Effect of invasive slug populations (Arion vulgaris) on grass silage

At low DM level, the effect of four additive treatments, control (C), inoculation with Lactobacillus plantarum (LP), a formic, propionic and benzoic acid mixture (ACID) and a chemical additive containing benzoic acid, NaNO2, hexamethylenetetramine and propionic acid (CHEM) were tested. Increasing slug contamination gave increasing quality reductions both in silages containing 253 and 372 g DM/kg. Compared with untreated silage, LP-treatment did not improve silage fermentation quality of contaminated crops. Treatment with ACID and CHEM, however, considerably improved the quality of heavily contaminated silages. The much higher crude protein concentration in slugs compared to grass crop made slugs a more “difficult-to-ensile” material. Wilting of the harvested crop to 372 g DM/kg was not sufficient to control silage fermentation of slug contaminated crop. With contamination levels from 138 to 553 g fresh slug weight/kg crop DM, efficient silage additives were able to ensure acceptable fermentation quality of grass silages.