PASTURE UTILISATION AND ITS EFFECT ON HERBAGE QUALITY

Abstract

An existing grazing trial on an irrigated Wakanui silt loam at Lincoln College, Canterbury, was sampled at five consecutive grazings (January to July, 1983) to determine the effects of pasture utilisation on herbage composition and in vitro digestibility of regrowth. Rotational grazing of sheep at two stocking rates, high (27.5 ewes/ha) and low (17.5 ewes/ha), resulted in different levels of utilisation. Low utilisation (27%) produced a sward with a high dead material content (44%) and low in vitro digestibility of the whole sward (<70%). The high stocked sward (utilisation, 60%) had a greater percentage of green material (83%) but total green yields were only half those at the low stocking rate. The in vitro digestibility of the sward under the high stocking rate was Z-70%, mainly as a result of only a small proportion of dead material with low (46%) digestibility. Keywords: pasture utilisation, herbage composition, dead matter, green herbage yield, in vitro digestibility, stocking rate