The effect of wilting and silage additives on the fermentation of autumn made grass silage ensiled in bunkers on commercial farms in South Wales 1983‐85

Abstract

AbstractSilage making practices in respect of 130 samples of autumn made grass silages ensiled in bunkers on commercial farms in South Wales during 1983‐1985 were analysed to discern the effect of wilting and/or silage additives on fermentation. Silages were primarily made during late September and early October in fine weather from perennial ryegrass pasture which had not been grazed for 6 weeks. On average 13.9 ha of pasture was cut for silage. Analysis of 120 samples of grass showed it contained 176 g kg−1 dry matter (DM) with (g kg−1 DM) 215 protein, 240 modified acid detergent fibre (MADF), 78 water‐soluble carbohydrate (WSC) and 95 ash. Most farmers attempted to pre‐wilt grass for 1 day prior to ensilage and one quarter of them made unwilted silage. Silage making was usually completed within 6 days of starting to cut and was generally made with a precision‐chop machine. Silage additives applied were (kg t−1) formic acid (4·7), formic acid 4‐formalin (5·5), sulphuric acid‐+ formalin (5·0) sugars (14) and inoculants (0·65). Formic acid significantly reduced pH, and formic acid with or without formalin significantly reduced ammonia nitrogen (N) content of silages compared with other treatments. Protein contents of acid/formalin treated silages were significantly higher and MADF of acid with or without formalin treated silages were significantly lower than other treatments. Pre‐wilting grass prior to ensilage did not significantly increase subsequent silage DM content and significantly increased the pH of non‐additive treated silages. Unwilted silages treated with formic acid with or without formalin had a significantly lower ammonia‐N content and higher residual WSC than other treatments.It is suggested that only formic acid application either alone or in conjunction with formalin to unwilted silage was successful in producing well preserved silages and that a grass WSC content of 17 g kg−1 would be necessary to achieve this.