Effects of extended wilting, shading and chemical additives on the fatty acids in laboratory grass silages

This work investigated the range of fatty acid concentrations in grass silages made from the regrowth of perennial ryegrass Lolium perenne using different techniques involving combinations of shading of the crop before cutting, wilting and the use of chemical additives. The effects of the different silage additives on overall fermentation were large, with many of the formic acid and formalin‐treated silages having a very restricted fermentation. Nonetheless, effects on levels and proportions of fatty acids were numerically small. The major differences between silages were generated during field operations (shading and wilting), with little further changes in fatty acids within the silage clamp. The extended wilt had the most dramatic effect on fatty acids with a marked reduction in both total fatty acids (24·6 vs. 17·5 g kg−1 dry matter; s.e.d. = 0·65, P < 0·001) as well as in the proportion of total fatty acids as α‐linolenic acid (C18:3n‐3; 0·55 vs. 0·48; s.e.d. = 0·013, P < 0·01). Shading the grass with a black plastic sheet for 24 h before cutting had a similar effect.