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The effect of extended moist wilting and formic acid additive on the conservation as silage of two grasses differing in total nitrogen content
Author(s) -
Anderson R.
Publication year - 1983
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740340808
Subject(s) - wilting , silage , chemistry , agronomy , formic acid , nitrate , perennial plant , nitrogen , ammonia , zoology , food science , biology , biochemistry , organic chemistry
Herbage from two contiguous areas of an S.24 perennial ryegrass sward treated with differing levels of fertiliser N (LN and HN) was used to make direct cut (D) and wilted (W) formic acid silages designated LND, LNW, HND and HNW. The major nitrogenous constituents of the herbages and silages were studied and the digestibilities of the silages determined in vivo using cross‐bred wethers. A 96 h wilt under poor drying conditions achieved DM of 26.3% (LNW) and 25.2% (HNW). Wilting had the effect of markedly increasing NPN to reach 37.4% TN (LNW) and 40.4% TN (HNW) after 96 h and there were concomitant increases in herbage free amino‐N, amide‐N and ammonia‐N. However, nitrate‐N decreased significantly during the wilting period and it was assumed that aerobic microbes were active on the crop. The ensiled herbages were well preserved, highest pH value being 4.01 (HNW) and, although NPN levels in wilted silage were significantly higher than unwilted, these did not exceed 50% TN. Changes noted in the free amino compounds included the accumulation of amides during wilting and their removal during ensilage, the accumulation of proline during wilting and the removal of arginine and accumulation of ornithine during the ensilage of wilted herbage. Nitrate also decreased markedly during the ensilage of wilted herbage, LNW and HNW herbages losing 58% and 57% of their nitrate‐N respectively. Ammonia‐N levels in LNW and HNW silages were considerably higher than in LND and HND treatments and this was tentatively linked with increased reduction of nitrate and deamination of amide and arginine during the ensilage of wilted herbages. Nitrogen digestibility coefficients were, respectively 0.672 (LND). 0.643 (LNW), 0.677 (HND) and 0.645 (HNW) and organic matter digestibility coefficients 0.698 (LNW), 0.652 (LNW), 0.666 (HND) and 0.634 (HNW). The differences in nitrogen digestibility between wilted and direct cut silages did not attain statistical significance. It was concluded that a substantial reduction in organic matter digestibility coupled with an increase in the relative proportion of low molecular weight nitrogenous compounds present were the principal effects of extended moist wilting in this experiment.