Effects of Microbial Inoculant on Fermentation of Alfalfa and Corn

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Abstract
Second cutting alfalfa (Medicago sativa L.), wilted to 45% dry matter, and whole plant corn (Zea mays L.; 40% dry matter) were mixed with a microbial inoculant [Lactobacillus plantarum, L. brevis, Pediococcus acidilactici], the inoculant carrier, or no additive and ensiled into 200-L steel drums. Addition of microbial inoculant at rate of 1 kg additive/2,000 kg wet forage resulted in approximately 7,000 to 10,000 viable anaerobes applied to each gram of wet forage. Microbial inoculation did not affect the following fermentation parameters: lactic and acetic acid production, pH decline, ammonia and nonprotein nitrogen production, or total and acid-tolerant anaerobe count in either forage. Forage pH declined faster and to a lower level in corn than in alfalfa, even though nearly twice as much acid was produced in alfalfa as in corn. Protein degradation, measured by ammonia and nonprotein nitrogen concentrations, was more extensive in alfalfa than corn. There was no difference in the total number of anaerobes between forage species; however, acid-tolerant anaerobes tended to increase with days ensiled for alfalfa but not for corn. It is possible that there are differences in the metabolic characteristics of microorganisms that develop in different forage species.