Assessing quantity and quality of grazed forage on multi-species swards

摘要

Quantification of herbage intake by grazing livestock and estimation of forage quality of grazed herbage can be expected to be more difficult in multi-species swards than in simple species mixtures. The effect of sward composition (grass-dominated anddiverse) on the indirect estimation of forage uptake and quality was investigated in a grazing experiment with sheep and cattle as grazer species. Standing biomass was quantified using a double-sampling technique analysed for crude protein and acid detergent fibre. Contrary to expectations, there was no evidence for a systematically higher difficulty of estimating quality and quantity of standing biomass in diverse swards. Estimates of herbage intake strongly varied depending on the degree of specificity of the chosen calibration model for standing biomass against sward height, but without a consistent sward-type effect. Higher sample numbers were necessary for precise calibration models of standing biomass than for precise estimates of herbage quality.