Fermentation Quality and Aerobic Stability of Silages from Forage Crops Mixed with Bamboo Silage in Southern Kyushu, Japan

Abstract

Underutilization of bamboo contributes to the degradation of woody environments in southern Kyushu, Japan. A novel approach to using bamboo involves processing it to finely ground silage, although this product has shown inferior digestibility and palatability compared to traditional forage crops. This study evaluated the chemical composition, fermentation quality, and aerobic stability of silages produced from Italian ryegrass, maize, and Rhodes grass mixed with 10% (v/v) bamboo silage, ensiled for 30-40 days. One-day wilted first-cut Italian ryegrass and Rhodes grass and direct-cut maize were finely chopped, mixed with bamboo silage at a 9:1 volume ratio, and vacuum-sealed in polyethylene bags, with control silages produced without bamboo addition. Digestibility tended to decrease in bamboo-mixed maize and Rhodes grass silages. The addition of bamboo silage resulted in a significant decrease (p<0.05) in pH by 0.45 in Italian ryegrass, a trend toward lower pH in Rhodes grass, and a tendency for pH to increase in maize. Fermentation quality was improved by the addition of bamboo silage in Italian ryegrass and Rhodes grass, with significant increases (p<0.05) in contents of lactic acid by 2.91% Dry Matter (DM) and acetic acid by 1.03% DM, respectively, contrasting with a trend toward reduced lactic acid content in maize. Aerobic stability, measured as the time to reach a temperature increase of >2°C above ambient, was highest in Italian ryegrass silage with bamboo, which maintained stability for more than 6 days after air exposure, compared to significant temperature rises detected at 15 and 29 h in maize and Rhodes grass silages, respectively. Fermentation quality, including pH, lactic acid, and acetic acid contents, was maintained in Italian ryegrass silage mixed with bamboo for a week after air exposure, while rapid deterioration was observed in maize and Italian ryegrass silages with and without bamboo silage addition. It is concluded that wilted Italian ryegrass mixed with 10% bamboo silage may enhance the handling efficiency of silage after opening silos in early June for the site in southern Kyushu, Japan.