Forage composition fluctuates depending on the time of day. In theory, dry matter intake (DMI) should increase throughout the day as nonstructural carbohydrates (NSC) increase.
Researchers at North Carolina State University set out to test this theory. The experiment measured equine forage intake during morning (AM) and afternoon (PM) grazing periods. Six light horse breed geldings were used and randomly allocated into one of two groups: an AM or a PM grazing treatment for 14 days. After the first 14 days, horses were switched to the opposite treatment for an additional 14 days. Morning treatment groups were grazed from 7:00 a.m. to 1:00 p.m. and PM groups were fed from 12:30 p.m. to 8:30 p.m. Horses were grazed on tall fescue pastures. Horses had higher intake rates in the PM grazing sessions compared to the AM sessions.
These results confirm previous beliefs that horses increase their DMI throughout the day, likely in response to increases in NSC. However, caution should be taken when grazing horses, especially horses prone to laminitis, on grasses high in NSC in the afternoon hours.
This article was summarized by Beth Allen, University of Minnesota. You can sign up to receive the University of Minnesota's horse newsletter online.