Gastrointestinal tracts of a carnivorous hawk, an omnivorous chicken, and 4 herbivorous birds. There are twelve pairs of cranial nerves. Lingual papillae arrows are compactly distributed on the tongue, and large conical papillae arrowhead are scattered among them. Frogs benefit humans in many ways. Rico-Guevara and Rubega found that hummingbird tongues do not function like a pair of tiny, static tubes drawing up floral nectar via capillary action. C fetus , C hyointestinalis , C mucosalis , and C sputorum are usually resistant to the fluoroquinolones yet sensitive to cephalosporins. The crop evolved for birds that are typically hunted by other animals but need to move to the open to find feed.
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At the end of pyloric stomach a small constriction is present. It possesses a pyloric sphincter. Stomach is divided into a glandular proventriculus and posterior muscular gizzard. Gizzard acts like grinding apparatus. Stomach is divisible into cardiac, fundic and pyloric parts. Pyloric stomach contains pyloric valve. Intestine is differentiated into duodenum and ileum. Intestine very long and very much coiled because is a herbivorous animal Same structures are present.
But the bile duct and pancreatic ducts open separately into the proximal and distal ends of the duodenum respectively. A single rectal caecum is present. An ilio-colic valve is present at the junction of the small intestine and large intestine or colon. At the junction of these portions, a spiral shaped vermi form appendix is present. At the regular intervals of the colon shows pocket-like pouches - 'Haustra'. Colon shows longitudinal muscle folds taeniae'.
Cellulose enzyme is produced. Cloaca is common opening for digestive'and urinogenital ducts. It is divided into coprodaeum,urodaeum, and proctodaeum. Cloaca is large and divided into the same parts. On the dorsal side of the proctodaeum a thick walled blindsa"Bursa fabricii" is present. It becomes degenerated in the adult and is known as cloacal thymus.
Liver is bilobed gland. The right lobe has a gall bladder. Liver is bilobed dark red gland. Gall Bladder is absent. Separate bile ducts are formed. Liver is very large and consists of five lobes. Kupffer's cells are present in the liver. Gall Bladder is present.
Pancreas is a whitish gland present between stomach duodenum. Pancreas is a pink coloured gland present the loop of duodenum. Three pancre catic ducts open into the duodenum. Pancreatic duct opens into the duodenum. Gastric, intestinal glands are also present. Ticks are common on reptiles, and heavy infestations may result in anemia. Argasid ticks may cause paralysis, with muscle degeneration at the site of the bite. The transmission of green-lizard papilloma—associated virus, several hemogregarines, and the filarid worm Macdonaldius oscheri have been associated with ticks.
Ticks can transmit Ehrlichia ruminantium , the cause of heartwater, and consequently the importation of African reptiles has been controlled. Ticks can be removed manually or by using permethrin spray. Systemic antibiotics are often indicated because of systemic infections associated with multiple cutaneous bite wounds and, potentially, with transmission of pathogenic bacteria. Leeches have been found on the legs, head, neck, and in the oral cavity of a variety of turtles and crocodilians.
Chelonians frequently have cutaneous myiasis. Bot flies including Cuterebra sp create a cutaneous wound in which to lay their eggs, which hatch into bots that live in cyst-like structures until mature enough to leave the wound.
Treatment consists of slightly expanding the natural opening and manually removing the bot with a forceps. The wound is then flushed with povidone-iodine, chlorhexidine, etc, and an antibiotic ointment is instilled. Systemic antibiotics are indicated in reptiles that have multiple lesions. Cutaneous myiasis also occurs secondary to existing wounds, and maggots must be manually removed and the underlying lesion treated with topical and systemic antibiotics as needed. During heavy fly season, turtles often are housed indoors or with screens over their enclosures to offer some protection.
Ectoparasite infestations are best prevented by thorough screening and quarantine of all new animals entering a collection. The stress of captivity coupled with a closed environment predisposes to heavy burdens of parasites with direct life cycles. Every effort must be taken to rid reptiles of parasite burdens and the environment of intermediate hosts.
Pathogenic trematodes infect the vascular system of turtles and infect the oral cavity, respiratory system, renal tubules, and ureters of snakes. Chemotherapeutic agents have not effectively eliminated these parasites, although praziquantel has shown some promise.
Tapeworms are found in all orders of reptiles but are rare in crocodilians. Reptiles may act as the definitive, paratenic, or intermediate hosts for a large number of species. Although most species of tapeworms are generally nonpathogenic in wild reptiles, weight loss and death have been reported.
The complex life cycle of cestodes and restricted geographic range of intermediate hosts limit the number of cases in captive reptiles. When present, proglottids may be found around the cloaca, or typical cestode ova may be isolated from feces. Treatment is with praziquantel , repeated in 2 wk. Plerocercoids of the genus Spirometra may be found as soft swellings in the subcutis. These larval stages may be removed surgically.
Nematodes are found in all orders of reptiles, and several genera are important. Strongyloides spp frequently inhabit the intestinal tract of reptiles; larvae are seen in the respiratory tract and respiratory exudate. In snakes, the larvae have been seen within granulomas distributed throughout the body wall, suggesting that the larvae may be able to penetrate the skin. Overwhelming parasitism is common when poor hygiene results in highly contaminated environments.
Rhabdias and related species have been found in the lungs of a variety of snakes; embryonated ova may be found in the oral cavity and in lung aspirates. Embryonated ova and free larval forms may be seen in the feces. Larvae resembling Rhabdias also have been seen in the gingiva of snakes with stomatitis. Infections often are subclinical but may be associated with secondary bacterial pneumonia. In severe cases, death may result. Stomach worms of the genus Physaloptera are seen in lizards. Gastric ulceration may occur in severe infections.
Ova are elliptical and may be embryonated. Numerous snakes are infected by Kalicephalus spp. This hookworm, capable of transcutaneous infestation, prefers the upper GI tract and causes erosive lesions at sites of attachment. Ova are similar to those of Physaloptera spp. An understanding of the avian digestive system is essential for developing an effective and economical feeding program for your poultry flock and for recognizing when something is wrong and taking necessary actions to correct the problem.
An animal's body breaks down food through both mechanical and chemical means. Chemical action includes the release of digestive enzymes and fluids from various parts of the digestive system. After being released from food during digestion, nutrients are absorbed and distributed throughout the animal's body.
The chicken has a typical avian digestive system. Figure 1 shows a chicken digestive tract, and Figure 2 shows the location of the digestive tract in the chicken's body. As with most birds, a chicken obtains feed by using its beak.
Food picked up by the beak enters the mouth. Chickens do not have teeth, so they cannot chew their food. However, the mouth contains glands that secrete saliva, which wets the feed to make it easier to swallow.
The esophagus is a flexible tube that connects the mouth with the rest of the digestive tract. It carries food from the mouth to the crop and from the crop to the proventriculus. The crop is an out-pocketing of the esophagus and is located just outside the body cavity in the neck region see Figure 3. Swallowed feed and water are stored in the crop until they are passed to the rest of the digestive tract. When the crop is empty or nearly empty, it sends hunger signals to the brain so that the chicken will eat more.
Although the digestive enzymes secreted in the mouth began the digestion process, very little digestion takes place in the crop—it is simply a temporary storage pouch. The crop evolved for birds that are typically hunted by other animals but need to move to the open to find feed.
Occasionally, the crop becomes impacted, or backed up. This problem—called crop impaction, crop binding, or pendulous crop—can occur when a chicken goes a long time without feed and then eats too much too quickly when feed is available again. Crop impaction also can occur when a chicken free-ranges on a pasture of tough, fibrous vegetation or eats long pieces of string. With crop impaction, even if a chicken continues to eat, the feed cannot pass the impacted crop. The swollen crop also can block the windpipe, causing the chicken to suffocate.
The esophagus continues past the crop, connecting the crop to the proventriculus. The proventriculus also known as the true stomach is the glandular stomach where digestion primarily begins. Hydrochloric acid and digestive enzymes, such as pepsin, are added to the feed here and begin to break it down more significantly than the enzymes secreted by the salivary glands.
Two views of the proventriculus and gizzard from a chicken digestive tract. Jacquie Jacob, University of Kentucky. Consumed feed and the digestive juices from the salivary glands and proventriculus pass into the gizzard for grinding, mixing, and mashing. Inside of a chicken gizzard, with the internal lining removed.