Equações de predição dos valores energéticos do milho e do farelo de soja para suínos em crescimento com validação ex post

Abstract

The aim of this study was to determine and validate prediction equations for digestible (DE) and metabolizable energy (ME) of corn and soybean meal for growing pigs. The prediction equations were developed using data from chemical composition and digestibility and metabolizability of 30 and 25 samples of corn grain and soybean meal, respectively, evaluated in experiments at the Embrapa Suínos e Aves. The equations were estimated through regression analysis, using the REG procedure of SAS and adjusted R² was the criterion of choice to select the best models. Two equations were estimated for DE and two for ME, of corn and soybean meal. To validate the equations, two experiments were performed to determine the values of DE and ME with five samples of corn grain (Experiment I) and five samples of soybean meal (Experiment II). In each experiment, 48 growing pigs with an initial weight of 54,21±1,68 kg (Experiment I) and 54.40 ± 1.76 kg (Experiment II), were sorted in a complete randomized block design with 6 treatments (Experiment I: 1 reference diet and 5 test diets composed of 60% of the reference diet and 40% corn, and Experiment II: 1 reference diet and 5 test diets composed of 70% of the reference diet and 30% soybean meal) and 8 replicates. The experimental unit was the animal. Based on the DE and ME values obtained in the experiments, and in the predicted values obtained with the equations, we proceeded to validate the equations, using the REG procedure of SAS. The criterion for selection of the best model was the lowest prediction error (pe). After validation, the equations that best fit to estimate the digestible and metabolizable energy of corn for growing pigs were: DE = 11812 – (1015.9CP) – (837.9EE) – (1641ADF) + (2616.3Ash) + (47.5CP2) + (114.7CF2) + (46ADF2) – (1.6NDF2) – (997.1Ash2) + (151.9EECF) + (23.2EENDF) – (126.4CPCF) + (136.4CPADF) – (4.0CPNDF), with R2 = 0.81; pe = 2.33 and ME = 12574 – (1254.9CP) – (1140.5EE) – (1359.9ADF) + (2816.3Ash) + (77.6CP2) + (92.3CF2) + (54.1ADF2) – (1.8NDF2) – (1097.2Ash2) + (240.6EECF) + (26.3EENDF) – (157.4CPCF) + (96.5CPADF) – (4.4CPNDF), with R2 = 0.89 e pe = 2.24. For soybean meal the equations that best fit were: DE = 48153 – (1586,1CP) + (744,5EE) + (363,6CF) – (1398,3Ash) + (15,5CP2) – (170,8EE2) – (29,3CF2) + (5,4ADF2) – (2,5NDF2) + (90,6Ash2) – (48,2EEADF) + (33EENDF), with R² = 0.88 and pe = 2.32 e ME = 12692 – (2397,7Ash) – (56,8EE2) + (164,9Ash2) – (102,2EECF) – (12,2EEADF) + (67,6EENDF) + (5,5CPCB) – (2,9CPNDF), with R2 = 0.65 and pe = 1.69.