Cows are recognized by their udders and teats, an image associated with milk production. While typically having four teats, variations can occur, raising questions about implications for the cow and dairy farming.
The Standard Teat Count
A cow’s udder is composed of four mammary glands, each with a single teat. These four teats are arranged in two pairs, with each teat connected to its own separate mammary quarter. This anatomical setup allows for efficient milk production and distribution, whether for nursing calves or for machine milking.
This four-teat configuration is optimal for milking efficiency and udder health. Each quarter functions independently, meaning milk from one quarter does not mix with milk from another. This design provides sufficient capacity to feed a calf, even if multiple births occur, and supports the high milk yields expected from modern dairy cows.
When Cows Have More Teats
Some cows are born with more than the standard four teats, a condition known as supernumerary teats or hyperthelia. These extra teats are a common anatomical variation in cattle, with studies indicating that up to 50% of dairy calves may be born with them. Prevalence varies, with some reports showing incidences up to 40%.
Supernumerary teats form along the “milk line” during early embryonic development, where primary teats also develop. They are located behind the rear teats, between front and rear teats, or fused to a normal teat. This trait is considered polygenic, meaning it results from the influence of multiple genes, making its inheritance complex and not easily predicted or “bred out” by targeting a single gene.
Practical Implications of Extra Teats
The presence of supernumerary teats can have various practical implications for a cow and its management. Many extra teats are “blind,” meaning they do not connect to mammary tissue or have a streak canal, and therefore cannot produce milk. However, some supernumerary teats can be functional, producing small amounts of milk, a condition referred to as hypermastia.
Even non-functional extra teats can pose challenges. They may interfere with a calf’s ability to latch onto a functional teat or cause confusion during nursing, potentially leading to inadequate colostrum intake. For dairy operations, extra teats can hinder the proper attachment and function of milking machines, including automated systems, making the milking process less efficient. Furthermore, supernumerary teats, especially those that produce milk but are not regularly milked out, can become reservoirs for bacteria and increase the cow’s susceptibility to mastitis, an udder infection.
Because of these potential issues, extra teats are removed, particularly in young dairy calves, typically between two to six weeks of age. This removal, called teat clipping, is a simple procedure in young animals due to less blood circulation. For older animals, or if the teat is larger, a veterinarian may perform the removal using local anesthetic and surgical techniques. While some extra teats may be left alone if they cause no problems, removal is a common practice to prevent future health issues and improve milking efficiency.