Ventriculus (Gizzard)
The ventriculus, or gizzard, is a part of the digestive tract of birds, reptiles, earthworms, and fish. Often referred to as the mechanical stomach, the gizzard is made up of two sets of strong muscles that act as the bird's teeth and has a thick lining that protects those muscles (see Figure 5). Consumed feed and the digestive juices from the salivary glands and proventriculus pass into the gizzard for grinding, mixing, and mashing.
Fig. 5. Inside of a chicken gizzard, with the internal lining removed. Source: Jacquie Jacob, University of Kentucky
When allowed to free-range, chickens typically eat small stones. The acidic environment in the proventriculus softens the stones, and then the strong muscles of the gizzard grind them into tiny pieces. The stones remain in the gizzard until they are ground into pieces small enough to pass to the rest of the digestive tract.
Grit, a commercial product made up of small stones, can be used as a supplement to chicken feed. Chickens fed only commercially prepared feed do not need grit. Chickens that eat whole grains or chickens kept on pasture that do not consume enough pebbles with the forage typically require a supplementation of grit. Grit should not be confused with limestone or oystershell, which are given to laying hens as sources of calcium for their eggs' shells.
When a chicken eats a small, sharp object, such as a tack or staple, the object is likely to get stuck in the gizzard. Because of the strong grinding motion of the gizzard's muscles, such sharp objects can put holes in the gizzard wall. Chickens with damaged gizzards grow thin and eventually die. Preventing this situation is a good reason to keep a poultry house free of nails, glass shards, bits of wire, and so on.
The ventriculus, or gizzard, is a part of the digestive tract of birds, reptiles, earthworms, and fish. Often referred to as the mechanical stomach, the gizzard is made up of two sets of strong muscles that act as the bird's teeth and has a thick lining that protects those muscles (see Figure 5). Consumed feed and the digestive juices from the salivary glands and proventriculus pass into the gizzard for grinding, mixing, and mashing.
Fig. 5. Inside of a chicken gizzard, with the internal lining removed. Source: Jacquie Jacob, University of Kentucky
When allowed to free-range, chickens typically eat small stones. The acidic environment in the proventriculus softens the stones, and then the strong muscles of the gizzard grind them into tiny pieces. The stones remain in the gizzard until they are ground into pieces small enough to pass to the rest of the digestive tract.
Grit, a commercial product made up of small stones, can be used as a supplement to chicken feed. Chickens fed only commercially prepared feed do not need grit. Chickens that eat whole grains or chickens kept on pasture that do not consume enough pebbles with the forage typically require a supplementation of grit. Grit should not be confused with limestone or oystershell, which are given to laying hens as sources of calcium for their eggs' shells.
When a chicken eats a small, sharp object, such as a tack or staple, the object is likely to get stuck in the gizzard. Because of the strong grinding motion of the gizzard's muscles, such sharp objects can put holes in the gizzard wall. Chickens with damaged gizzards grow thin and eventually die. Preventing this situation is a good reason to keep a poultry house free of nails, glass shards, bits of wire, and so on.
