Non-Ruminants+-+Pigs

=Non-Ruminants - Pigs=

Pre-Small Intestine (Group 3 - Teal K)
Pre- Small Intestine in pigs includes three different parts including the mouth, oesophangus, and the stomach: Mouth & Oesophangus: This is the British spelling, we usually spell it esophagus, just FYI. The mouth serves a valuable role not only for the consumption of food but it also provides for the initial partial size reduction though grinding. While teeth serve the main role in grinding to reduce food size and increase surface area, the first action to begin the chemical breakdown of food occurs when feed is mixed with saliva. There are three main salivary glands, which include the parotid, mandibular and sub-lingual glands. Saliva secretion is a reflex act stimulated by the presence of food in the mouth. The amount of mucus present in saliva is regulated by the dryness or moistness of the food consumed. Thereby in a dry diet, more saliva mucus is secreted while in a moist diet, only an amount to assist with swallowing is secreted. Saliva generally contains very low levels of amylase, the enzyme that hydrolyses starch to maltose. The contribution of digestive enzymes from saliva is minor but still noteworthy. Once food is chewed and mixed with saliva, it passes though the mouth, pharynx and then the oesophagus to the stomach. Movement though the oesophagus involves muscle peristalsis, which is the contraction and relaxation of muscles to move the food. Stomach: The stomach is a muscular organ responsible for storage, initiating the breakdown of nutrients, and passing the digesta into the small intestine. The stomach has four distinct areas which include the oesophageal, cardiac, fundic and pyloric regions. The oesophageal region is located at the entrance of the stomach from the oesophagus. This region of the stomach does not secrete digestive enzymes but has significance in that this is where ulcer formation in pigs occurs. Irritation in this area due to fine particle size, stress or other environmental factors can contribute to ulcer formation in swine. Once food passes though this region, it enters the cardiac region. In the cardiac portion of the stomach, mucus is secreted and mixed with the digested food. Food then passes into the fundic region which is the first major portion of the stomach that begins the digestive process. In this region, gastric glands secrete hydrochloric acid, resulting in a low pH of 1.5 to 2.5. This reduced pH kills bacteria ingested with the feed. Other secretions in this region are present in the form of digestive enzymes, specifically pepsinogen. Pepsinogen is then broken down by the hydrochloric acid to form pepsin, which is involved with the breakdown of proteins. Finally the digesta moves to the bottom of the stomach, which is the pyloric region. This region is responsible for secreting mucus to line the digestive membranes to prevent damage from the low pH digesta as it passes to the small intestine. The phloric sphincter regulates the amount of chyme (digesta) that passes into the small intestine. This is an important function not to overload the small intestine with chyme so proper and efficient digestion and absorption of nutrients occurs. In addition, once the chyme leaves the stomach, the material is quite fluid in consistency.

Small Intestine (Group 3 - Sarah L)
Some factors that can have an affect on the digestion and absorption in the small intestine of pigs are mode of ingestion, digestibility, and contact surface. Weaning can have a critical impact on the changes of structure and function of the small intestine in pigs. It was shown that histological changes were induced in the mucosa of the small intestine of piglets after weaning. If proper diets weren’t administered after weaning took place, a decrease in villi height could be seen, which means less surface area and absorption of materials. Most definitely. Any type of stress can reduce the surface area and functionality of the SI. Pigs can have small intestines that reach up to twenty meters in length and can account for one-third of their whole gastrointestinal tract volume. Pigs (and other mammals) have a small intestine that consists of three parts: the duodenum, the jejunum, and the ileum. The small intestine also consists of multiple layers. One of these layers is called the epithelium, which contains villi (projections) that consist of intestinal cells called enterocytes. Connective tissue makes up another layer of the small intestine. Nerves, blood, and lymphatic vessels are all considered connective tissues. There is additionally a smooth muscle layer that aids in involuntary peristalsis. There is also an external layer, which provides support and protection. The first portion of the small intestine is the duodenum. The duodenum can easily reach up to twelve inches in length in swine. This portion is the active site of digestion. This is where secretions from the pancreas are added from the pancreatic duct. These secretions contain some active enzymes and zymogens (inactive enzymes). The zymogen Trypsinogen is activated by Enterokinase, and activates it into Trypsin. The zymogen Chymotrypsinogen is activated by Trypsin and activated into Chymotrypsin. The zymogen Proelastase is activated by Trypsin and activated into Elastase. The zymogen Procarboxypeptidase A is activated by Trypsin and activated into Carboxypeptidase A. The zymogen Procarboxypeptidase B is activated by Trypsin and activated into Carboxypeptidase B. All of these enzymes digest protein. Other enzymes that come from the pancreas are Pancreatic Lipase (which digests lipids) and Pancreatic Amylase (which digests starches). Enterocytes in the intestine make active enzymes, specifically Maltase (digests maltose), Sucrase (digests sucrose), and Lactase (dissolves lactose). Bile from the bile duct (specifically bile salts) helps emulsify lipids and transport lipids through the small intestine. Cholesystokinin, like bile, is a digestion aid, and is stimulated by fat and protein entering the duodenum of the small intestine. It causes contractions in the pancreas and gall bladder, and these contractions help squeeze out the pancreatic juices and bile. The next portion of the small intestine is the jejunum, which is the largest part of the gastrointestinal tract. This is where villi are the longest, which explains why this is the portion where most of the nutrient absorption takes place. The last part of the small intestine is the Ileum. Not much absorption takes place here due to the fact that the villi are very short and there is not much surface area.

Large Intestine (Group 3 - Ashley G)
The large intestine is the site where absorption is completed. The large intestine begins with the cecum, which is rather large in the pig. The cecum is a blind pouch at the junction of the small and large intestines. It facilitates microbial digestion of fibrous carbohydrates. The cecum is the site for the production of volatile fatty acids by microbes. These VFA's are used for energy, and are absorbed through the cecal wall. The cecum is also the site for synthesis of B-vitamins by microbes. The last of absorption takes place here through these methods and the bolus is passed via peristalsis to the colon. The colon is flat, with no villi. It contains cuboidal and goblet cells. Goblet cells secrete mucous to help the absorbed bolus transform to feces. The colon is the last part of the gastrointestinal tract, and performs some of the same tasks as the cecum such as microial digestion, VFA synthesis, B-vitamin synthesis, and vitamin K. The last of water reabsorption takes place here and the remaining material is concentrated to feces. The colon has a slower rate of passage than other GIT organs. The last part of the large intestine is the rectum. Undigested material is fully formed into feces, which also consists of dead bacteria, sloughed cells and extra fluid.

Post Large Intestine (Group 3 - Candace H)
The anus is the last part of the alimentary tract in pigs and controls the exit and some of the formation of feces. Feces consist of water, undigested or unabsorbed feed, dead and sometimes alive bacteria, dead or sloughed cells, and other fluids.