Ensilage of wilted whole crop rice (Oryza sativa L.) using a roll baler for chopped material: Silage quality in long‐term storage

We examined the effects of long‐term storage on the fermentation quality, chemical composition, and digestibility of wilted whole crop rice silage prepared using a roll baler for chopped material (set chop length, 13 mm) and compared the results with those obtained by using a conventional roll baler. The roll balers were used for ensiling whole crop rice of three types: (i) dough‐ripe stage with light wilting (45% dry matter); (ii) dough‐ripe stage with heavy wilting (65% dry matter); and (iii) yellow‐ripe stage with light wilting (45% dry matter). The apparent dry matter density was higher in the ensiled roll bales composed of chopped whole crop rice (chopped bales) than in those composed of non‐chopped whole crop rice (conventional bales) (195–250 kg m−3 vs 156–218 kg m−3, respectively). The formation of volatile fatty acids and ammonia‐nitrogen was low in all types of silage. Further, no marked differences in the chemical composition and apparent dry matter digestibility were observed between silage from the two types of bales. However, there were significant differences in their lactic acid and ethanol contents. The lactic acid production in the conventional silage was low (0.08–0.14% fresh matter), whereas that in the chopped silage was high (0.71–0.97% fresh matter). A lower pH value (pH 4.0–4.3) was retained in the chopped silage after 10 months of storage. High ethanol production (1.1–2.5% fresh matter) was observed in the conventional silage, whereas ethanol production decreased to less than 1% in the chopped silage. These results indicate that although the ethanol fermentation is readily enhanced in the ensilage of wilted whole crop rice performed by a conventional baler, the ensilage performed by a baler for chopped material encourages lactic acid fermentation and suppresses ethanol production over a wide moisture range throughout the long‐term storage.