The rectum and the large intestine: how does digestion work?

Hi! Great question! 😊🐴

🥕The horse is what we call a hindgut fermenter. The large intestine is the biggest part of the horse's digestive system, and it is made up of the caecum and the colon.

🥕This is where water and most of the horse's energy from the feed are absorbed. Unlike the small intestine, there are no enzymes or bile of the horse's own to break the feed down. Here the work is done by micro-organisms (fungi, bacteria and single-celled animals).

🥕Feed usually takes 1 to 3 days to pass through the large intestine.

🌾The micro-organisms break down the cellulose in plant fibre, along with some of the starch left over from the small intestine. Their own metabolism produces fatty acids as a by-product, mainly butyric, acetic and propionic acid, which the horse can then convert into energy.

👾The horse also seems to absorb some of the protein released as the micro-organisms die off, but not in a large enough amount to make up for a shortfall of protein in the ration.

❤️‍🩹Look after the micro-organisms, the gut flora! There are huge numbers of them, but they are also sensitive. Stress, sudden changes of feed, infections and certain medications are all things that can quickly throw the gut flora out of balance. That can have serious consequences such as colic, laminitis or behavioural problems.

💩The rectum is the final stop, where water is absorbed and the droppings are formed.