Factors Affecting Corn Silage Quality in Hot and Humid Climates

Dairy farmers in many parts of the world rely on corn silage as a source of digestible fiber and readily fermentable energy for their cattle. In Florida, Georgia and many tropical countries, such farmers face several climatic challenges that can complicate corn silage production including temperatures that reduce the rate of photosynthesis (Crafts-Brandner and Salvucci, 2002) and reduction in potential yields due to faster crop life-cycles. In addition, the hot, humid conditions that occur during the corn growing season in these states is partly responsible for the production of four generations per year of European corn borer (Ostrinia nubilalis) compared to one generation per year in Northern states. These climatic conditions are also conducive for proliferation of many bacterial and fungal pathogens which cause stalk rot, smut, leaf blight and southern rust, and predispose to growth of mycotoxin-producing Penicillium, Aspergillus and Fusarium molds (Ono et al., 1999; Raid and Kucharek, 2005; Samapundo et al., 2005). In addition to affecting crop growth and disease incidence, previous studies showed that these climatic factors have adverse effects on silage fermentation and aerobic stability (Dewar et al., 1963; Garcia et al., 1989; McDonald et al., 1966; Muck, 1987). Rainfall at harvest can increase proteolysis in the silo ((McDonald et al., 1991) and effluent production (Fransen and Strubi, 1998) thereby reducing DM recovery. Ensiling at high temperatures reduces lactic acid concentration and aerobic stability, and increases pH and DM losses (Ashbell et al., 2002; Weinberg et al., 2001). Most of these findings were based on grass and alfalfa silages and the experiments examined the effect of temperature or moisture on silage fermentation