Dr Tim Kempton, Stance Equine. All feeds contain carbohydrates. Carbohydrates include the fibre, and sugars and starch. The fibres are the STRUCTURAL CARBOHYDRATES that hold the plant up. These fibres are both digestible or indigestible. Look at your horse’s manure. Take some and wash it in a bucket. What you see is the indigestible fibre from the feed. Horse’s manure is drier than cattle because they do not digest fibre as well as cattle, and because they absorb more water from the hindgut.