Effect of Wilting and Formic Acid Treatment on Silage Preservation and Performance of Autumn-Calving Cows

An area of 17 ha of perennial ryegrass was divided into five equal portions, mown, and harvested with a precision-chop forage harvester and ensiled as follows: 1. Immediately after mowing (U). 2. Immediately after mowing treated with 2.7 1/t of 85% formic acid (UA). 3. After 36 h wilting (W). 4. After 36 h wilting treated with 2.71/t of 85% formic acid (WA). 5. After 60 h wilting (LW). The grass was extensively sampled entering the silo and samples were taken from each clamp at intervals after ensiling. The silages were evaluated in a radomised block feeding trial with 45 autumn-calving cows in early lactation. The silages were offered ad libitum and supplemented with 5.0 kg/d of a barley/soyabean meal concentrate (165 g/kg crude protein). All the silages were well preserved. Wilting increased silage dry matter content (g/kg) from 212 and 205 in silages U and UA to 288,314 and 392 in silages W\ WA and LW, respectively. Silage dry matter intakes were higher (p < 0.001) on silages W and WA compared to U and UA and also on silage LW compared to U (p < 0.05) and UA (p < 0.01). Milk yield was not significantly influenced by wilting and partial feed conversion efficiencies (kg of milk/kg silage dry matter intake) were lower (p < 0.001) on silage W (1.58) and WA (1.52) compared to U