Welsh Poultry Centre

Moulting Explained

The vast majority of laying hens in the UK are kept for one season, before being culled.  The reason is largely economic: producers evaluate feed costs against egg production and do not want to spend money on feeding unproductive birds. As a result, hens have been bred to lay higher numbers of eggs and high production levels in the first year.

Yet, just because this is the ‘norm' now does not mean it will always be so. Indeed, many organic egg producers are keeping birds into their second lay. The justifications include high costs of replacement pullets, a growing interest in more robust breeds and strains,  and a desire to look at maximising productivity in a different and more long term way. 

Keeping birds for two or more laying seasons means that birds must be taken through a naturally occurring annual moult and it is important to understand this process to ensure birds come out the other side in good health, prepared for another busy period of production.

Why chickens moult

Chickens moult for a number of reasons but the annual moult usually occurs in the autumn and is triggered by a decrease in daylight length (less feeding time thus reduced feed intake), combined with the end of an intense laying period. During the summer months the birds will lose the smaller feathers closer to their body. This is an attempt to cool down. The larger feathers will usually have been developed in the previous moult and after a summer's use they begin to look rough and lose some of their colour. The shorter day length is a natural trigger to renew all their feather in preparation of colder times to come. In this way the moult is a way of conserving energy over the winter period that would otherwise be spent keeping warm.

The renewal of feathersrequires protein. It is not possible for the bird to assimilate enough proteinto maintain egg production as well as renew feathers. With the onset of winter there would naturally be less food available to support chicks, so it is therefore a good time to close down egg production, renew feathers and build upbody reserves for the following spring.

Although the birds will naturally moult in the autumn, other factors may trigger a moult. Disease, parasites, mismanagement, lack of food or water, extreme heat or cold, changes to a lighting regime and even predator attacks can all induce moult at any point of time. Such induced moults may or may not also include a reduction in egg production. They are often called a partial moult.

Birds that have been laying heavily for 11 months will moult easily in the autumn since this is the natural moulting time. If they have had artificial lighting and finish their intensive laying period in the spring, they do not moult as easily and may carry on egg production until the following autumn.

The moulting process

Even before a pullet starts laying it has gone through one complete and four partial moults. The first is between 1-6 weeks, when the chick sheds its downy first coat. Between 7-9 weeks, and again at 12-16 weeks, the bird goes through a partial moult, replacing some feathers. The final partial moult occurs around 21 weeks when the tail feathers start to grow. In the annual moult feathers are lost in the following, specific order: head, neck, body, wing, (primary feathers, on the outside of the wing, will be lost sequentially from nearest axial feather tothe tip of the wing, followed by a sequential loss of the secondary feathers,to the body of the bird) and finally tail.

The new feathers are called pin feathers and grow out of the skin wrapped in a sheath, called a keratin sheath. The bird will, in the act of preening, pull off the sheath to allow the feather to open. They are sometimes referred to as blood feather as they have large, central blood vessel and can bleed profusely if torn or damaged.

Early and Late Moulters

An early moulter is a bird that moults slowly over a long period. Early moulters can take up to six months to moult. They tend to replace feathers as they lose them. Although they follow the same specific pattern of feather loss, it takes longer. Early moulters tend to be less prolific layers than late moulters and can be identified by their well-groomed appearance.

The late moulters will look increasingly ragged as the lay progresses and will then replace them all in a short period of time. Late moulters tend to be higher egg producers such as the hybrid strains. The primary wing feathers determine whether a bird is an early or late moulter. Although the moulting process in a good laying bird will take around 90 days it is only when the large, stiff primary feathers start moulting that egg production ceases. The early moulter will lose these feathers individually whereas the late moulter will lose these feather two or three at a time. The new feathers will start appearing shortly after the old ones have been shed. A late moulter can be identified by groups of replacement primary feathers showing similar stages of growth, whereas an early moulter will only have one at a time.

Minimising the moulting period

Moulting is a difficult time for the birds. It involves hormonal changes and high energy and protein requirement. It also occurs at the end of a long laying period that has seen their body weight slowly decline.

Maximising productivity from individual birds and keeping them for two or more seasons has advantages, and it is quite reasonablefor producer who want to keep birds over several seasons to balance feed costs against production over a birds life, rather than at any point in their life. In order to maintain good bird health and productivity it is important to ensure that birds are receiving a good, high quality diet during their moult; many suggest that additional protein or a higher protein ration should be fed. Not only do they have to replace feathers, but they also have to increase their body weight by laying down fat. This is best done with a high quality diet and as little stress as possible during this period.

To moult or not tomoult

Economic reality might initially suggest that it is not worth keeping birds into their second lay. Even if early moulters are identified and culled, the birds would produce on average 15% less eggs per bird in the second year than in the first. This is not only because the rate of lay is lower in the second year, but because they also tend to start their second annual moult earlier. Although moulted birds do eat less feed in their second year, the overall feed cost per dozen eggs is slightly higher because they lay less. They also obviously require feeding during the unproductive moulting period.

But there are real advantages. For example, there is no doubt that birds in their second year are less prone to disease and, oddly, predator attack - presumably because the ‘easy prey' were had in their first year and the birds become wiser with age. There is also a significant saving in terms of the additional time and labour required when preparing and establishing a new flock. So while there is indeed a slight decline in profitability during the second year, this should be weighted against the potential time/labour savings. And while you will have less eggs, if the early moulters are culled you will have more reliable egg production from a hardier bird.

Ends article

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About the author

Stephen Merritt is a partner in The Welsh Poultry Centre and an accredited advisor and board member of The Institute of Organic Training and Advice and has spent over 30 years working in sustainable agriculture in developing countries, England and Wales.  In the last 10 years Steve has specialised in free range and organic poultry production and now offers on farm advice and training to this sector.