Grazing capacity, milk production and milk composition of kikuyu over-sown with annual or perennial ryegrass

Abstract

Kikuyu (Pennisetum clandestinum) is a highly productive pasture species that supports high stocking rates and milk production per hectare, but production per cow is low due to low nutritive value. The aim of this study was to determine the grazing capacity, milk production and milk composition of dairy cows grazing irrigated kikuyu over-sown with Italian (Lolium multiflorum var. italicum), Westerwolds (L. multiflorum var. westerwoldicum) or perennial ryegrass (L. perenne) during autumn. The grazing capacity of the kikuyu–ryegrass systems was lower during winter and autumn than during spring and summer, with the seasonal grazing capacity of the perennial ryegrass treatment more evenly distributed than that of the Italian and Westerwolds ryegrass treatments. The perennial ryegrass treatment had a lower butterfat and milk production per lactation than the Italian and Westerwolds ryegrass treatments, but had the highest milk solids and fat corrected milk production per hectare. The latter was a result of the higher annual grazing capacity achieved by the perennial ryegrass treatment. It was concluded that because kikuyu over-sown with perennial ryegrass supported a higher number of animals and had a more evenly distributed fodder-flow, it achieved higher animal production per hectare than kikuyu over-sown with annual ryegrass varieties.