How are the sacs formed in poultry?

Not only domestic birds, but most living birds have bursaic sacs.

It's just that some birds have well-developed sacs, some are underdeveloped.

So when did birds first start to have sacs? According to the discovery of ancient bird fossils found by Chinese scientists in Liaoning, among the bird fossils about 100 million years ago, the earliest bird sac has been found.

The bursa is the esophagus of birds.

The latter part of the food is temporarily stored in the bulk. Food is moistened and softened in the sac before being fed into the forestomach and gizza for digestion. The sacs are single, such as chickens, or in pairs and transversely expanded, such as doves.

The sac wall of the musk pheasant is muscular, which can play a certain mechanical grinding role on the rough leaves stored in it. Ducks and geese do not have a bursal sac, but the esophagus is slightly spindle-shaped in the area. During the brooding period, the pigeon's sac produces milk, called "pigeon milk", which is used to feed the pigeon.

There is no consensus on the appearance of the sac. Scientists believe that the appearance of the bursa appears with the degeneration of the teeth of birds, the appearance of beaks, and the enhancement of digestive function. Since the bursa is more developed in grain-eating and fish-eating birds, and smaller in insectivore, carnivorous birds, scientists believe that birds are energy-intensive animals that need a well-developed digestive system.

to provide the energy needed for flight. When birds' teeth deteriorate, they rely only on their stomachs to digest unchewed, indigestible cereals.

It takes a long time and has insufficient ability to absorb nutrients, so the posterior esophagus has evolved to enlarge the posterior part of the esophagus to temporarily store food, and allow food to be moistened and softened in it, so that the stomach can digest food quickly.

and provides energy to the body.

The appearance of the sac reflects the progress and development of birds from primitive to mature.

The digestive system of birds.

How are vegetarian sacs formed in poultry? I don't know.

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The digestive organs of poultry include beak, mouth, pharynx, esophagus, bursa (ducks and geese are called esophageal bulge), glandular stomach, muscular stomach, small intestine, cecum, large intestine, rectum, cloaca, liver, pancreas, etc.

2. Poultry has no teeth, food is swallowed directly with the help of the tongue without chewing after ingestion of the mouth, although there are salivary glands in the mouth, but the secretion of saliva is not much, and the main component is mucus, containing a small amount of salivary amylase, so the digestion of saliva is not large.

Because there are a large number of microorganisms living in the bursa or esophageal bulging part, the feed is fermented and decomposed here, a small part of the products are absorbed by the bursal wall, and the remaining most of the fermentation products are further digested and absorbed in the back of the digestive tract.

The sac shrinks so that food passes from the bursa into the glandular stomach. The size of the glandular stomach is small, the food stays for a short time, and the digestion of gastric juice is mainly carried out in the muscular stomach; And because the glandular gastric mucosa lacks master cells, the gastric juice (pepsinogen and hydrochloric acid) of poultry is secreted by its parietal cells. In addition to giving full play to the digestion of gastric juice in the muscle and stomach, the solid muscles of the muscle and stomach and its solid corneum membrane, a certain number of sand grains contained in the muscle and stomach, and its rhythmic contraction make the feed particle size smaller, which is helpful for digestion.

The digestive juices of the poultry intestine do not contain enzymes that break down cellulose, and the other components are roughly the same as those of monogastric mammals, and a variety of enzymes work together to degrade the corresponding nutrients in the feed. The absorption of feed nutrients by poultry is mainly carried out in the small intestine, but the ratio of intestinal length to body length of poultry is smaller than that of mammals, and the feed stays in the intestine for a shorter time, and many nutrients are excreted with feces without full digestion and absorption.

The digestive system of poultry is simple, the digestive tract is short, the ratio of body length to the length of the digestive tract is about 1 4, the length of the intestinal tube of ducks and geese is about 4 5 times the length of the body, while the length of cattle is 20 times, and the pig is 14 times. Therefore, the feed passes through the digestive tract of poultry faster, digestion and absorption are incomplete, and the food eaten can be excreted from the body after about 4 5 hours. The digestive tract of the goose empties faster, the muscles and stomach are developed, accounting for more than 1 2 of the weight of the gastrointestinal tract, and the feed generally only remains in the gastrointestinal tract for about 2 hours.

Poultry rely on the beak for feed, there are no teeth in the mouth, the bottom of the mouth is where the tongue is located, the number of typical taste bud cells on the tongue mucosa is small, the sense of smell is not developed, but the taste can be felt empirically; The salivary glands are underdeveloped, and the salivary glands in the mouth secrete saliva to moisten food; The feed is mixed with mucus secreted in the oral cavity and swallowed through the esophagus into the bursa for temporary storage, and then discharged into the stomach for digestion. The bursa does not secrete digestive juices, only secretes mucus to soften the feed, some of which bacteria and amylase are the feed becomes soluble, the esophagus of ducks and geese does not form a bursage, and the cervical esophagus can be spindle-shaped and enlarged, temporarily storing food.

The main anatomical features of rabbits; The main anatomical features of poultry. Main experiments on the morphological structure of the whole body bone of domestic animals.

1. The digestive system of birds is significantly shorter than that of mammals, which is also a reason for the frequent excretion of birds, but the shorter digestive system helps to reduce the weight of birds.

2. Digestive characteristics of birds.

The digestive system of birds includes the beak, mouth, esophagus, bursa, stomach, small intestine, large intestine, cloaca, etc. Others, such as the liver and pancreas, are also digestive organs.

Birds have no lips and no teeth and are replaced by hard beaks, the shape of which varies from species to species. The mouth of birds is only a passage for food, not chewing. The esophagus is elastic and the lower end is markedly enlarged to form a bursage, which is a staple feeding on insects or carnivorous birds, and the bursa is small or absent.

The bursa secretes some fluid, which softens food for digestion. During the brooding period, some birds can secrete milk from the bursa to feed the chicks. The stomach of birds is composed of a glandular stomach (anterior stomach) and a muscular stomach (gizzard), and the glandular stomach has a thick stomach wall that secretes a large amount of digestive juices; The stomach wall of the muscular stomach is made up of solid muscles, and the inner layer is attached to the yellow corneal membrane, which contains a certain amount of sand and gravel, which has the function of grinding food.

The small intestine is the main organ for digesting food and absorbing nutrients in birds. Carnivorous and insectivorous birds have short intestines and their faeces can be excreted from the cloaca at any time. Birds that feed on seeds and other plant-based feeds have long intestines that allow food to be fully digested and absorbed.

The posterior end of the bird's intestine is connected to the cloaca, which opens outside the body. Birds are very active, digestive and fast, and are very sensitive to hunger, so they need to consume a sufficient amount of feed at all times to meet their energy consumption needs. Improper feeding of caged birds is a major cause of death.

3. Birds also have a physiological characteristic, that is, its digestive system is particularly strong, and its ability to replenish energy is particularly large. Some birds, the day's food and its weight are equal. If the "engine" power of the bird is calculated per unit weight, the value is also very impressive.

For example, a pigeon weighs about 350 grams, and the actual power emitted is about horsepower, which is equivalent to horsepower per kilogram of body weight. And the average person works hard, the power is not enough horsepower, the best athletes, both hands and feet, in a short period of time, can only send out horsepower, according to the weight of 70 kilograms, the average weight per kilogram can only send horsepower, about 1 4 about the pigeon.

4. The digestive system of birds is very simple and straightforward, and the digestion process from eating to excreting waste will not take more than a day, so it will be discharged from the excrement.

It is possible to estimate the food that the bird has eaten or the activity it has carried out before. When the bird owner is accustomed to discerning the normal excrement of the bird, it is only a little bit present.

If there is a small abnormality, the bird owner can quickly detect it and take it to the veterinarian for testing.

Blood poured into the chicken when it was killed. FYI.

You can consult the problem of raising chickens on the breeding software - Somutong.

When you are full, your sac will become bigger.