Growth, chemical components and ensiling characteristics of king grass at different cuttings

Abstract

In order to effectively use and ensile king grass (Pennisetum purpureum × Pennisetum americanum), the present research investigated growth rate, yield, chemical components and silage fermentation quality of different cuttings. King grass was harvested four times, and the 1st and 3rd cuttings were ensiled directly or after wilting for 12 and 24 h. The results showed that the dry matter daily growth of 2nd cutting was significantly higher than that of other cuttings, and the 4th cutting was the lowest (P < 0.05). The contents of crude protein (CP), crude fat and water-soluble carbohydrates (WSC) tended to reduce, and crude ash tended to increase with the increase of cutting times. All four cuttings of king grass had higher WSC content, lower buffer capacity and much lactic acid bacteria, the silages made from unwilted 1st cutting and 3rd cutting were of good fermentation quality, indicated by low pH values and high V-scores. Wilting had different effects on the 1st cutting and 3rd cutting silages in pH value and NH_3-N content, the 1st cutting silage tended to increase the pH values and NH_3-N content, with moisture content reduction, while the 3rd cutting silage tended to reduce NH_3-N content and its pH value was not affected by wilting (P > 0.05). Although the 3rd cutting silage had better aerobic stability than the 1st cutting silage, they all were not stable within 6 days of aerobic exposure. Considering the contents of CP, crude fat, crude fiber, crude ash and WSC, the 1st cutting of king grass might have best nutrient value, while the 4th cutting was contrary. Different cuttings of king grass could be well preserved by natural fermentation, but their aerobic stability was poor.

Keywords: Cuttings, ensiling, king grass, nutrient component, wilting