Round-Bale Silage Harvesting and Processing Effects on Overwintering Ability, Dry Matter Yield, Fermentation Quality, and Palatability of Dwarf Napiergrass (Pennisetum purpureum Schumach)

Abstract

Round-bale silage harvesting and processing methods were assessed to evaluate overwintering ability and dry matter (DM) yield, fermentation quality and palatability of overwintered dwarf Napiergrass (Pennisetum purpureum Schumach) in the two years following establishment in Nagasaki, Japan, in May 2013 using rooted tillers with a density of 2 plants/m2. In 2014, harvesting methods under no-wilting treatment were compared for flail-type harvesting with a round-baler (Flail/baler plot) and mower conditioning with a round-baler (Mower/baler plot), which is common for beef-calf–producing farmers in the region. In 2015, the effect of ensilage with wilting was investigated only in the Mower/baler plot. Dwarf Napiergrass was cut twice, in early August (summer) and late November (late autumn), each year. The winter survival rate was greater than 96% in May both years. The DM yield in the Mower/baler plot did not differ significantly for the first summer cutting or the annual total from the Flail/baler plot, but did show inferior yield for the second cutting. The fermentation quality of the second-cut plants, estimated using the V2-score, was higher in the Flail/baler plot than in the Mower/baler plot, possibly because of higher air-tightness, and the second-cut silage tended to have better fermentation quality than the first-cut silage in both harvesting plots. Wilting improved the fermentation quality of dwarf Napiergrass silage in summer, but not in autumn. The palatability of the silage, as estimated by alternative and voluntary intake trials using Japanese Black beef cattle, did not differ significantly between plots. The results suggest that dwarf Napiergrass can be better harvested using a mower conditioner with processing by a round-baler, an approach common to beef-calf–producing farmers, than with the flail/baler system, without reducing the persistence, yield, or palatability of the silage. Moreover, wilting treatment improved the fermentation quality of the dwarf Napiergrass silage when processed in summer.