Preference for different pasture grasses by horses in New Zealand

In New Zealand, grazed pasture is the primary nutrient source for equines, but little is known about equine grass preferences. A study to identify preferred grass species and/or cultivars (here on referred to as grasses) by horses was conducted in a 0.62 ha paddock containing 22 different test grasses. The grasses tested were planted in 6 x 3 m plots with four replicates of each species/cultivar. Four mature mares 527± 38 Kg, mean age 9 ± 3 years, were grazed on the trial plots for a total of five days during May 2007. Grass preference was quantified by; direct DM utilisation (prevs post-grazing dry matter cuts), pastureprobe measurement and visual assessment through photographs. Grass preference was similar for each method used to quantify utilisation (r 2 =0.73 – 0.76 P<0.0001). The six grasses most preferred by horses were all tetraploid ryegrasses (DM utilisation 74% (inter quartile range 67-81%). Least-preferred grasses were Yorkshire fog and Cocksfoot (DM utilisation down -0.9 to -14%). Hot water soluble carbohydrate and digestible organic matter in the dry matterwere the best predictors of grass preference. There was no significant effect of endophyte status (High, AR1, and Nil) on pasture preference during late autumn.