Digestion of Lipids occurs with the following enzymes :
Lipases break fats into glycerol and fatty acids Recall that large lipid globules must be first Emulsified into smaller units
Fibre is indigestible by equine as they lack the enzyme necessary to break the bonds which link fibre molecules together. It requires fermentation in equine hindgut where natural flora digests fibre and produces a biproduct which can be used as a source of energy for the horse. More on this later….
Absorption in the Small Intestine
All the chemical and mechanical phases of the digestion from the mouth through the small intestine are directed toward changing food into forms that can pass through the absorptive epithelial cells lining the mucosa and into the underlying blood and lymphatic vessels (lacteals). These forms are monosaccharides (glucose, fructose, and galactose) from carbohydrates; single amino acids , dipeptides, and tripeptides from proteins; and fatty acids , glycerol, and monoglycerides from triglycerides. Minerals and vitamins are absorbed unchanged.
Absorption occurs via diffusion, facilitated diffusion, osmosis, and active transport.
~ 90% of absorption occurs in the small intestine, 10% in the stomach and large intestine.
Large Intestine
7-8m long extending from the ileum to the anus. Structurally there are 4 major regions: Cecum - 1m long, capacity 30 - 35L Large colon – 3m long, capacity 75L Right ventral colon sternal flexure Left ventral colon pelvic flexure Left dorsal colon diaphragmatic flexure Right dorsal colon Small colon – 3m long, capacity 20L
Rectum – 20-30 cm, terminal opening of the rectum is the anus
Opening from ileum to cecum is guarded by the Iliocecal sphincter. Opening of the anal canal to the exterior is guarded by an Internal Anal sphincter of smooth muscle and an External Anal sphincter of skeletal muscle. A characteristic of the cecum & colon is the highly sacculated appearance. Teniae are longitudinal smooth muscle bands within the wall of the intestine on the dorsal, ventral, medial and lateral surfaces. These are ribbons of smooth muscle, when contracted created the typical bulging of the cecum. These gatherings of intestinal wall are called haustrae .
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