Effect of fermented juice of epiphytic lactic acid bacteria on the fermentation quality of alfalfa (Medicago sativa L.) silage and its energy and nitrogen utilization by dry cows

摘要

The 1st growth alfalfa (Medicago sativa L.) was ensiled into the lapping round-bales after treatments of wilting (W), with fermented juice of epiphytic lactic acid bacteria (FJLB) after wilting (W-FJLB), and with FJLB directly after cutting (D-FJLB). Effects of treatments of wilting and FJLB additive on chemical composition and fermentation quality of the silage were examined. A constant-feeding trial of three total mixed rations (TMR), composed of 50 percent alfalfa silage, 20 percent oats hay and30 percent barley grain based on total digestible nutrients (TDN) content, was carried out to determine the microflora and digestion activity in the rumen and the energy and nitrogen utilization using two ruminally fistulated dry cows. The FJLB additivesignificantly (P<0.05) improved the silage quality, as shown by the lower pH value and the higher concentrations of lactic acid and volatile fatty acids. The higher nutritive value of the alfalfa silage in the TMRs of W-FJLB and D-FJLB compared to thatof the W silage was observed with their significantly (P<0.05) higher in vivo digestibility of dry matter (DM), organic matter and nitrogen free extracts and significantly (P<0.05) higher TDN content. This was in good agreement with higher in situ DM digestibility of the W-FJLB and D-FJLB alfalfa silage. The greater improvement of nitrogen retention in the dry cows fed on the TMRs of W-FJLB and D-FJLB was attributable to higher amounts of urinary allantoin, which was associated with higher bacterial growth in the rumen due to synchronized supply of energy and nitrogen to rumen microorganisms.