ABSTRACT An experiment with 23 diets was performed to evaluate the effect of digestible lysine (Lys), digestible methionine + cysteine (Met+Cys), and digestible threonine (Thr) on egg production of H&N Brown second-cycle laying hens (SCLH) for 20 weeks (92-111 weeks of age) in cages under environmental conditions. Body weight (BW), feed intake (FI), feed conversion ratio (FCR), egg weight (EW), number of hen-housed eggs, and livability were also evaluated during the experiment. Diets were formulated from a central composite design that combined five levels of Lys, Met+Cys, and Thr ranging from 727 to 1159, 662 to 1055, and 552 to 882 mg/kg, respectively. Egg production (EP) data were evaluated through three different modeling strategies: egg production models, multivariate polynomial models, and artificial neural networks (ANN). A cascade-forward neural network with log-sigmoid transfer function was selected as the best model according to goodness-of-fit statistics in both identification and validation data. One of the best scenarios for EP of H&N Brown SCLH under specific outdoor conditions was established at Lys, Met+Cys, and Thr levels of 1138, 1031, and 717 mg/hen·day, respectively. The ANN model may be an appropriate tool to study and predict EP of H&N Brown SCLH based on the combination of three different levels of essential digestible amino acids. The strategies included in this work may contribute to improving poultry performance based on modeling techniques to study other production parameters in terms of different nutritional requirements and productive conditions.

RESUMO. Este estudo foi realizado com o objetivo de avaliar a suplementação de probiótico em dietas à base de bolo de manteiga de carité - sheabuttercake (SBC) sobre as características de carcaça e índices hematológicos de frangos de corte. Foram utilizados 280 frangos de corte da linhagem Arbor acres, distribuídos em um delineamento inteiramente casualizado com sete tratamentos, quatro repetições e dez aves por repetição. Foi formulada uma dieta sem SBC nem probiótico e utilizada como dieta controle. As demais dietas experimentais continham 5, 10 e 15% de SBC e com (+) ou sem (-) a suplementação de probiótico. Os parâmetros de carcaça e o peso dos cortes nobres aumentaram (p < 0.05) nas aves que receberam as dietas com (+) SBC probiótico quando comparadas com o controle. O teor de gordura abdominal foi menor (p < 0.05) nas aves que receberam as dietas com (+) SBC-probiótico do que nas aves alimentas com a dieta controle ou com (-) SBC sem probiótico. Não foram observadas diferenças (p < 0.05) para o peso relativo dos órgãos, exceto para o peso do fígado e da bolsa cloacal. A quantidade de eritrócitos e hemoglobina foram maiores (p < 0.05) nas aves que receberam as dietas com (+) SBC-probiótico quando comparadas com o tratamento controle. A suplementação com probiótico em até 15% melhorou as características de carcaça e o peso relativo dos cortes nobres e órgãos sem nenhum efeito adverso nos parâmetros sanguíneos.

ABSTRACT. A 42-day study was conducted to investigate probiotic supplementation on shea butter cake (SBC) based diets of broilers on the carcass traits and haematological indices. A total of 280, 1-day old Arbor acres strain broiler chicks were divided into 7 dietary treatments with 4 replicates of 10 birds each in a completely randomized design. Diet 1 (control diet) has no SBC and probiotic supplementation while remaining 6 diets contained 5, 10, and 15% levels of SBC each with (+) or without (-) probiotic supplementation. The results showed that carcass parameters and prime cuts weights increased (p < 0.05) in birds fed probiotic-SBC diets compared to control diets. Abdominal fat content was lower (p < 0.05) in birds fed probiotic-SBC diets than those on control and non-probiotic SBC diets. Differences in relative organ weights among all treatments were non-significant (p > 0.05) except for liver and bursa weight. Packed cell volume and hemoglobin contents were higher (p < 0.05) in birds fed probiotic-SBC diets than the group without probiotic supplementation compared to those on control diet. In conclusion, supplementation of multi-strain probiotic improved carcass traits, prime cut-parts and relative organ weights without any adverse effect on the blood parameters up to 15% inclusion level.

This study was developed to evaluate the effect of the digestible valine:lysine ratio (dig Val:Lys) in the diet of 1 to 14-d-old broilers on performance, feathering, diameter and profile of muscle fibers. A total of 1,080 1-d-old Cobb 500 broilers were distributed in a completely randomized experimental design with five treatments and six replicates of 36 birds each. Treatments consisted of different dietary ratios of dig Val:Lys (66, 71, 76, 81 and 86 %) in the period between 1 and 14 d of age. The dig Val:Lys ratio did not influence (P>0.05) bird performance. Nevertheless, there was a positive linear effect (P<0.05) of dig Val:Lys ratio on back feather length and feathering score of the thigh and breast. The dig Val:Lys ratio had a quadratic effect (P<0.05) on the diameter of muscle fibers, with an estimated dig Val:Lys ratio of 76 %. The muscle fiber profile was not influenced (P>0.05) by the treatments. It was concluded that a Val:Lys ratio of 66 % is sufficient to maximize the performance of broilers from 1 to 14 d of age; however, a higher dig Val:Lys ratio (76 %) is needed to maximize muscle fiber growth.

El objetivo fue evaluar el efecto de la relación valina:lisina digestible (Val:Lys dig) en la dieta de pollos de engorda en el período de 1 a 14 días de edad sobre el comportamiento productivo, emplume, diámetro y perfil de fibras musculares. Se utilizaron 1,800 pollos de engorda Cobb de un día de edad, distribuidos en un diseño experimental completamente al azar con cinco tratamientos, seis repeticiones y 36 aves por unidad experimental. Los tratamientos consistieron de diferentes relaciones de Val:Lys dig (66, 71, 76, 81 y 86 %). La relación Val:Lys dig no afectó (P>0.05) el comportamiento productivo de las aves. Sin embargo, hubo efecto lineal positivo (P<0.05) de la relación Val:Lys dig en la longitud de las plumas del dorso y en la puntuación de emplume del muslo y pechuga. La relación Val:Lys dig resultó en efecto cuadrático (P<0.05) sobre el diámetro de las fibras musculares, siendo estimada una relación de 76 % de Val:Lys dig. El perfil de las fibras musculares no se afectó (P>0.05) por los tratamientos. Se concluye que la relación Val:Lys de 66 % es suficiente para maximizar el comportamiento productivo de pollos de engorda en la fase de 1 a 14 días, no obstante, una mayor relación de Val:Lys dig (76 %) es necesaria para maximizar el crecimiento de las fibras musculares.

Dois experimentos foram realizados com o objetivo de determinar a influência da relação treonina:lisina (Thr:Lys) sobre a exigência de lisina (Lys) digestível em dietas com baixa PB para frangos de corte na fase de crescimento. No primeiro experimento, foram utilizados 480 frangos de corte, machos da linhagem Cobb 500, distribuídos em um delineamento experimental inteiramente casualizado, com quatro relações de Thr:Lys (57,0; 60,5; 64,0 e 67,5%) e cinco repetições com 24 aves cada. Não foram observadas diferenças significativas no ganho de peso, consumo de ração, umidade de cama e rendimento de carcaça e de cortes. Entretanto, a conversão alimentar piorou conforme a relação Thr:Lys aumentou na dieta. No segundo experimento, foram utilizados 400 frangos de corte distribuídos em um delineamento experimental inteiramente casualizado, com quatro níveis de Lys digestível (1,005; 1,045; 1,085 e 1,125%) e quatro repetições com 25 aves cada. Não foram observadas diferenças significativas no desempenho, umidade de cama e rendimento de carcaça e de cortes. O nível de Lys de 1,005% e a relação de Thr:Lys de 57% foi suficiente para maximizar o desempenho e o rendimento de carcaça de frangos de corte na fase de crescimento alimentados com dietas baixas em PB.

Two experiments were performed to determine the influence of threonine-lysine (Thr:Lys) ratio on requirements of digestible lysine (Lys) in low crude protein diets for broilers in the growth phase. In the first experiment, a total of 480 Cobb 500 male broilers were distributed in a completely randomized experimental design with four dietary Thr:Lys ratio (57.0; 60.5; 64.0 and 67.5%) and with five replicates of 24 birds each. No significant differences were reported in weight gain, feed intake, poultry manure humidity, carcass and meat yields. However, the feed conversion was increased linearly as dietary Thr:Lys ratio was increased. In the second experiment, a total of 400 Cobb 500 male broilers were distributed in a completely randomized experimental design with four digestible Lys levels (1.005, 1.045, 1.085 and 1.125%), and with four replicates of 25 birds each. No significant differences were reported in performance, poultry litter humidity and carcass and meat yields. Lys levels of 1.005% and Thr:Lys at 57% were sufficient to maximize the performance and carcass yield of broilers during the growth phase when fed on low crude protein diets.