The humble commercial hybrid hen has been bred to ensure peak egg production and consistency of yield – but exactly how many eggs a day does a hen lay a day, and how does the process happen?
Compared to her fancy breed cousins and broilers bred entirely for meat production, the commercial layer carries little spare flesh and concentrates all her energy into producing an egg every day. In the past, all these ex-caged hens would be sent to slaughter at 18 months of age before changes in shell quality and decreased frequency of laying became apparent.
We are now living in more enlightened times and hens are routinely rehomed into pet backyard homes to enjoy a well-deserved retirement (although only a fraction of the UK laying flock of some 40 million hens manages to achieve this happy outcome). Hens are now the fourth most popular pet in the country, which means there are lots of households out there getting lovely fresh eggs daily from their newly adopted hens!
We thought you might be interested to know the process which leads to a hen laying an egg for your breakfast.
Our hope for these hens is that anyone who rehomes them does so purely for the enjoyment of having pet chickens; however, the eggs are an added bonus, if your hen hasn’t gone into full retirement just yet. Therefore, you might also want to know how many eggs a day does a hen lay!
The laying process
Hens have only one functional ovary – the left one. The ovary contains follicles of differing sizes and maturity. When each follicle matures, it is called a yolk or vitellus. The yolk travels from the ovary into the oviduct. (See diagram).
The first part of the oviduct is the infundibulum, this is where the egg stays for roughly 15 minutes. If the hen has been mated this is where fertilization takes place. Beware! If you plan to breed from your girls it is important to know that sperm can survive in the oviduct for as long as four weeks.
The next part of the oviduct is the magnum where the egg remains for roughly three hours. The white is generated here. Passing down the oviduct the egg reaches the isthmus and remains for one hour while two membranes form around it.
Next comes a 24-hour period inside the uterus – the shell is formed at this stage. The final stage is the cloaca. With the help of the hormone arginine vasotocin, which induces uterine contractions, the egg is laid.
How many eggs a day does a hen lay?
You’d like to think this is an easy question – surely every hen pops out one egg a day? In theory, yes, but there are lots of factors which can affect egg production. So, just how many eggs a day does a hen lay?
A hen in her prime laying period between 20 weeks of age (point of lay) and 78 weeks of age would be expected to produce around 300 eggs annually. Within that time, she will also have periods of rest in her cycle when laying briefly stops. Happily, the majority of hens continue to lay after 78 weeks.
The humble hen egg is designed to be an ideal incubator and nursery for a growing chick embryo. The shell is porous – typically around 7,000 pores in the calcium carbonate shell allow air into the embryo. For this reason, it is not recommended that eggs are washed if floor-laid as bacteria can be introduced via this route. There are strict regulations governing egg production within the egg industry and eggs are not allowed to be sold as first quality if dirty or damaged in any way. Hens need 4g of calcium to produce one egg and if they are calcium deficient, this can affect their laying.
The hens we rehome have reached 18 months old, at which point their egg laying can slow down, especially if they go through a moult.
However, with a good diet, lots of regular sun and dust bathing, plus a bit of TLC, hens could lay up to three or four eggs per week.
What can affect a hen’s egg production?
As mentioned, a calcium deficiency is a major factor in a reduction of eggs. Then comes age, and the moulting process.
If your hen is sick or has been through any kind of trauma, this will also likely affect her egg laying for a short while. Rehomers often find that it takes a few days or even weeks after getting their hens home before they begin to lay – after all, it’s quite a process they go through.
Access to light is also a factor, and people often find their hens lay less during winter when daylight is shorter.
Finally, hens need a good quality, balanced diet in order to get the necessary nutrients for egg laying.
For more information about egg production: