Avaliação de dietas formuladas com aminoácidos totais e digstíveis e estimativas do crescimento e da deposição de nutrientes em frangos de corte / Evaluation of diets based on total and digestible amino acids and estimates of growth and nutrients deposition in broiler chickens

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Three experiments were run with the objectives to determine the true digestibility coefficients (TDC) of crude protein (CP) and amino acids of feedstuffs, complete diets and of synthetic amino acids (SAA), both obtained by endogenous nutrients losses using protein free diet (PFD), PFD plus amino acids (PFD+AA), and enzyme-hydrolyzed casein (EHC) - Exp.1. To evaluated the performance of broiler chickens fed corn or sorghum based diets (with inclusion of 6 or 12% of cottonseed meal), formulated on a total and digestible amino acids base. Performance and carcass parameters when compared among the test diets and a corn-soybean diet control - Exp.2. To estimate through Gompertz equations the animals rate of growth; protein, fat and lysine deposition; feed intake, lysine efficiency of utilization and the g. of digestible lysine per kilo of weight gain in males and females feds with variable lysine digestible diets - Exp.3. In exp.1, was observed that the use of PFD+AA diet, allowed higher endogenous amino acids losses, except for lysine, isoleucine, valine and histidine (0.255; 0.390; 0.449 e 0.209mg/g DM, respectively) that were highest when the EHC was fed. Arginine (0.249mg/g DM) and leucine (0.417mg/g DM) were highest when the PFD was fed. Feeding the PFD+AA diet stimulate digestive enzymes production and also decrease errors and processing difficulties with EHC. The EHC and PFD+AA diets methods showed the highest mean TDC for crude protein, being for the SAA, corn (C), sorghum (S), soybean meal (SBM) and cottonseeed meal (CSM) of 99.6; 91.7; 90.7; 90.5 and 90.2%, respectively. The inclusion of the CSM reduced the digestibility of CP, being TDC of the diet with C+SBM 86.9%. For the diets with C+CSM6, C+CSM12, S+CSM6 and S+CSM12 the TDC was respectively of 85.5; 84.4; 86.4; 85.3%. The diets with corn or sorghum and inclusion of 12% of cottonseed meal presented TDC for methionine, lysine and threonine of 91.0; 87.1; 81.0% and 91.2; 88.0; 83.1%, respectively. Smaller than observed values for diet with C+SBM (94.4; 92.2; 84.9%). In Exp.2, The diets were the same complete diets of experiment 1, however, formulated with total (TAA) and digestible amino acids (DAA). There was no effect on weight gain (WG), feed intake (FI) and feed conversion (FC) of the birds fed with C+SBM diet and the other treatments, except for the birds fed with formulated C+CSM12 TAA diet, that showed reduced WG (2.6%) when compared with the C+SBM diet. The birds fed diets formulated with DAA showed the higher WG (1492.8g) and the better FC (1.698) that the birds fed diets with TAA (1461g and 1.732, respectively). The interaction between cottonseed meal and formulation type showed that the use of DAA allowed the inclusion of 12% of CSM, increasing 52g in WG. There was no effect on carcass parameters between birds fed C+SBM diet and other diets. However, birds fed C+CSM12 AAD showed higher carcass weight (1397g), breast weight (446g) and breast filet weight (335g) that the birds fed with C+SBM (1352, 430 and 324g, respectively). Formulations based in digestible amino acids provided better performance and carcass yield that total amino acids, and allowed the inclusion of 12% of cottonseed meal without reduction of the parameters evaluated. In Exp. 3, In the period form 1 to 42 days of age was observed that reduction of 6% in the levels of digestible lysine negatively affected WG and FC of males and females, however, lysine levels didn t make significant alterations body nutrient deposition, except for fat that was deposited in larger amounts when the birds received 6% less dietary lysine. Animal growth rate followed closely daily body protein deposition: 1,4; 4,5; 13,9 and 15,2 g in males and 1,6; 4,6; 12,4 and 11,6g in females, respectively for 7; 21; 35 and 42 days of age. During the period of 36 to 42 days of age females deposited higher amount of daily fat (20,8g) than males (17,6g). The amount of lysine deposited daily and the g. of lysine per kilo of gain increased with age. Growth and deposition curves indicated that at older age of slaughter larger fat and lower protein carcass deposition, mainly in females. The efficiency of utilization of digestible lysine for body lysine deposition, for males and females, at 7; 21; 35 and 42 days of age, were respectively of 49.6; 78.3; 66.4; 56.1% and 55.0; 81.0; 67.0; 57.4%. Based on lysine deposition and efficiency utilization, weight gain and average weight (AW), the following equations were generated: male Y (g Lysine Dig/kg gain) =13,815 + 0,5638 AW + 1,1431 AW2, R2 = 0,99 and Female: Y (g Lysine Dig/kg gain) =13,107 + 1,9773 AW + 0,6571 AW2, R2 = 0,99. The equations to estimate g. of digestible lysine per kilo of gain were 13.9; 14.7; 18.5 and 21.5 g/kg gain for males and 13.3; 14.8; 18.0 and 19.9 g/kg gain for females, respectively from 1 to 7, 8 to 21, 22 at 35 and 36 to 42 days of the age.

ASSUNTO(S)

nutricao e alimentacao animal broilers (poultry) aminoácidos desempenho amino acids frango de corte performance dietas diets

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