Diet selection by young deer grazing mixed ryegrass/white clover pastures

Abstract

Groups of weaned red deer stags were grazed from May to December 1988 under continuous stocking management to maintain mixed perennial ryegrass/white clover pastures, with or without directdrilled 'Grasslands Moata' annual ryegrass, at sward heights of 5 cm and 10 cm. Diet selection was estimated from (a) samples of fresh ingesta collected from rumen tistulated animals, and (b) defoliation of marked populations of grass tillers and clover stolon units. Proportion of clover in ingesta samples was consistently smaller than in the pasture, whereas plant observations showed similar frequency and severity of defoliation of grass and clover except in December, when clover was defoliated more severely. Observations on pasture structure indicated that clover foliage occurred lower in the canopy, and was grazed closer to the soil level, than grass leaves. Therefore, despite the evidence on diet composition, the results are interpreted as indicative of active selection for clover by the deer. The results are compared with published evidence on diet selection by grazing sheep. Keywords diet selection, deer, ryegrass, white clover, defoliation frequency, defoliation severity