Un esperimento di insilamento del loglio italico (Lolium multiflorum Lam.) inquinato di terra

30 round bales of 2nd cut Italian ryegrass, harvested at 3 levels of prewilting - 22%, 28% and 33% DM content - were sealed in polythene bags. A sample of the herbage used to prepare each bale was chopped and packed into a laboratory silo maintained at 22°C for the same pe¬riod as the bales (120 days), as a check of ordinary fermentation conditions. The herbage was shown to have a WSC content rainging from 8.1% to 12.1% of DM, a WSC:TN ratio varying between 5.0 and 7.5, unfavou-rable for satisfactory fermentation process, and a high SiO2 content (3% of DM) due to soil contamination. Laboratory silages proved to have similar characteristics as the bale silages. In the latter, the SN, NH3-N, acetic acid and meq VFA content ranged within acceptable values. Even though the bu¬tyric acid concen-tration decreased from 27.8? to 12.7? with the increasing of bale DM, these levels were high enough to indicate lowered silage quality. This effect was related to the soil con¬tamination that increased the growth of butyric clostridia, which were insufficiently inhibited by the lactic acidification. Over the 7 days period of silage sample exposure to air, DM los¬ses did not exceed 1%. As the DM increased and the butyric acid decreased, the "in vitro" DOMD (Tilley and Terry) increased from 55.8% through 62.5% to 69.9% and the voluntary intake in cattle increased from 8.61% through 8.63% to 9.14% of LW0.75. In conclusion, it should be emphasised that great care is neces¬sary during field treatments for forage wilting and harvesting because soil contamination lowers the value of silage by affecting conservation quality.