The effect of rotational grazing by either calves, cows, lambs or ewes on the removal of herbage contaminated with gastro‐intestinal parasite larvae around cattle faecal pats

Abstract

Faeces from calves infected with gastro‐intestinal nematodes were deposited in 12 paddocks during autumn and spring 2004 in the Waikato region, New Zealand. Individual paddocks were grazed three times after each faecal deposition, by calves, cows, lambs or ewes for 3 days, to similar herbage dry matter (DM) residuals. Before and after each day of grazing, herbage DM was measured within 10 cm wide concentric zones, out to 50 cm from the centre of faecal pats. Sheep grazed to lower residuals than cattle out to 20 cm from the centre of pats for the first grazing around autumn pats (P < 0.001) and for three grazings around spring pats (P < 0.01), and this was inversely related to faecal pat disappearance. In order to maximise the removal of herbage around faeces, and therefore the likely removal of parasite larvae, pasture grazed by infected cattle should have at least one subsequent grazing by sheep, with further sheep grazings if more than 10% of the initial cattle faecal DM remains. The number of grazings required to produce safe pastures was more dependent on the season of faecal deposition and grazing interval than on the type of animal they were grazed with.

Keywords:

• Cooperia
• faeces
• gastro‐intestinal nematodes
• grazing
• Ostertagia
• Trichostrongylus