The effect of urea and molasses addition into corn harvested at the milk stage on silage quality and digestible nutrient yield

摘要

The aim of this study was to determine the effects of urea or urea plus molasses addition into corn harvested at the milk stage on the silage quality and in vitro digestibility of silage. To achieve this objective, four different corn varieties (Rx-947, 33-94, Frassino and Arifiye) harvested at the milk stage were utilized. Silage samples were added 0.5% urea or 0.5% urea plus 4% molasses and ensiled in mini-silos (1 L in volume). Silage samples were analysed for chemical composition, pH and organic acids (lactic acid, acetic acid, propionic acid and butyric acids). In vitro dry matter (DM) digestibility and digestible DM yields of silages (kg/da) were also determined. Urea addition increased silage crude protein (CP) in addition to silage pH. Urea or urea plus molasses addition generally decreased silage lactic acid content, but these decreases were only significant in the Rx-947 and Frassino varieties. While silage acetic acid contents were not affected by urea and molasses addition, butyric acid concentration increased in the Frassino variety with urea addition, and decreased in the Arifiye variety with urea and urea+molasses and the 33-94 variety with urea+molasses addition. Urea plus molasses addition increased silage DM digestibility in the Frassino variety, but this effect was not significant for other varieties. Digestible DM yields were not affected by additives (P > 0.05). In conclusion, the addition of 0.5% urea or 0.5% urea plus 4% molasses into corn harvested at the milk stage improved the chemical composition of silages, but had no positive effect on silage quality.