The effect of continuous and rotational grazing of sourveld on the selection of plant fractions by Simmentaler heifers.

In a grazing trail conducted at the Kokstad Agricultural Research Station, the selection of six plant fractions by cattle grazing sourveld was investigated. Relations between the selectivity of the cattle and the dry matter digestibility (DMD) and crude protein (CP) content of these fractions were examined. The effects of continuous and six-paddock rotational grazing (each at 1, 0 and 2, 3 animals/ha) on selectively were examined. In general, cattle preferentially selected the glabrous foliar components, which constituted 31, 3% of herbage on offer and had the highest DMD (56%) and CP content (5, 77%) of grass fractions. With the exception of broad hairy leaves, rejection of the other components appeared to be primarily related to their lower nutritive value. Rotational grazing per se did not significantly decrease selectivity. In the heavily stocked, rotational grazing treatment cattle consumed a greater proportion of the stem fraction but rejected more of the hairy leaves than in the other treatments. It was thus concluded that cattle continued to graze selectively regardless of the grazing method or the stocking intensity.Keywords: cattle grazing; crude protein; digestibility; dry matter digestibility; grasses; grazing; herbage; kokstad agricultural research station; leaf fraction; leaves; oesophageal fistulas; protein; rotational grazing; selectivity; sourveld; south africa; stem fraction; stocking rate; trai