Effects of Gibberellic acid on pasture and animal production in winter

Abstract

Results are given of a series of field experiments in which Phalaris tuberosa subterranean clover pastures were sprayed with gibberellic acid during winter. The growth of Phalaris was initially stimulated to a marked degree. At considerable expense per acre, this increase in dry matter produced a temporary advantage in liveweight in both weaner sheep and pregnant ewes at a time of the year when the supply of normal pasture was low. Further effects on animal production are discussed in relation to food demands and the sequence of plant reactions to spraying treatment; these effects were adverse in the case of lambing ewes because pasture growth temporarily declined after the period of stimulation. Effects of gibberellic acid on the nutritive value and botanical composition of the pasture are also reported.