Níveis de lisina digestível e validação da proteína ideal em rações para frangos de corte

• Autor(a) principal: Oliveira, Will Pereira de
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1796
• topic: Aminoácido digestível; Aves; Desempenho; Digestible amino acids; Birds; Performance; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL

Four experiments were conducted with broiler chickens, two (experiments 1 and 2) to evaluate the effect of digestible lysine levels in diets with or without supplementation of industrial amino acids and two (experiments 3 and 4) to validate the relatios of digestible amino acids: Threonine, Valine, Isoleucine, Arginine and Tryptophan; with Lysine in the ideal protein for broilers under two thermal environments: thermoneutral and heat stress. In experiment 1, 1440 broilers of 8 to 21 days of age with average initial weight of 168.12g were distributed in a completely randomized experimental design (CRD), in a 5 x 2 factorial arrangement [(five digestible lysine levels: 1.00; 1.10; 1.20; 1.30 and 1.40% and two types of diet: diet with different corn and soybean meal ratios (C+SM) and diet supplemented with industrial amino acids (CP+AA)], eight replicates and 18 birds per replicate. Interaction effect was observed only on weight gain (WG) and fat deposition (FD) of birds. Lysine levels reduced feed intake (FI) linearly in both diets. The lysine levels of the C+SM diet effected weight gain (WG) and feed conversion (FC) quadratically; they improved up to the estimate levels of 1.30 and 1.40% lysine, respectively. In the CP+AA diet, lysine levels increased WG and improved FC linearly. Regardless of the type of diet, the protein deposition increased linearly, whereas fat deposition reduced linearly with increase in he lysine levels of the diets. The C+SM diet promoted smaller fat deposition in reation to the CP+AA diet. In experiment 2, 1280 broilers of 22 to 42 days of age with average initial weight of 787.5g were distributed in a CRD, in a 4 x 2 factorial arrangement (four digestible lysine levels: 0.90; 1.00; 1.10 and 1.20% and two types of diets, formulated by methodology similar to that of experiment 1), eight replicates and 20 birds per replicate. Interaction effect was observed on the performance and carcass parameters evaluated. In both diets, FC improved linearly with the increase in lysine levels. The lysine levels of the C+SM diet affected FI, WG, absolute weight (AW) of carcass, thigh, drumstick and yield (Y) of boneless breast, which increased linearly. However, AW and Y of abdominal fat (AF) reduced linearly with increase in the lysine levels of the C+SM diet. In birds fed the CP+AA diet, lysine levels reduced the drumstick Y linearly and affected boneless and boned breast Y, which reduced up to the estimate levels of 1.04 and 1.07% lysine, respectively. The excretion and retention of nitrogen increased linearly with lysine levels in the C+SM diet. In experiment 3, 336 male broilers of 22 to 42 days of age were distributed in a CRD with eight treatments (diets) [basal; five diets with ideal ratios with lysine: threonine (Thr), valine (Val), isoleucine (Ile), arginine (Arg), Tryptophan (Trp); ideal protein (IP); IP+glutamic acid+glycine (IP+Glu+Gly)], six replicates and seven birds per replicate, housed in airconditioned rooms. The air temperature (AT) and relative humidity (RU) of the rooms were 23.8±115°C and 69.8±5.59%. The calculated wet bulb globe temperature (WBGT) was 70.9±1.66. No effect of experimental diets was observed on FI, WG and FC. Likewise, AW and Y of AF presented the greatest value for the IP diet and the lowest value for the Thr diet. In experiment 4, the methodology applied was similar to that of experiment 3; however, the air-conditioned rooms were set to promote heat stress. The AT, RU and WBGT values obtained were 32.0±0.55°C, 66.9±5.63% and 82.7±0.87, respectively. Experimental diets did not affect FI, WG or FC. AW of carcass, bone and boneless breast, leg and AF, the same way carcass and boneless Y were not affected by experimental diets. The greater boned breast Y and the lower leg Y were originated by the IP+Glu+Gly diet. The IP diet promoted higher AF Y in comparison with the other diets. One can conclude that, for broilers in the phase of 8 to 21 days of age, the estimated levels of 1.30 and 1.40% digestible lysine in the C+SM diets, the 1.40% digestible lysine level in the diet promoted the best performance. For the phase of 22 to 42 days of age, the 1.20 and 0.90% lysine levels of diets C+SM and CP+AA, respectively, corresponded to lysine requirements for better performance. The ratios of amino acids threonine, tryptophan, arginine, valine and isoleucine with lysine at the 1.10% level on the digestible basis in ideal protein recommended by Rostagno et al. (2005) are adequate for broilers under thermoneutral and heat stress environments. In heat stress, supplementation with glutamic acid and glycine may improve carcass characteristics of broilers.