Abstract

Despite a perceived reliance of horses on pasture there are limited data on efficiency of pasture utilisation in equine production systems. The unique equine behaviour characteristics of highly selective browsing, combined with faecal avoidance, provide distinct grazing management challenges compared to those of ruminants. Data reported here show that faecal avoidance results in the establishment of lawns and roughs (overgrazed and poorly grazed areas, respectively) with it estimated that only 70% of the total pasture DM/ha on offer is utilised by horses. During spring, lawns contained more grass (74% vs 53%) and clover (5% vs 3%) and less weeds (2% vs. 11%) and dead matter (19% vs. 33%) than did roughs. Weanlings will start to graze roughs once the lawns are <1500 kg DM/ha. Roughs, however, will not be grazed within 1 m of a faecal pile. This translates to a lower pasture utilisation rate in weanlings and the biased grazing pattern means estimates of total pasture DM over-estimate the true available pasture DM. The relative proportion of pasture in lawns and roughs changes during grazing and prevents the application of a simple correction factor to estimate available DM. Broodmares had greater rates of pasture utilisation and less bias for consumption of pasture in areas of roughs than did weanlings.

CW, Rogers, EK Gee, PJ Back, S van Zon, RL Hirst, and WE Pomroy

New Zealand Journal of Animal Science and Production, Volume 78, Lincoln, 40-44, 2018