Different heat treatments and sealing effect on the nutritive value of Lucerne hay

Abstract This study investigated the comparative effects of conventional hot-air oven heating (CHO), microwave heating (MW) and sealing effect on the nutritive value of lucerne hay. Equivalent energy (125 J.g−1) was applied with a 1.1 kW of MW oven for 60 seconds (s) or a 3.06 kW CHO oven for 350 s. The required equivalent energy level was measured based on a preliminary calibration trial. Two heating method (CHO and MW) and sealing condition (SC) applied as treatment factors in this study. A two-way analysis of variance (P < 0.05) was used to measure the effect of different factors on some properties of lucerne hay. The dry matter (DM) percentage of lucerne hay was increased when MW treatments were applied on both sealed and non-sealed lucerne hay compared with the control. Both heating method and their interaction with SC had negative effects on crude protein (CP) percentage. DM digestibility (DMD) and Digestible organic matter in the DM (DOMD) were decreased by 9% and 5%, respectively, in the sealed MW group, compared with the sealed control. Neutral detergent fibre % also increased by 6% in the sealed MW group, compared with the sealed control group. However, no differences in acid detergent fibre % due to any heating method and/or SC were observed in this study. The mechanisms behind these changes require further exploration.