Fresh and ensiled forage plants—total composition, silage losses and the prediction of silage composition from the crop

Abstract

AbstractTwenty ley and whole‐crop samples were analysed before and after ensiling to determine the proportion of dry matter (DM) that could be accounted for by the sum of 12 chemical assays for ash, ash‐excluded‐amylase‐treated neutral detergent fibre (aNDFom), starch, water‐soluble carbohydrates (WSC), pectin, crude protein (CP),CPinaNDFom (CPndf), ammonia, crude fat, phenolics, plant organic acids and liquid fermentation products (acids and alcohols). Crop components, utilized during silage fermentation and the possibility of predicting silage composition from that of the crop, were also investigated. Samples consisted of timothy and red and white clover, harvested at early and late maturities in two cuts per maturity and of whole‐crop barley, wheat and maize, harvested at early, intermediate and late stages of maturity. Ley crops were wilted to reach aDMcontent of approximately 400 g/kg, whereas whole crops (WC) were not wilted (151–757 gDM/kg) before ensiling. The average sum of analytes was 1022 and 981 g/kgDMfor crops and silages respectively. An overall closeness to complete recovery indicates that no major plant components were missing from the analyses. Relative proportions of pectin, plant organic acids and phenolics, which are rarely analysed, were approximately 60:40:2 (w/w). Ash,aNDFom, crude fat andCPwere almost completely recovered after ensiling, whereas partial metabolism reduced recoveries of starch (81%),CPndf (62%), plant organic acids (65%), pectin (64%) andWSC(29%). Only the four analytes with high silage recoveries could be reasonably well predicted from parent crop levels with mean prediction error from 0.065 foraNDFom to 0.167 for crude fat.