Data from 11 experiments, conducted mainly at ADAS Liscombe Research Centre during 1989-1992, were used to compare silages made with additives which included formic acid, an acid-salt-type additive, sulphuric acid, liquid inoculant and a cultured inoculant with a nonadditive-treated control. The silages were made from herbage with dry matter (DM) 170 g/kg and watersoluble carbohydrate (WSC) 21 g/kg.
Compared with the non-additive-treated silage, formicacid treatment significantly reduced silage pH, ammonia-N, acetic acid, butyric acid, total short-chain fatty acid and total acid content and significantly increased the proportion of lactic acid expressed as a proportion of the total acids. The acid-salt-type additive significantly decreased pH, lactic acid, acetic acid, total short-chain fatty acids and total acid content and significantly increased WSC. Sulphuric acid significantly reduced pH and ammonia-N. The liquid inoculant had no significant effect upon any silage fermentation parameters, and the cultured inoculant significantly reduced pH and acetic acid and significantly increased the proportion of lactic acid expressed as a proportion of total acids.
Effluent production was higher with acid treament, but the effect was not significant. The effluent from the acid-salt-type additive-treated silage had a significantly higher DM and WSC than the other treatments.
The silage DM intakes of the formic acid (5)36 kg/d), sulphuric acid (5)29 kg/d) and the acid-salt-type additive (5)20 kg/d) were significantly higher than those of the untreated silage (4)76 kg/d), and the daily liveweight gains given by the acid-salt-type additive (0)71 kg/d) and formic acid (0)68 kg/d) treated silages were significantly higher than those of the untreated silage (0)58 kg/d).
It is suggested that the improvements in silage preservation obtained from additive use at ensilage were closely reflected in terms of animal performance. The acidsalt-type additive and formic-acid treatments were most effective, the liquid inoculant and sulphuric acid inter mediate between the acid-salt-type additive or formic acid and untreated silage, whilst the cultured inoculant was similar to untreated silage.