The first thing many owners may worry about with respect to horses eating frosty/frozen grass is that it will cause colic due to the temperature. This really isn’t a concern. Whilst there is an increase in colic in cold weather, this is almost entirely due to impaction colic due to reduced water intake (horses drink less water in winter when the water is cold than if it’s warmed). If we think about what happens when a horse eats cold grass, the grass is rapidly warmed once in the mouth and then further warmed as it travels down the oesophagus to the stomach. By the time it is in the stomach, its at the same temperature as the rest of the body, and it still had a long way, both in time and distance, before it gets to the hindgut. So cold grass will not cause colic due to temperature.
However, when the grass is stressed, for example, by cold, sugars made during the day remain in the blades (leaves), which means the sugar content is higher. This can be an issue for those managing laminitic prone horses and ponies. Therefore, if overnight temperatures are below 5°C, there is a risk
for high sugar content, especially if days are also sunny. So, if you have a horse or pony at risk its best to limit grazing or offer hay or haylage in the field when temperatures fall below 5°C overnight.
So the short answer is yes for most horses and ponies but avoid or limit access to pasture when night-time temperatures are below 5°C, especially when combined with sunny days for horses and ponies prone to or at risk of laminitis.
