Potential of intensive rotational grazing for control of ovine gastrointestinal nematodosis in a cool temperate environment with summer dominant rainfall

Abstract

To date there have been no reports of practical rotational grazing systems for the control of ovine gastrointestinal nematodosis in cool temperate climates, despite their success in the humid tropics. However there is anecdotal evidence that the intensive rotational grazing systems (such as "cell grazing") that are gaining in popularity in these regions, offer significant control. Intensive rotational grazing involves the use of large groups of animals at high stock densities moving through a series of 20 to 40 paddocks at a rate dependant on the amount of feed on offer and pasture growth rate (not based on rigid time periods). The grazing period generally ranges from 2-3 days with rest periods of 40-90 days, resulting in paddocks being rested for 90-95% of the year. The work contained in this thesis was conducted to investigate the merits of these claims. The unifying hypothesis was that intensive rotational grazing reduces faecal worm egg counts in sheep by interrupting the nematode lifecycle in its free-living stages and that the greatest effect will be on the blood-sucking parasite 'Haemonchus contortus'. The work was conducted on the Cicerone Project, a producer-led project comparing three different sheep management systems in the New England Region of Northern NSW. The three management systems were typical (TYP - moderate input, limited rotational grazing, graze periods average 53±0.1 days and rest periods average 78±10 days), high input (HI, high input, limited rotational grazing, graze periods average 40±0.1 days, rest periods average 65±8 days) and intensive rotational grazing (IRG, moderate input, short graze periods average 3±0.1 days, long rest periods average 108±4 days).