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Food passes from the oral cavity into the [[oesophagus - Anatomy & Physiology|oesophagus]] and from here to the stomach. In evolutionary terms, various adaptations to the anatomy of the stomach reflect the digestive needs of the species based on their natural diet. The [[Ruminant Stomach - Anatomy & Physiology|ruminant stomach]] for example, is composed of 4 separate compartments; the rumen, the reticulum, the omasum and the abomasum. The first three compartments are adapted to digest complex carbohydrates with the aid of microorganisms which produce [[Volatile Fatty Acids|volatile fatty acids]] - the major energy source of ruminants. The last compartment, the abomasum resembles the simple [[Monogastric Stomach - Anatomy & Physiology|monogastric stomach]] of a carnivore in structure and function.  As a further adaptation, the [[Oesophageal Groove|oesophageal groove]] is present in newborn ruminants; it is a channel which directs milk from the oesophagus into the rumen, omasum and then abomasum, bypassing the reticulum.  

Food passes from the oral cavity into the [[oesophagus - Anatomy & Physiology|oesophagus]] and from here to the stomach. In evolutionary terms, various adaptations to the anatomy of the stomach reflect the digestive needs of the species based on their natural diet. The [[Ruminant Stomach - Anatomy & Physiology|ruminant stomach]] for example, is composed of 4 separate compartments; the rumen, the reticulum, the omasum and the abomasum. The first three compartments are adapted to digest complex carbohydrates with the aid of microorganisms which produce [[Volatile Fatty Acids|volatile fatty acids]] - the major energy source of ruminants. The last compartment, the abomasum resembles the simple [[Monogastric Stomach - Anatomy & Physiology|monogastric stomach]] of a carnivore in structure and function.  As a further adaptation, the [[Oesophageal Groove|oesophageal groove]] is present in newborn ruminants; it is a channel which directs milk from the oesophagus into the rumen, omasum and then abomasum, bypassing the reticulum.  

The stomach passes into the [[Small Intestine Overview - Anatomy & Physiology|small intestine]], which is subdivided into three sections; the [[Duodenum - Anatomy & Physiology|duodenum]], the [[Jejunum - Anatomy & Physiology|jejunum]] and the [[Ileum - Anatomy & Physiology|ileum]]. The small intestine recieves the ingested food from the stomach and is the main site of the chemical degradation and absorption of ingesta. Fats are exclusively broken down in this part of the alimentary tract. Carbohydrates and proteins that are not degraded in the small intestine are available for microbial fermentation in the large intestine. The wall of the small intestine produces enzymes for the digestion of protein, carbohydrate and fat. The [[Pancreas - Anatomy & Physiology|pancreas]] also produces digestive enzymes to aid this process. The [[Gall Bladder - Anatomy & Physiology|gall bladder]] stores bile which is produced in the [[Liver - Anatomy & Physiology|liver]] and emulsifies fats for digestion. Absorption in the small intestine is facilitated by ridges in the small intestine and by the presence of villi and microvilli.  

The stomach passes into the [[Small Intestine Overview - Anatomy & Physiology|small intestine]], which is subdivided into three sections; the [[Duodenum - Anatomy & Physiology|duodenum]], the [[Jejunum - Anatomy & Physiology|jejunum]] and the [[Ileum - Anatomy & Physiology|ileum]]. The small intestine receives the ingested food from the stomach and is the main site of the chemical degradation and absorption of ingesta. Fats are exclusively broken down in this part of the alimentary tract. Carbohydrates and proteins that are not degraded in the small intestine are available for microbial fermentation in the large intestine. The wall of the small intestine produces enzymes for the digestion of protein, carbohydrate and fat. The [[Pancreas - Anatomy & Physiology|pancreas]] also produces digestive enzymes to aid this process. The [[Gall Bladder - Anatomy & Physiology|gall bladder]] stores bile which is produced in the [[Liver - Anatomy & Physiology|liver]] and emulsifies fats for digestion. Absorption in the small intestine is facilitated by ridges in the small intestine and by the presence of villi and microvilli.  

The [[Large Intestine - Anatomy & Physiology|large intestine]] begins at the [[Caecum - Anatomy & Physiology|caecum]], and includes the [[Colon - Anatomy & Physiology|colon]], the [[Rectum - Anatomy & Physiology|rectum]] and the [[Anus - Anatomy & Physiology|anus]]. Water, electrolytes and nutrients are absorbed which concentrates the ingesta into faeces. There is no secretion of enzymes and any digestion that takes place is carried out by microbes. All species have a large microbial population living in the large intestine, which is of particular importance to the [[Hindgut Fermenters - Anatomy & Physiology|hindgut fermenters]] such as the horse. For this reason, hindgut fermenters have a more complex large intestine with highly specialised regions for fermentation. The volatile fatty acid products of microbial fermentation are absorbed in the colon.  

The [[Large Intestine - Anatomy & Physiology|large intestine]] begins at the [[Caecum - Anatomy & Physiology|caecum]], and includes the [[Colon - Anatomy & Physiology|colon]], the [[Rectum - Anatomy & Physiology|rectum]] and the [[Anus - Anatomy & Physiology|anus]]. Water, electrolytes and nutrients are absorbed which concentrates the ingesta into faeces. There is no secretion of enzymes and any digestion that takes place is carried out by microbes. All species have a large microbial population living in the large intestine, which is of particular importance to the [[Hindgut Fermenters - Anatomy & Physiology|hindgut fermenters]] such as the horse. For this reason, hindgut fermenters have a more complex large intestine with highly specialised regions for fermentation. The volatile fatty acid products of microbial fermentation are absorbed in the colon.