Tests of 6 energy evaluation systems for dairy cows

Abstract The ability of 6 energy systems for accurate animal performance prediction was studied by means of 992 individual results from 40 feed intake trials with dairy cows. The systems are: starch equivalent system (SE), net energy fat system for ruminants (EFr), feed unit for milk production — The Netherlands and Belgium (VEM), feed unit for milk production — France (UFL), metabolizable energy system (ME), net energy lactating cows (NE 1 ). The results demonstrate that the more recent systems as VEM, UFL, ME and NE 1 are better than the SE system. The EFr system is more accurate than the SE system, but seems less accurate than the others. For all systems, except for UFL, recorded performances were on an average lower than predicted. In the UFL system, energy value of roughages seems to be underestimated. Accuracy of the systems decreases when the level of over- or underfeeding increases, which suggests that standards for body weight change may be improved.