Digestive System Of Poultry 6e451d

STUDY ON DIGESTIVE SYSTEM OF POULTRY Digestive system in a chicken 

Birds have a relatively simple monogastric digestive system, somewhat similar to that of pig or man

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Birds, like humans, must depend on enzyme secretions to aid in breaking down complex molecules to simpler nutrients that can absorb

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Digestive system comprises alimentary tract/canal and accessory organs (liver, pancreas, spleen and gallbladder)

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These organs serve the same functions as in mammals, i.e. intake of food, storage, digestion, absorption and elimination of body waste

The brief description of the digestive organs in chicken and their functions are given below: Once food is eaten, it must be broken down into its basic components. This is done through both mechanical and chemical means:  Mechanical action typically involves chewing, but since birds don’t have teeth other mechanical methods are used.  Chemical action includes the release of digestive enzymes and fluids from the stomach, pancreas and liver. A. Alimentary tract 1. Mouth  No lips and teeth  A horny structure called beak present (upper and lower beak)  There are a little taste buds in tongue  Salivary gland present and secrets mucous which lubricate feed particles for easy swallowing 2. Esophagus  The esophagus or gullet is distinguished by its enormous expansibility  Food es from the mouth through the esophagus to the crop and onwards 3. Crop  The crop is an enlargement of the esophagus  Temporary storage and softening the food

 Food is gradually sent to the stomach as needed by concentration of the walls of the crop Figure 1. Model showing the internal organs of the female chicken

4. Proventriculus  The proventriculus or glandular stomach or true stomach of a bird is a relatively small enlargement at the end of the esophagus  Receives food from crop and secrets an enzyme pepsin, which aids in protein digestion and HCL which initiates the breakdown of seed coats & alter pH of the food to about 2.5 in chicken

 Digestion of food takes place in the proventriculus (little, if any) 5. Gizzard/ventriculus  Gizzard is located just back of the proventriculus and called mechanical stomach or muscular stomach  The gizzard breaks down ingested feed into smaller digestible fraction  Probably some gastric digestion takes place in gizzard  The chief function of the gizzard is to grind or crush food particles 6. Small intestine  It comprise duodenum, jejunum, ileum  It makes the digestive tract from the gizzard to the caeca  It is about 5 feet long in adult chicken  The digestive and absorptive processes in the small intestine are extremely rapid, a chicken can digest and absorb a full meal in less than 3 hours  Besides its digestive function, the small intestine also acts as an organ of absorption of the feed ingredients in simpler form Figure 2. Labeled photograph of the digestive tract of a chicken

7. Duodenum  Placed in the section of the small intestine which forms a fold immediately after the digestive canal leaves the gizzard, this loop, or folds of the duodenum, which s the pancreas  Gastric digestion, together with some pancreatic digestion, takes place in the duodenum 8. Large intestine  It comprises caeca, colon, rectum  Despite the name, the large intestine is actually shorter than the small intestine.  It lies between the junction o the caeca and extends for a short distance up to the exterior opening of the cloaca  The rectum of adult chicken is usually not more than 3 or 4 inches long  The cloaca is a chamber to the digestive, urinary and reproductive ages, which extends at the vent  The urine is discharged into the cloaca and excreted with the faces

 White pasty materials in chicken droppings is largely uric acid that has precipitated from urine

Figure: Droppings of chicken 9. Caeca (plural form; singular = caecum):  Caeca are two blind pouches, located at the junction of the lower intestine and large intestine (rectum)  Caeca are usually 4 to 6 inches long and are usually filled with faecal materials  They also aid in digestion of fiber  Some absorption may also take place in caeca

B. Accessory organs 1. Pancreas  Lying between the folds of the duodenum  This organ is relatively longer in birds than in mammals  It secrets a fluid known as pancreatic juice, that contains proteolytic, amylolytic and lipolytic enzymes which hydrolyse proteoses, peptones, starches and fats  The pancreas also secrets insulin to regulate sugar metabolism 2. Liver  This is a large, several lobed, dark red organ and largest gland in the body  The bile is produced in the liver and is conveyed to the lower end of the duodenum by two bile ducts

 The presence of food in the duodenum causes the gallbladder to contract and employ its bile into the intestine  The main function of bile is to emulsify fats so they will enter into solution to be digested 3. Spleen  This round reddish body is found near the liver  It is usually 0.25 to 0.5 inches diameter  Its functions is little unknown  Some authorities believe that white corpuscles of the blood accumulated in the spleen are rebuilt or cast from the body.