Prediction of true metabolizable energy from chemical composition of wheat milling by-products for ducks

Abstract

The present study was conducted to evaluate the effect of chemical composition of wheat by-products on the TME value to ducks and to establish the prediction models estimating TME. Seven representative samples were selected from 23 wheat by-products millings samples based on the neutral detergent fiber (NDF) content. According to the Sibbald method, male Cherry Valley ducks were chosen to assay the TME of 7 representative samples. Stepwise regression analysis was performed to establish the prediction equations of TME using CP, ether extract (EE), NDF, acid detergent fiber, crude fiber, and gross energy (GE) as independent variables. The NDF, CP, and DM of 23 samples of wheat by-product averaged to be 33.39 +/- 11.04%, 19.2 +/- 3.25%, 87.17 +/- 0.95%, respectively. The TME values of 7 representative samples averaged 12.02 MJ/kg, with much larger CV than GE (17.72 vs. 2.82%). The crude fiber, NDF, acid detergent fiber were highly but negatively correlated with TME (P < 0.01), in which the greatest correlation coefficient (r = -0.969) was observed between NDF and TME. No significant correlation of CP, EE, ash, and GE to TME was found among the 7 representative samples. The optimal equation in terms of R(2) from using a single chemical analysis was obtained in the total group: TME = -0.1564NDF + 17.4696 (R(2) = 0.94, P = 0.0003), and the TME prediction equation was improved by the addition of the EE and CP content to sequential analysis: TME = -0.17NDF + 0.98EE - 0.27CP + 19.31 (R(2) = 0.99, residual SD = 0.35, P < 0.01). The results of present study suggest that NDF could be used as an effective indicator for the prediction of the TME value of wheat by-products for ducks.