina, alanina, ácido aspártico, ácido glutâmico, glicina, serina e tirosina diferiu (P<0,05). Em geral, a SIAAD do FS, milho + FS e trigo + FS foi de 90,32, 88,65 e 83,97% sem a suplementação de fitase (0 FTU); 91,31, 88,81 e 88,36% (500 FTU); e 91,36, 87,09 e 87,87% (1000 FTU). Em conclusão, a eficácia da suplementação com fitase para aumentar a SIAAD varia de acordo com o alimento e o nível de suplementação.

ABSTRACT The objective was to determine the standardized ileal amino acid digestibility (SIAAD) in soybean meal (SBM), corn + SBM, wheat + SBM and a protein free diet (PFD) associated with phytase. A total of 672 Cobb 500 (493±10g) male chicks were distributed in a completely randomized design with twelve treatments (PFD, PFD + SBM, PFD + corn + SBM and PFD + wheat + SBM, supplemented with 0, 500 and 1000 FTU), eight replicates and seven birds per cage from 14 to 23 days. Phytase supplementation at 500 FTU increased the SIAAD of methionine in SBM (P<0.05) and threonine in corn + SBM (P<0.05). There was no significant effect (P>0.05) for the SIAAD of methionine, arginine and histidine in wheat + SBM as the phytase supplementation. However, the SIAAD of lysine, threonine, isoleucine, phenylalanine, valine, cystine, alanine, aspartic acid, glutamic acid, glycine, serine and tyrosine differed (P<0.05). In general, the SIAAD for SBM, corn + SBM and wheat + SBM are 90.32, 88.65 and 83.97% (0 FTU); 91.31, 88.81 and 88.36% (500 FTU); and 91.36, 87.09 and 87.87% (1000 FTU). In conclusion, the efficacy of phytase for improve the SIAAD vary according to the feedstuff and level of supplementation.

ABSTRACT This study aimed to evaluate the effects of different exogenous protease and carbohydrase in broiler diets on the nitrogen-corrected apparent metabolizable energy (AMEn) and standardized ileal amino acid digestibility (SIAAD) of soybean meals (SBM) in two Brazilian regions (Minas Gerais-MG and Rio Grande do Sul-RS). The total excreta collection of 528 14-d-old chicks was used to determine AMEn in a completely randomized design in a 2 (SBM MG and RS) x 5 (enzyme A, B, C, D and basal diet) + 1 (reference diet, RD) factorial arrangement, totaling 11 treatments, 8 repetitions, and 6 birds per experimental unit. Two experimental treatments (T1 and T6) without enzyme supplementation formulated with SBM MG and RS were used as negative control (NC). The RD without the inclusion of SBM MG and RS was used to correct the nitrogen balance. To determine the SIAAD, ileal content was collected from of broilers and the same experimental design and treatments of the previous trial were used except for the RD, which was replaced with a nitrogen-free diet (NFD) to quantify the excretion of endogenous amino acids. Soybean meal from MG showed the highest levels (p<0.05) of AME and AMEn (3,188 kcal/kg and 2,700 kcal/kg, respectively) in comparison to SBM RS (3,121 kcal/kg and 2,549 kcal/kg, respectively) and, when supplemented with the exogenous enzyme C, also improved the SIAAD (p<0.05), as compared to other enzymes.

ABSTRACT The objective was to evaluate the effect of dietary 25-hydroxycholecalciferol (25(OH)D3) or vitamin D3 (VitD3) and different total calcium (Ca) levels on the performance, carcass characteristics, blood, enzymatic, and bone biochemistry of broilers reared under heat stress between 1 and 42 days of age. A total of 504 male, Cobb 500, broiler chickens were distributed in a completely randomized design in a 2 × 4 factorial arrangement (VitD3 or 25(OH)D3 × four Ca levels (100, 90, 80 and 70% of the recommendations of Rostagno et al. (2011)), eight treatments, seven replicates and nine broilers per cage. Feed intake and feed conversion ratio did not (p>0.05) vary when levels of Ca were reduced and vitamin D3 sources were supplemented in the diets from 1 to 21 days for broilers chickens. 25 (OH)D3 increased weight gain results (p<0.05). From 1 to 42 d, no differences (p>0.05) were observed on performance, carcass yields and meat quality, bone deposition of Ca and P, and alkaline phosphatase concentration. Higher serum (p<0.05) concentrations of Ca and P were found in broilers fed with 25(OH)D3. The replacement of VitD3 with 25(OH)D3 and the Ca reduction of 30% in diets did not negatively affect performance, carcass characteristics, and Ca and P deposition in the tibia of broilers at 42 days of age, under heat stress.

ABSTRACT This study aimed to evaluate the effect of different reductions in digestible amino acids content (lysine, methionine, and threonine), according to two nutritional requirements in corn, soybean meal, and meat and bone meal based diets, with protease supplementation, on performance parameters and carcass characteristics. A total of 1080 day-old chicks, male, Cobb 500, were allotted to a completely randomized design, in a factorial arrangement 3 x 2, three reductions in digestible amino acids content (lysine, methionine, and threonine) and two nutritional requirements (Rostagno et al. 2005 and Cobb-Vantress Guidelines 2008), and all diets were supplemented with protease (200 ppm) with 6 replicates of 30 birds per pen. There was no significant interaction (p<0.05) between digestible amino acid reductions and both nutritional requirements for the performance variables and carcass yield and cuts. There was an effect of amino acid reduction and protease supplementation only on slaughter weight (p<0.05). Broilers fed according to the nutritional requirements of Rostagno et al. (2005) showed better (p<0.05) performance when compared to broilers fed as specified by the nutritional requirements of Cobb-Vantress (2008) with no significant differences in carcass characteristics. Protease supplementation of corn, soybean meal, and meat and bone meal based diets allows a reduction in the inclusion of crystalline amino acids (lysine, methionine, and threonine).