It has been demonstrated previously that sward height has a large effect on herbage intake and performance of spring calving cows and their calves (Wright and Russel, 1986) with maximum cow and calf live-weight gain occurring when sward height is maintained at 8 to 10 cm. No comparable information is available for autumn calving cows, and the aims of the present experiment were to examine the effect of sward height on cow and calf performance, in the pre- and post-weaning periods in cows that were turned out to pasture in late lactation at two levels of body condition.

The experiment was a 2 x 2 x 2 factorial, with two levels of winter feeding, two sward heights from turn-out to weaning, and two sward heights from weaning to housing. During the summer grazing periods there were two replicates. Thirty-nine Hereford x Friesian cows (mean calving date 17 Sept, 1986) with Charolais-cross calves were used. The experiment started on 30 October 1986 when the cows and calves were housed in two groups. One group (L) was fed silage alone and the other group (H) was fed silage plus barley. Estimated daily metabolisable energy intakes were 63 MJ (L) and 92 MJ (H). Calves were fed 1 kg barley/day plus hay ad 1ibitum. The cows were mated to Charolais bulls for 8 weeks from 15 November 1986.