Effect of Salt on Fermentation of Alfalfa. 2. Treatment with Sodium Chloride, Clostridium butyricum, and Lactic Acid Bacteria

¹ USDA, Agricultural Research Center, US Dairy Forage Research Center, Ohio Cluster, Department of Dairy Science
² Department of Dairy Science, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691

Pure cultures of anaerobic bacteria were grown in KCl- and NaCl-treated media, and NaCl was added to alfalfa (Medicago sativa L.) inoculated with Clostridium butyricum to determine effects of salt on growth of silage bacteria and fermentation of potentially putrefactive alfalfa silage. Pure cultures of Lactobacillus plantarum, Streptococcus faecium, and C. butyricum were grown in media containing 0, 100, 200, 400, 600, or 1200 mM NaCl or KCl. Growth of C. butyricum did not occur with 100 mM or higher NaCl and 200 mM or higher KCl. Growth of the lactic acid bacteria, although slower compared to no added salt, was evident at all added salt concentrations. Freshly cut, fourth-cutting alfalfa (vegetative stage) was well-mixed and treated with 1) no inoculant and no NaCl, 2) C. butyricum and no NaCl, 3) C. butyricum and NaCl (4 g NaCl/100 g wet forage), 4) C. butyricum and lactic acid bacteria, or 5) C. butyricum, NaCl, and lactic acid bacteria. Total anaerobes. total N, pH, lactic, acetic, and butyric acids, and ammonia N were measured. Salt (NaCl) inhibited growth of Clostridium and, apparently, epiphytic lactic acid bacteria. Sodium chloride alone added to Clostridium-inoculated alfalfa did not result in a well-preserved silage. Inoculation with lactic acid bacteria was more effective than NaCl in contributing to a well-preserved silage.

Key Words: salt • lactic acid bacteria • alfalfa

Submitted on February 26, 1990
Accepted on August 6, 1990