Leucina e valina em dietas de baixa proteína para frangos de corte

• Autor(a) principal: Ospina Rojas, Iván Camilo
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/1580
• topic: Aminoácidos de cadeia ramificada; Nutrição animal; Corpo cetônico; Frangos de corte; Desempenho; Expressão gênica; Amônia; Desempenho de frangos de corte; mTOR; Brasil.; Ammonia; Branched chain amino acid; Gene expression; Ketone body; mTOR; Poultry performance; Brazil.; Ciências Agrárias; Zootecnia

Five experiments were performed to study the requirements and interactions between leucine and valine digestible in low-CP diets, and their effects on performance, serum and bone parameters, litter characteristics and mRNA expression of the genes mTOR, S6K1, eIF4E 4EBP1 and eEF2, and fiber diameter of the pectoralis major muscle of broiler chickens. In the experiments II (1-21 days), III (21-42 days), IV (1-21 days) and V (21-42 days), a total of 1,500 1-day-old Cobb-Vantress® male broilers were distributed in a completely randomized experimental design in a 5x5 factorial arrangement with 25 treatments with three replicate pens of 20 birds each. Digestible leucine and valine levels ranged from 1.00 up to 1.96%, and 0.60 up to 1.20% for the starter phase, while for the grower phase ranged from 1.00 up to 1.80%, and 0.52 up to 1.12%, respectively. In the experiment III (1-21 days), a total of 540 1-day-old Cobb-Vantress® male broilers were distributed in a completely randomized experimental design in a 3x3 factorial arrangement with 9 treatments with three replicate pens of 20 birds each. Treatments consisted of three dietary levels of digestible leucine (1.00; 1.48 and 1.96 %) and three levels of digestible valine (0.60; 0.90 and 1.20 %). In the experiment I (starter phase), at 21 days interactions (P < 0.05) were observed between dietary leucine and valine levels for feed intake and feed:gain ratio. There was a quadratic effect (P < 0.01) of digestible leucine and valine levels on BW gain, with an optimization level of 1.28 and 0.92%, respectively. Valine and leucine supplementation did not affect (P > 0.05) the serum concentrations of uric acid, triglycerides, β-hydroxybutyrate, total protein and albumin of the birds. Serum levels of ammonia increased linearly (P < 0.05) with increasing levels of digestible leucine. However, valine supplementation reduced (P < 0.05) ammonia serum concentrations. Serum levels of glucose decreased and increased linearly (P ≤ 0.06) with increasing levels of digestible leucine and valine, respectively. In the experiment II (grower phase), at 42 days interactions (P < 0.05) were observed between dietary leucine and valine levels for feed intake and BW gain. There was a quadratic effect (P < 0.01) of digestible leucine and valine levels on feed:gain ratio, with an optimization level of 1.19 and 0.86%, respectively. Leucine supplementation decreased (P < 0.05) serum concentrations of triglycerides and ketone bodies, but increased levels of serum ammonia. Valine supplementation resulted in quadratic reduction (P ≤ 0.07) of the serum ammonia. Breast yield was maximized at the level of 1.13% leucine, while the leg yield was optimized at the level of 0.78% valine. Abdominal fat decreased linearly (P < 0.05) with increasing dietary levels of digestible leucine and valine. In the experiment III (starter phase), there was no interaction (P > 0.05) between the levels of leucine and valine on mRNA expression of the studied genes in chick pectoral muscle. Leucine supplementation increased (P < 0.05) mRNA expression of mTOR and S6K1, however, did not affect (P > 0.05) mRNA expression of eIF4E 4EBP1 and eEF2 in pectoralis major muscle. Dietary valine did not affect (P > 0.05) the expression of the studied genes. In the experiment IV (1-21 days) and V (21-42 days), there was no interaction (P > 0.05) between the levels of leucine and valine on the fiber diameter of the pectoralis major muscle of the poultry at 21 and 42 days of age. Leucine supplementation decreased (P < 0.05) the hypertrophic zone of the growth plate of broilers at 21 days. There was an interaction (P > 0.05) between digestible levels of leucine and valine on tibia bone strength of broilers at 21 days, but not at 42 days of age (P > 0.05). Based on feed:gain ratio, digestible leucine and valine requirements were 1.29 and 0.91%, respectively, in low-CP diets for male broilers in the starter phase, while for the grower phase, the requirement for leucine and digestible valine were 1.19 and 0.86%. Leucine supplementation may stimulate mRNA expression of mTOR and S6K1 in pectoral muscle of broilers during the starter phase. Appropriate levels of leucine and valine can be essential in the formation of bone structure, resulting in increased resistance to bones in broilers during the period from 1-21 days of age.