If a horse is overfed, especially with excessive amounts of rapidly fermentable feeds like starch from grains, the undigested excess feed escapes primarily into the cecum and large colon. These are parts of the hindgut where microbial fermentation occurs. When too much starch or feed reaches these organs, it can overwhelm the microbial populations, leading to gas accumulation, changes in gut pH, and digestive upset such as colic
. The small intestine is the main site for nutrient absorption, including starch digestion, but it has a limited capacity. Excess starch that is not absorbed here passes into the cecum and colon, where microbial digestion produces gaseous byproducts that can cause discomfort and health issues if excessive
. Thus, the excess feed escapes into the cecum and large colon when a horse is overfed
