In a rotational grazing system for dairy cows, to achieve maximum yield/cow, optimum post grazing stubble height of between 8-10 cm is recommended. At this mean height, however, selective patchy grazing and excessive stem production occurs, particularly around dung patches. Sward deterioration gets progressively worse as the grazing season progresses, resulting in a decline in pasture utilisation and output. An alternative to topping to improve sward structure is a leader-follower system with sheep, as tested In Ireland (O'Riordan, 1989). A pilot investigation was carried out in 1989 and a more detailed evaluation of the technique was made in 1990. Results for 1990 are reported in this paper.

A high yielding herd of 114 Holstein/Friesians (herd average 7200 l), in a genetic selection programme at the University of Edinburgh's Langhill Farm, were turned out on 3 May 1990. The cows rotationally grazed 2-3 ha paddocks for 3-4 days. Speed of rotation was determined by herbage availability and daily milk production, every effort being made to ensure that herbage intake to the dairy cows was never limiting.