The use of Italian ryegrass silage in a low input dairy cow feeding system in Austrian organic agriculture

Italian ryegrass (Lolium multiflorum Lam., var. italicum) is widely known for being well suited as forage for dairy cows due to its high energetic value and promotion of high forage intakes. Performance under the conditions of organic agriculture is promising as well. Winter feeding of Austrian organic dairy cows is commonly based on preserved forages like grass silage, and when milk yields are moderate and concentrate prices are high, hardly any concentrates may be supplemented at all. The objective of this study was to determine the effects of including 30 % Italian ryegrass silage (RG) in a grass silage-based diet on the performance of organic dairy cows, with hardly any concentrate supplementation (0.7 kg DM day-1 and cow). The nutrient composition of Italian RG fulfilled expectations (118–133 g CP; 5.96–5.98 MJ NEL kg-1 DM) and its inclusion in the diet was found to improve energy intake (+3 MJ NEL d-1 and cow), but did not facilitate a better energy balance (92–93 %). Grass–clover silage, which was the main forage component, unfortunately had an unfavorable fermentation quality associated with low dry matter content (209 gkg-1). This led to only moderate forage intakes (12.3–12.5 kg DM) and therefore an inadequate energy supply of the cows and ruling out any positive effects of Italian RG.