Anatomy of Broiler Birds

The anatomy of broiler birds is complex. Birds have many anatomical features that are different from mammals. For example, birds posses a special gland above the eye, which has ducts to drain to the nose and birds do not have a bladder. Broiler birds such as chickens and turkeys possess avian anatomical features. Their muscles are gray-white and tender for eating and the hen's reproductive system produces eggs that humans can eat.

  1. External Anatomy

    • Broiler birds such as chickens are covered with feathers over the majority of their skin. These feathers are arranged in feather tracts. The skin of a turkey or chicken is thin and semi-transparent; veins, muscles and fat can be seen underneath the skin in these birds. Skin on the birds' face and feet is thickened and can be white or yellow. Combs and wattles are likely to be bright red in commercial laying hens while breeder hens can have reddish yellow skin in these areas.

    Internal Anatomy

    • Muscles are the first organs that come to view when examining a broiler bird's internal anatomy. Breast muscles are gray-white and leg muscles are a darker gray-white color. The heart is a triangular-shaped organ toward the head of the bird. It is gray-white in color with a band of yellow fat at the base and a clear sac surrounding it. A chicken heart has four chambers and the blood volume of an adult bird accounts for approximately 6 percent of its body weight. Blood cells of birds are very different from those of mammals, yet little is known of these cells. The heart is surrounded by the lobes of the bird's liver, which is the largest internal organ. Attached to the liver is a sac-like organ called the avian gallbladder. The lungs are adhered closely to the ribs and avian lungs are pink-red or orange-red in color.

    Digestive System

    • On the bird's right side is the gizzard and the stomach. The spleen can be seen in between these two organs and is approximately an inch long on adult birds. The stomach is gray and the gizzard is dark brown. The small intestines are made up of a duodenum surrounding the pancreas, the jejunum and the ilium. Two sac-like structures called cecae are attached. The large intestine is called the cloaca.

    Reproductive System

    • Chickens develop in the left ovary and oviduct before they reach maturity. While the ovary has thousands of oocytes, just a few of them mature into follicles and are then ovulated. The ovum is passed down the oviduct where the egg is formed and then laid. The ovum becomes the egg yolk. Eggs are generally laid in the morning, and one egg is laid each day. Male broiler birds have a simple reproductive system without seminal vesicles or prostates and a small phallus.