The combined effect of molasses and formic acid on quality of red-clover silage

Ecological farmers desire to grow red clover (Trifolium pratense L.) and possibly use it for silage. Red clover dominated herbage may be difficult to ensile because of low sugar concentration and relatively high buffering capacity, however. The aim of the present investigation was to study the combined effects of molasses and formic acid on quality, microbial acitivity and rate and extent of digestion in red clover silage. Three levels of molasses, 0, 40, or 100 litre ton-1 fresh matter (FM) and two levels of formic acid, 0 or 5 liter ton-1 FM were studied in a factorial combination by ensiling red clover in 260 litre silo for 60 days. Density and concentration of dry matter (DM), digestibility, ash and water soluble carbohydrates (WSC) increased with increasing levels of molasses (p less than 0.001). Crude protein (CP) decreased with increased levels of molasses (p less than 0.003). Effects from application of formic acid were similar, but less pronounced compared with application of molasses. All silages were well fermented with or without silage additives. Concentration of lactic acid and acetic acid decreased at increasing levels of molasses when no formic acid was applied (p less than 0.006). Concentrations of lactic acid and acetic acid were lower and increased at increasing levels of molasses when formic acid was applied. Thus, increasing levels of molasses reduced silage fermentation the same as application of formic acid, but to a lower extent. DM-losses during ensilage were reduced by formic acid only. Treatment with molasses had no effect on losses of effluent, but increased DM-losses. Ethanol is an indicator of yeasts growth and influx of air in the silage. Concentrations of ethanol decreased with increased rates of molasses (p less than 0.0001). Therefore, molasses reduced the air from entering the silage. Initial rate and extent of digestion was higher for silage treated with 100 l of molasses with formic acid or without formic acid. Beyond 4 h of digestion, rate of digestion was similar for all silages, but extent of digestion remained the highest for silage with 100 l of molasses. It is concluded that applying molasses and formic acid either separately or in a mixture to red clover improved silage fermentation. A combination is prefered to avoid an over-fermentated silage. Pure red clover was suitable for silage with or without a silage additive.