The influence of sward characteristics on the herbage intake of grazing calves

Abstract

Summary Experiments were carried out at the Grassland Research Institute, U.K. (Expt 1) and the Universidad Central de Venezuela, Maracay (Expt 2), to study the influence of sward characteristics upon the herbage intake of young grazing cattle. In both studies the animals were strip-grazed in small groups on a series of plots, at a generous herbage allowance. The digestibility of the herbage ingested exerted a dominant influence on herbage organic matter (OM) intake, which increased at a constant rate as organic matter digestibility (OMD) increased throughout the range observed, 55–81% in Expt 1 and 53–63% in Expt 2. Intakes were similar in the two experiments at 60–65% OMD, but the rate of decline with decreasing digestibility was much greater in Expt 2 than in Expt 1. Intake was affected to a small extent in Expt 2 by the weight of herbage, the proportion of green material, and the extended height of the sward. In Expt 1 the intake from plots of primary growth was approximately 10% greater than that from secondary growths at equivalent digestibility and crop weight. The implications of these observations to techniques of grazing management are discussed.