'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 GENETIC VARIATION OF IN VITRO DIGESTION KINETICS IN MAIZE T.J. FREY, P.J. FLANNERY, J.G. COORS University of Wisconsin-Madison, Madison, WI 53706 USA

In vitro digestion kinetics can be used to estimate rates and extent of in vivo digestion of specific forages.  The objectives of this study were to evaluate the extent of genetic variation for digestion kinetic components of maize silage and evaluate the potential for prediction by near infrared reflectance spectroscopy (NIRS).  Twenty-five corn hybrids and one breeding population were grown in two environments in 1999.  Whole plant tissue was ensiled in mini-silos then prepared for analysis.  Each entry was subjected to nine periods of in vitro digestion followed by neutral detergent fiber analysis.  Preliminary data indicated significant variation among hybrids for digestion components.  The genetic variation of the germplasm as well as results from NIRS calibration will be presented and discussed.