<b>Threonine-lysine ratio on the requirements of digestible lysine in diets for broilers

Abstract

ABSTRACT.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.Keywords: amino-acid, lysine, ideal protein, threonine.Relação treonina: lisina sobre a exigência de lisina digestível em dietas para frangos de corte RESUMO. 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.Palavras-chave: aminoácido, lisina, proteína ideal, treonina.

Digestible Threonine to Lysine Ratios for Meat-Type Quails

“…Rossoni et al (2008) also reported a negative effect of excessive dietary threonine on pig feed intake and fat deposition. Ospina-Roja et al (2014) attributed the worse performance observed in 22-to 42-d-old broilers fed digestible Thr:Lys ratios higher than 57% to impaired protein synthesis caused by dietary amino-acid imbalance. According to those authors, the deamination of threonine excess relative the other amino acid into uric acid requires energy, which consequently impair animal performance.…”

Production performance and plasma metabolite concentrations of broiler chickens fed low crude protein diets differing in Thr and Gly

“…Threonine has been extensively investigated and reviewed since feed grade l -Thr has been available worldwide. Researchers have recently updated the Thr requirements and recommended higher dietary levels than previously suggested for modern broilers, especially in the starter phase ( Dozier et al., 2015 ; Mehri et al., 2014 ; Ospina-Rojas et al., 2014 ).…”