THE INFLUENCE OF SPRING GRAZING MANAGEMENT ON PASTURE QUALITY

Abstract

Six grazing treatments, consisting of an intensity comparison (hard, medium and lax) at a 14.day regrowth interval, and a frequency comparison (regrowth intervals of 7, 14, 21 and 26 days) at the medium intensity, were imposed over 12 weeks during spring (treatment period). Subsequent pasture performance was assessed over a further 12 weeks during summer (post-treatment period). By the end of the treatment period two groups of wards were apparent. Compared with the other wards. Lax and Medium swards at regrowth intervals of 21 and 26 days were characterised by greater total, green, ryegrass reproductive stem and dead herbage mass and lower proportion of leaf. During the post-treatment period reproductive stem senesced and these wards contained greater levels of dead herbage. These swards also had lower leaf accumulation during the treatment period, though leaf accumulation was lower only on lax grazed swards during the post-treatment period. On high-fertility, ryegrass-dominant pastures hard grazing was not required to maintain pasture quality, as this occurred also under the medium grazing intensity (residual sward height 6-6 cm) provided the interval between grazing was 14 days or less (pregrazing ward height of 20 cm). It may be expected that herbage intake and animal performance on lax and infrequently (21 and 26 days) grazed swards would be reduced because of both lower leaf accumulation and greater dead herbage mass especially over the summer. Keywords: Pasture quality, ward characterisics, grazing frequency, grazing intensity, leaf accumulation, herbage mass.