ENSILAGE CHARACTERISTICS OF 3 TROPICAL GRASSES AS INFLUENCED BY STAGEOF GROWTH AND ADDITION OF MOLASSES

When molasses was added during ensilage of three tropical grasses [ham il grass (Panicum maximum cv. Hamil), pangola grass (Digitaria decumbe ns) and setaria (Setaria sphacelata cv. Kazungula)] the final pH, conc entration of fermentation acids (except lactic acid) and NH3-N content were all similar after 100 days of incubation. Pangola grass silage h ad significantly higher lactic acid content (66 g/kg dry matter) than the other two. Adding either 4 or 8% (w/w) molasses reduced NH3-N, vol atile fatty acid content and pH but increased lactic acid content in t he final silages. Numbers of lactic acid bacteria remained approximate ly constant during the course of the fermentation, although large diff erences were noted in the species composition of the populations. At t he time of ensiling, only Pediococcus spp. and Leuconostoc spp. were d etected. By 5 days, the homo-fermentative population, notably Lactobac illus plantarum, dominated (43%) and remained dominant. Hetero-ferment ative rods were only detected in the 100-day silage, where they repres ented 29% of the strains isolated. Homo-fermenters were more abundant in pangola (60%) and setaria (47%) silages than hamil (27%) silages. H omo-fermenter populations were lowest in the 12-week forage. Molasses additions increased homo-fermenter populations. Pangola grass gave the best quality silage but, since the water-soluble carbohydrate content in the grasses was insufficient to promote a strong lactic fermentati on, the addition of 20 to 30 kg molasses/tonne should achieve satisfac tory preservation.