Understanding Poultry Digestion

Instead of asking “Why did the chicken cross the road?” poultry hobbyists may better ask, “How does the chicken chew its feed without any teeth?” Even without teeth, chickens have one of the most efficient digestive systems in the animal kingdom. Let’s take a look at how the poultry digestive system works.

Food is taken in with the beak, which is the perfect tool for pecking feed in crumble or pellet form, small grains, grass or insects. Chickens are omnivores – meaning that, in addition to a commercial feed, they can eat meat (grubs, worms, the occasional mouse) and vegetation (grass, weeds and other plants). A small bit of saliva and digestive enzymes are added as the food moves from the mouth into the esophagus.

From the esophagus food moves to the crop, an expandable storage compartment located at the base of the chicken’s neck, where it can remain for up to 12 hours. The food trickles from the crop into the bird’s stomach (proventriculus or gizzard) where digestive enzymes are added to the mix and physical grinding of the food occurs.

The gizzard is why chickens do not need teeth. It is a muscular part of the stomach and uses grit (small, hard particles of pebbles or sand) to grind grains and fiber into smaller, more digestible, particles.

From the gizzard, food passes into the small intestine, where nutrients are absorbed. The residue then passes through the ceca, a blind sack along the lower intestinal tract, where bacteria help break down undigested food. From the ceca, food moves to the large intestine, which absorbs water and dries out indigestible foods.

This remaining residue passes through the cloaca where the chicken’s urine (the white in chicken droppings) mixes with the waste. Both exit the chicken at the vent, the external opening of the cloaca.

And don’t think of chicken manure as “waste” to be disposed of…it makes a great fertilizer for your flower beds or vegetable garden. Because it is high in nitrogen, it is recommended to let it age for a bit in a compost pile before adding it to your gardens.

Tour the Poultry Digestive System

It is important to understand how a chicken or other fowl digests its food. Here’s a quick tour of how food moves through their digestive tract.

  • Mouth: It all starts here.
  • Esophagus (Gullet):Transports food from the mouth to the stomach.
  • Crop: A pouch in the esophagus used to store food temporarily before moving it on to the stomach.
  • Stomach (Proventriculus or “Gizzard”): Principally the organ where food is broken into smaller units. It has two parts: the proventriculus for storage and the gizzard. The gizzard is a muscular part of the stomach that uses grit to grind grains and fiber into smaller particles.
  • Small Intestine: Aids in digestion and nutrient absorption. Composed of the duodenum, jejunum and ileum.
  • Liver: The largest glandular organ in the body. Aids in the metabolism of carbohydrates, fats and proteins.
  • Ceca: Bacterial action in the ceca helps break down undigested food passing through the intestine. The ceca turns into the large intestine, which connects with the  cloaca.
  • Large Intestine: Functions primarily to absorb water, dry out indigestible foods and eliminate waste products.
  • Cloaca: Where the digestive, urinary and reproductive systems meet.
  • Urinary System: Consists of two kidneys and two ureters. The kidneys are located in the pelvic bones. They filter waste from the blood and pass it through the ureter to the outside via the cloaca/vent.
  • Vent: The external opening of the cloaca that passes waste to the outside.

Disease Prevention in Poultry

Nutritious feed, access to fresh, clean water, and adequate housing are important to the health of your flock. Good management and sanitation practices are essential as well. Proper ventilation in the brooder and coop will reduce moisture and disease organisms. Caked or wet litter should be removed as soon as it forms to keep the house clean and dry.

For most backyard poultry enthusiasts, diseases are rare as long as the flock doesn’t come into contact with other flocks. The most common disease for young, unmedicated flocks is coccidiosis, which is characterized by diarrhea, unthriftiness and some mortality. A medicated chick feed can help prevent coccidiosis.

A rigid sanitation program can help prevent parasites. If internal parasites become a problem, products to treat them are available from your feed dealer.

Check your flock daily to spot diseases or parasites so you can start treatment right away. For more information about identifying, preventing and treating poultry diseases and parasites, contact your local veterinarian. Your local feed dealer can help you choose the right feed to support the nutritional needs of your flock.

Types of Poultry

Once you decide to start raising fowl, it is important to select the right type of birds to suit your needs, environment, and desires. Below is a quick overview of the main types of birds available to most people.

Chickens

Many different breeds of chickens have been developed for different purposes. For simplicity, you can place them into three general categories: Laying, meat-producing and dual-purpose breeds.

  • Laying Breeds:
    • These breeds are known for their egg-laying capacity.
    • Popular laying breeds include the White Leghorn, Red Sex Link and Black Sex Link breeds.
    • A healthy hen will lay eggs for several years. Hens begin to lay at approximately 16–20 weeks of age and will lay between 20–23 dozen eggs the first year.
    • At 14 months, laying hens usually begin to molt, the process by which they drop their old feathers and grow new ones. No eggs are laid during this period.
    • After molting, hens will lay larger but fewer eggs per year (about 16–18 dozen).
  • Meat Breeds:
    • Meat-producing breeds are very efficient at converting feed to meat, producing approximately one pound of bodyweight for every two pounds of feed they eat.
    • A popular meat-producing breed is the Cornish breed. The Cornish game hen is a cross between the Cornish and the New Hampshire or Plymouth Rock breeds.
    • Meat-producing chickens are broad breasted and larger than the laying breeds.
    • They grow and feather rapidly and will weigh five pounds or more at eight weeks.
    • Broilers and fryers are butchered at 31/2 to 5 pounds, while a roaster is butchered at 6 to 8 pounds.
  • Dual-Purpose Breeds:
    • The dual-purpose breed is the classic backyard chicken. These breeds are hardy, self-reliant and fairly large bodied. Most lay large brown-shelled eggs.
    • Examples include Rhode Island Red and New Hampshire breeds.
    • Some laying and dual-purpose hens tend to get broody, which means they will want to sit on and hatch eggs. Because broody hens don’t lay eggs, egg production will be affected.

Turkeys, Game Birds and Other Poultry

Turkeys, geese, ducks and pheasants are often raised as pets or for their egg and meat-producing qualities. They also can make terrific projects for children to learn responsibility and animal husbandry skills. Your local feed dealer and extension agent are excellent resources for information on breeds and species that are appropriate for your goals and geographic region.

Care Tips for Healthy Hens

Raising layer hens is an investment in fresh, wholesome eggs. Your hens will perform best if they have room to live and roam, nutritious feed, fresh water, and a safe, comfortable coop to nest and roost.

Your coop should have a minimum of four square feet of space per hen, and one perch and one nest box for every four or five hens. Spread a 6-inch layer of shavings or sawdust on the floor to absorb droppings and give the birds a place to take a dust bath. Chickens tolerate temperature extremes but will suffer in cold winter drafts or stifling summer heat. Make sure the coop is free of drafts during the winter and well ventilated in the summer.

Protect your chickens from predators by keeping them penned within good, sturdy fencing and closing the coop door each evening after your flock goes to roost.

Because hens rarely find enough nutrients on their own for a complete, balanced diet, your choice of feed is important. Select one with the protein, vitamins and minerals they need to meet their unique nutritional requirements. Keep feed and fresh, clean water available at all times. Give your hens oyster shell or coarse-ground limestone to help maintain their calcium levels and grit to help them digest their food. An occasional treat of scratch grains will satisfy their pecking instincts and keep them busy.

How Much Heat Should Baby Chicks Have?

Baby chicks have the remarkable ability to find their ideal zone of warmth in the brooder and if you simply note your chicks’ positions, you’ll know whether the brooder temperature is too hot, not warm enough, or juuuuust right.

Temperature Correct

If the heat level is just right, chicks will be evenly spread throughout the brooder. With adequate food and fresh water, you’ll hear them making contented peeping sounds.

Temperature Too High

If your chicks are spread out around the perimeter of the brooder the temperature is likely too high. Raise the heat lamp another couple of inches and/or switch to lower wattage bulbs. The chicks will be silent and you may notice them panting and heads drooping.

Temperature Too Low

If the brooder is too cool, chicks will huddle together directly under the heat lamp. They will be noisy, a sign of distress. Lower the lamp closer to the floor of the brooder and/or put in higher watt bulbs.

Other Problems

Chicks huddled together in one spot on the perimeter of the brooder suggests they are uncomfortable and requires investigation. This distribution may be caused by a draft, external noises that are scaring them or uneven light distribution.

Warmth is critical to baby chicks, but their need for artificial heat diminishes as they age.

So how do you know if your brooder is the right temperature for your new chicks? In addition to noting your chicks’ positions in the brooder, a thermometer is a great tool. Brand new baby chicks prefer temperatures just under 100 degrees. However, their need for heat decreases about 5 degrees per week until they are about 10 weeks of age.

Approximate Heat Needs by Age
Week 190 – 95°
Week 285 – 90°
Week 380 – 85°
Week 475 – 80°
Week 5, 6, 770 – 75°
Week 865 – 70°
Week 965° minimum

Where to Place Lamps?

Suspend two heat lamps, each fitted with an incandescent 60-watt bulb, 12-18 inches above the floor of the brooder. Gooseneck lamps work, or infrared heat lamps can be purchased at your feed dealer. These can be fitted with special heat bulbs, but often an incandescent bulb will produce enough heat.

How Many Lamps?

Two lamps are important. If one burns out in the wee hours of the night, the other will keep the chicks warm until morning. Placing a sheet of cardboard over the brooder helps retain heat, but be very cautious about keeping anything flammable away from hot bulbs.

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