Spring grazing & harvest date

The effect of simulated grazing on the yield and quality of multi-species swards for silage production

This experiment is determining the impact of the number of spring grazings on the yield and nutritive value of the grass crop when subsequently harvested for silage. The herbage treatments include intermediate or late heading perennial ryegrasses and a multi-species mix consisting of perennial ryegrass, timothy, red and white clover, chicory and ribwort plantain. Simulated spring grazing is applied with replicate plots receiving one, two or three simulated grazings between mid-March and early May. Plots are then managed as for silage production for the rest of the growing season. Primary growth silage harvests on replicate plots are in mid-May, late May and early June. The subsequent second and third harvest take place at 7 week intervals and the final harvest is in mid-November.

Prior to each harvest, a full botanical assessment is carried out in which species abundance and plant growth stage are determined. Herbage is cut using a Haldrup plot harvester before being chopped with a forage harvester. A sample of fresh herbage is taken from all plots to determine dry matter yield and chemical composition. Select treatments throughout the season are ensiled in laboratory silos to determine the effects of treatment on conservation characteristics and silage quality.