The effect of an acid salt-type additive on the fermentation of grass silages made in bunker silos on commercial dairy farms in Wales

The fermentation characteristics and chemical composition of 57 first-cut and 30 second-cut samples of grass silages, made in bunker silos on commercial dairy farms in Wales in 1990, and treated with a nominal 61 t^?1 of an acid salt-type additive at ensilage, is described. Typical chemical composition of grass cut for ensilage was 156 g kg^?1 dry matter (DM) and 28 g kg^?1 water soluble carbohydrate (WSC), with 181 g (kg DM) ^?1 crude protein (CP) and 232 g (kg DM) ^?1 modified acid detergent fibre (MADF). The effect of additive use was to produce silages with DM 230 g kg^?1 pH 3·93, ammonia N 70 g kg^?1 total N, with residual WSC 35 g (kg DM) ^?1, lactic acid 83 g (kg DM) ^?1, total acids 118 g (kg DM) ^?1 and butyric acid 0·7 g (kg DM) ^?1. No significant differences were found between first- and second-cut silages. Silage fermentation was restricted (i.e. lactic acid less than 60 g kg DM^?1) in only 20% of the samples.
It is suggested that on commercial farms the application rate achieved may be insufficient to produce a restricted fermentation.