Effect of stage of growth on the chemical composition, nutritive value and ensilability of whole-crop barley
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Date
2009
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Abstract
Chemical composition, nutritive value and ensilability of whole-crop barley as a supplementary feed for dairy cows was investigated using a range of maturities of barley (seed coat ripe-GS 69, early dough stage-GS 82, soft dough-GS 87 and grain ripe-GS 90) in small scale silos. The ensiling experiment was based on a complete randomised design with three replicate silos per harvest date. Twelve 0.225 m(3) plastic silo (were used in the experiment and silo were sampled on opening for chemical composition and nutritive value. The fermentation process reduced the concentrations of water-soluble carbohydrate in the ensiled forage compared to the fresh forage. The proportion of residual WSC in silage did however increase with increasing crop maturity (0.051, 0.077, 0.167 and 0.560 of WSC retained in. the silage after the process of fermentation from forages cut at GS 69, 82, 87 and 90 respectively). Silages that were made from forage cut at the most mature stage of growth had a substantially lower production (P<0.001) of total fermentation acids (38.9 g/kg DM for GS 90) compared to those made from the least mature forage (203.4 g/kg DM for GS 69). The pH and concentrations of the various fermentation acids for silages made with the least mature forage (GS 69) were typical of acetic acid dominated fermentation. These silages contained little or no butyric acid and had a pH of 4.5 and contained high concentrations of ammonia-N (186 g/kg total N). Silages produced from forages cut at growth stage 82 were similar to those conserved from immature forages, having acetic acid dominated fermentation (lactic acid to acetic acid ratio of 1:1.22), relatively high pH (4.85) and high concentrations of ammonia-N (141 g/kg total N). These silages differed from those made from the most immature forage insofar that they contained high concentrations of butyric acid (50.5 g/kg DM). The processes of fermentation were affected by the stage of growth of the forage at ensiling and hence the economics of silage production. If the forage was too immature at ensiling, the yield of crop would be compromised but the silage produced may have moderate to high nutritive value and reasonable aerobic stability during the feed out phase. If the whole-crop forage was grown as a crop to secure high levels of supplementary feed from an alternative forage source (other than grass),the trade-off between yield, nutritive value and losses of feed immediately after silo opening would suggest the crop should be harvested between 350 and 450 g DM/kg dry matter. (C) 2009 Elsevier B.V. All rights reserved.
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Cereal silage, Chemical composition, Nutritive value, Deterioration, SILAGE, DIGESTIBILITY, ENSILAGE, MATURITY, FORAGE, WHEAT, STEM