Poultry Digestive Anatomy & Physiology 2024 PDF

Poultry Digestive Anatomy & Physiology Mouth and Esophagus Prehension is done through the beak. palate is incompletely fused : choanal cleft the tongue lacks musculature and is not much more than a bone (entoglossal bone) covered with a thick, cornifined mucous membrane. Esophagus...

Poultry Digestive Anatomy & Physiology Mouth and Esophagus Prehension is done through the beak. palate is incompletely fused : choanal cleft the tongue lacks musculature and is not much more than a bone (entoglossal bone) covered with a thick, cornifined mucous membrane. Esophagus features a distensible dilation called the crop or ingluvies. 1. a + b: cartilagenous os entoglossum 2. glandulae linguales (caudales) 3. linguales 4.cornified stratified squamous epithelium Mouth has many salivary glands :  Maxillary – in the roof of the mouth  Palatine – on either side of the nasal opening in the roof of the mouth  Apheno-pteryoid glands – in the roof of the pharynx on each side of the common opening for the eustachian tubes  Anterior sub-mandible glands – in the angle formed by the union of the upper and lower beaks or mandibles  Posterior sub-mandibular glands  Lingual glands – in the tongue  Crico-arytenoid glands – around the glottis  A small gland in the angle of the mouth  The oesophagus is wide and is capable of being significantly stretched. It connects the mouth region to the crop in close association with the trachea. The crop is a large dilation of the oesophagus located just prior to where the oesophagus enters the thoracic cavity. The crop provides the capacity to hold food for some time before further digestion. This capacity enables the bird to take its food as “meals” at time intervals but permits continuous digestion. Inside the thoracic cavity, the oesophagus enters or becomes the proventriculus which is a very glandular part of the digestive tract (often called the glandular stomach).  The wall of the oesophagus is composed of four layers of tissue like any other animals : mucosa, submucosa, muscularis and serosa  Proventriculus The glandular stomach, or proventriculus, is relatively small and tubular. The wall is very thick and is composed of five layers: Outer serous membrane Muscle layer composed of three separate layers:  Two thin longitudinal layers  Thick circular layer  Layer of areolar tissue containing blood and lymph vessels Thick layer composed mainly of glandular tissue Sub mucosal Mucous membrane  Simple single glands group to form lobules each of which converges into a common cavity near the surface. The cavities converge to form a common duct that leads to the surface through the apex of a small papilla. These glands produce a number of juices or enzymes that are used in the digestion or breaking down of food into its constituent nutrients. The mucous membrane is raised into folds and between these folds are numerous simple tubular glands that produce hydrochloric acid as well as lymphoid tissue.  Gizzard The muscular stomach or gizzard is located immediately after the proventriculus, partly between the lobes and partly behind the left lobe of the liver. Surface is covered by a glistening layer of tendinous tissue which is thicker at the centre and becoming thinner towards the edges. Under this outer layer there are located very powerful masses of red muscle. The highly keratinized mucosa on the inside of the gizzard, the cuticle, forms a thick, leathery sheet.  The gizzard almost always contains quantities of hard objects such as gravel or other grit that aids in the disintegration of food, which is the primary function of the gizzard. The gizzard mucosa consists of a number of layers of tissues, some of which contain straight tubular glands. The innermost layer is a strong, flexible skin that is able to withstand the potentially damaging effects of the muscular action grinding the food often in the presence of stones or other insoluble material. 1.koilin 2.mucosa 3.submucosa 4. muscularis The small intestine The small intestine begins at the exit from the gizzard and ends at the junction of the small intestine, caeca and colon. It is relatively long and has a constant diameter. Of the three parts of the small intestine only the duodenum can be easily observed. No clear demarcation between the jejunum and ileum. Produces a number of enzymes involved in the digestion process. Site of much of the digestion & the absorption of feed. Villi are present to increase the surface area & for absorption.  Duodenum After the duodenum the small intestine forms a coil and is suspended from the dorsal wall of the abdominal wall by a thin membrane called the mesentery. Pancreas lies between the arms of the loop and is attached to, and actually holds together, each arm of the duodenum. Lymphoid tissue in the duodenum is very plentiful and is usually located in the corium they collect the lymph and the lymph vessels transport fluid Bile ducts from the gall bladder that are attached to the liver and two to three pancreatic ducts enter the small intestine by a common papilla at the caudal end of the duodenum.  Jejunum and the ileum The jejunum and the ileum, together can about 120 cm long. commence at the caudal end of the duodenum where the bile and the pancreatic duct papilla are located and terminates at the ileo-caecal-colic junction. This junction is where the small intestine, the two caeca and the colon all meet. This portion of the small intestine is similar in structure to the duodenum except that:  It is suspended in the mesentery  The villi are shorter  There is less lymphoid tissue  Meckel’s Diverticulum : embryonic yolk sac attachment  Large intestine The large intestine is very short. Prominent ceca are present. Ends at the Cloaca. Water and electrolyte absorption take place.  Caeca The two caeca or blind pouches are about 16-18 cm long in the adult. They extend along the line of the small intestine towards the liver and are closely attached to the small intestine along their length by the mesentery. Each caecum has three main parts:  A narrow base with thick walls arising at the ileo- colic-caecal junction  Middle part with thin walls  The wide blind apex with fairly thick walls  The structure of the caeca :  Serous membrane  Outer longitudinal muscle  Circular muscle  Inner longitudinal muscle forming the muscularis mucosae of the mucous membrane  Cloaca The large intestine terminates in the front part of the cloaca. The cloaca is a tubular cavity opening to the exterior of the body and is common to the digestive and urogenital tract. The structure of the cloaca is very similar to that of the intestine except that the muscularis mucosa disappears near the vent. The Bursa of Fabricius is located immediately above the cloaca of young birds but disappears when the birds have reached approximately one year old.  It divides into three chambers, each separated by a constriction not readily defined: The copradaeum – a continuation of the colon-rectum. The urodaeum – middle part into which the ureters and genital ducts open. The proctodaeum – opens to the exterior of the vent. Birds less than one year old have a dorsal opening leading into the blind, rounded sac – the bursa of fabricius