It is generally acknowledged that lactating dairy cows offered grass silage consume less dry matter (DM) and produce less milk with a lower protein concentration than cows offered fresh pasture. However, there is little evidence to indicate whether these effects are due to the influence of ensiling per se or to differences in herbage composition. The aims of the current experiment were to evaluate the effects of ensiling per se and silage fermentation pattern on forage intake and dairy cow performance.

A perennial ryegrass sward (Lolium perenne cvs Barlenna and Talbot) was divided into 4 areas (A, B, C and D) comprising one area of 6.7 ha (area A) and three areas of 0.7 ha (areas B, C and D). Each area received a total of 361 kg N, 74 kg P2O5 and 144 kg K2O/ha over the season. From 1 June 1993, herbage was harvested once daily from areas B, C and D using a double chop forage harvester and offered to dairy cows housed indoors during weeks 1, 2 and 3 respectively (Treatment G).