Preference, Yield, and Forage Nutritive Value of Annual Grasses under Horse Grazing

CORE IDEAS: Horses preferred winter wheat, annual ryegrass, and spring wheat. Annual ryegrass, spring oat, and winter barley were the highest yielding species. Spring oat, spring barley, and spring wheat had little to no regrowth. Winter wheat and winter rye consistently had higher forage nutritive values. Annual ryegrass can extend the grazing season or provide emergency forage for horses. Annual grasses such as oat (Avena sativa L.), wheat (Tricum aestivum L.), and barley (Hordeum vulgare L.) can serve as alternative forage but little research exists under horse (Equus caballus) grazing. The objectives were to evaluate annual cool‐season grasses for preference, yield, and forage nutritive value under horse grazing during the summer and fall in Minnesota. Spring‐planted grasses included spring barley, spring oat, spring wheat, winter wheat, and annual ryegrass (Lolium multiflorum L.). Summer‐planted grasses included the same five species plus spring forage oat, winter barley, and winter rye (Secale cereal L.). Beginning in June and September of each year, horses grazed grasses at a vegetative stage. Plots were mowed, allowed to regrow, and grazed again. Although spring oat, spring forage oat, and winter barley were often among the highest yielding grasses (≥3.0 Mg ha⁻¹), they were also among the least preferred grasses (≤32% removal). Annual ryegrass, winter wheat, and spring wheat were among the most preferred grasses (≥35% removal). Among these highly preferred grasses, annual ryegrass was typically higher yielding (≥2.7 Mg ha⁻¹), while winter wheat and spring wheat were among the lowest yielding species (≤4.7 Mg ha⁻¹). All grasses contained ≥130 g kg⁻¹ crude protein (CP), ≤610 g kg⁻¹ neutral detergent fiber (NDF), ≤220 g kg⁻¹ nonstructural carbohydrates (NSC), and ≥2.02 Mcal kg⁻¹ equine digestible energy (DE). Annual ryegrass appears to be a viable forage alternative to maximize yield, preference and forage nutritive concentration in horse pastures.