The effects of temperature on the effluent production potential of grass silage

The effects of temperature on silage effluent production were examined. In the first experiment, samples of perennial ryegrass (Lolium perenne) underwent fermentation at 20 degrees C for between 52 and 66 d. The samples were then transferred to rooms at temperatures between 5 degrees C and 27 degrees C. Effluent production during creep consolidation was measured. Increasing temperature resulted in a significant increase in effluent production. There was a strong linear relationship between the mechanical properties of the silage and the amount of effluent produced. In the second experiment, Italian ryegrass (Lolium multiflorum) samples were ensiled at temperatures between 5 degrees C and 25 degrees C. The higher temperature treatments had faster and more extensive fermentations, and produced more effluent than the cooler temperatures. Again, there was a strong linear relationship between the mechanical properties of the silage and the amount of effluent produced. Increasing the temperature at the end of the experiment resulted in no extra effluent production from any treatment except that at 5 degrees C. This indicated that the effects of temperature were evident only while effluent was available for release. The effects of temperature will therefore be most evident in the early stages of ensilage. In both experiments, effluent was released from the higher temperature treatments earlier. This was probably due to the effects of temperature on the viscosity of the effluent and to fermentation effects in the second experiment. In both experiments, the increase in effluent production with temperature was equivalent to the effects to be expected from decreasing the herbage dry matter concentration by between 3% and 4%.