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Have you ever stopped to ask why do chickens lay so many eggs? Some of the common breeds kept as pets may lay as many as 300 in a season. And the laying season is very long - stretching out over most of the year. Certainly, in nature, no other bird does this.
For most birds there is a “breeding season” which starts as the length of the day increases towards the middle or end of winter. In anticipation of this, birds form (or re-kindle) breeding pairs and make a nest of some sort. Once done the female lays a “clutch” of eggs - the collection of eggs in the nest. Clutch size varies with species (kiwi = 1, Ostrich can be up to 50!). In the case of the Jungle Fowl, clutch size is 4-6.
Why mention Jungle Fowl?... well they’re the original chicken. Over centuries – but particularly the 20th century, selective breeding by humans has taken the Jungle Fowl and produced lots of breeds. Brown shaver, Leghorn and Silky Bantam are just a few of the more than 1000 different breeds.
Some breeds were produced for looks, others to meet certain functions. The terms “meat breed” and “egg breed” relates to those that were bred with these specific farming objectives. Almost all our store-bought eggs are produced by farms stocked with Brown Shavers.
So, back to our original question…. Why do chickens lay so many eggs? Well, if they’re a Brown Shaver, it’s because their breeding has resulted in an abnormally long breeding season and the loss of a “clutch size” definition (Brown Shavers will lay a new egg on top of a stack of 20 others!).
This is great as a source of food for us…. But not so great for the chickens.
Laying an egg almost every day is pretty draining. Without a steady diet of pellets designed specifically for laying birds, they couldn’t keep up with this demand and their health would suffer quickly. While a free-range lifestyle seems idyllic for these birds, they rarely can find enough balanced food to meet their needs without pellets being available too.
There is also a physical toll on their body and reproductive organs from this heavy workload. Malfunctions are common and can result in “Yolk Peritonitis” or egg duct ruptures. These are one of the most common causes of death in Brown Shavers kept as pets. As a result, life expectancy for this breed may be as little as 2-4 years (compared with 10-12 for some other breeds).
Treatment for affected birds is available. This often involves surgery to remove egg remnants from their abdomen and treat the peritonitis. Ideally the egg duct is also removed to stop the laying process permanently. These birds can then go on to live a more normal life expectancy. While it might not be for every owner, we’ve had the opportunity to help a number of dedicated families and save the lives of their much loved chooks this way.
Can these issues be avoided? When choosing the right breed to keep as pets, it’s worth thinking about what you’re looking for. Breeds that produce less eggs per year may live longer and have less health problems.
Kevin Turner BVSc
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