Predictions of energy digestibility in pig feeds

Feed samples were collected from feedstuffs and some diets that had been evaluated in vivo for digesibility in balance trials with growing pigs in Finland (n=33), Denmark (n=67) and Sweden (n=37). The samples covered a wide range of feedstuffs used in pig feeds and were analysed for neutral detergent fibre (NDF) and their in vitro digestibilty of dry matter or organic matter (IVDOM) according to a three-stage method (total tract). The effect of NDF content and IVDOM on the dE in the pig feeds were subjected to linear regression analysis. The content of NDF (g kg-1 DM) was closely related (P < 0.001) to the in vivo variations in dE (digestibility of energy) (%) in samples for each country, as well as for all samples including all countries (dE = 92.9 - 0.09 x NDF; n=137, R2=0.82, RSD=4.62). Also, the in vitro digestibility of OM (IVDOM, %) in was closely related (P < 0.001) to the in vivo variations in dE (%) in samples for each country, as well as for all samples including all countries (dE = - 6.61 + 1.02 x IVDOM; n=144, R2=0.87, RSD=3.99). It was concluded that NDF and IVDOM could be used to predict the dE in pig feeds with similar precision. This provides an alternative approach for estimating the energy value of pig feeds to that currently used, and could form the basis for a future common energy evaluation system in the Nordic countries.