Removal of autumn-growth herbage using sheep: Effects on yield and quality of first cut silage and subsequent cow performance

Grass which grows during the autumn is perceived by some farmers to have a negative impact on the nutritive value of silage produced the following spring. The impact of removing herbage in the autumn using sheep, on silage yield and quality the following spring, and on performance of cows offered these silages, was investigated in two experiments. Following harvest of third-cut silage in September, a grass sward was split into blocks which were either grazed by sheep during November and December or left ungrazed. Herbage was harvested and ensiled the following May and offered to late-lactation Holstein cows in a two-period balanced change-over design feeding experiment comprising two 28-d periods. In Experiment 1, silage quality was unaffected by autumn grazing treatment but in Experiment 2, silage from swards grazed in autumn had a higher metabolizable energy concentration (0.5 MJ kg⁻¹ dry matter [DM]; p = .016). In Experiment 1, intakes were unaffected, while cows offered silage from the grazed sward (GS) had a greater milk (0.8 kg d⁻¹; p < .001) and protein yield (0.03 kg d⁻¹; p = .014) than cows offered silage from the ungrazed sward, but fat plus protein yield was unaffected. In Experiment 2, cows offered GS had greater DM intake (1.5 kg d⁻¹; p < .001) and fat yield (0.15 kg d⁻¹; p = .047), but fat plus protein yield was not significantly different between treatments. In conclusion, winter grazing using sheep has potential to improve silage quality, but with marginal benefits on individual cow performance.