The effect of cutting for conservation on a grazed perennial ryegrass‐white clover pasture

Abstract

AbstractContinuous stocking with sheep at high stocking rates may reduce the content of white clover (Trifolium repens) in mixed grass‐clover swards. The present experiment was carried out to investigate the effects on sward production and composition of resting a perennial ryegrass (Lolium perenne)‐ white clover sward from grazing and taking a cut for conservation.Swards were set‐stocked with 25 and 45 yearling wethers ha−1 either throughout a grazing season, or on swards that were rested for a 6‐week period and then cut in early, mid‐ or late season. In an additional treatment swards were cut only and not grazed.Net herbage accumulation was higher at the lower of the two stocking rates and was marginally increased by the inclusion of a rest period at the high but not the low stocking rate. Clover content was higher at the lower stocking rate and was increased by the inclusion of a rest period by 30% at 45 sheep ha−1and by 11% at 25 sheep ha−1 The effect was most marked at the end of the rest period before cutting. When rested from grazing the tiller density of ryegrass decreased although tiller length increased, and clover stolon length, petiole length and leaflet diameter increased though leaf and node number per unit length of stolon decreased; the reverse applied when the sward was returned to grazing after cutting.At the high stocking rate, rest periods in mid‐season or later maintained the greatest clover content and marginally increased total net herbage accumulation. At the low stocking rate the timing of the rest period had no significant effect on total net herbage accumulation or on clover content.These results show that the combination of grazing and cutting is of benefit where the stocking rate is high enough to threaten clover survival and limit sheep performance. However, at such a stocking rate, feed reserves are at a minimum throughout the grazing season and so opportunities for resting the sward are probably low.