Breeding chickens is of course a fairly straight forward process, you put a good cockerel in with some hens and providing both are fit and healthy and your cockerel is fertile, he will mate with the hens regularly and before you know it, you have fertile eggs.
There are a few other things to consider though if you are hoping to create a strain of birds for utility, show or if you simply want to keep to or improve the standard of the breed you have chosen.
Getting good results can take years and to get the best results, you need to hatch as many chicks as you can, raise them and have an eye for the best birds that will improve your line and next years offspring. Breeding top birds doesn't happen overnight but hopefully if you are new to breeding chickens, this article will give you some ideas of where to start.
Start with the best stock you can get your hands on. This may seem like an expensive approach, considering some birds from top breeders will sell for hundreds of pounds, however if you consider the number of years of selective breeding it takes to create such birds, a few hundred pounds can be very cheap to obtain such a bloodline and short cut years of breeding and selection.
Once type is established, it is common for inbreeding to be practised within the flock. There are many hatching eggs being advertised on sites such as ebay that boast eggs from unrelated cockerels and this is great for introducing vigor into a bloodline but introducing a new mixture of genes doesn't guarantee your chicks will grow up to look similar to their parents! By using an unrelated cockerel for breeding, even if he looks perfect, you could find chicks resemble their grand parents or great grandparents. This is especially true for breeds with mixed ancestors and these days, it's very hard to find real ‘pure breeds'. Who is to say there hasn't been a cross with another breed a few generations ago?
By inbreeding within the flock, you are breeding from related stock, keeping the same genetic pool and therefore as faults arise, these can be eliminated through selection. As the gene pool narrows down, providing just the desired characteristics, you will produce similar birds 'like peas in a pod'. If birds become too closely related then vigour and hatchability will suffer. The degree of inbreeding (how close the relatives are) will determine how soon you will see this problem. There are mathematical formulas for the coefficient of inbreeding present but it is difficult to say how far you can go. Generally speaking, it is possible to mate brother to sister for 5 or 6 generations before seeing problems but with close breeding like this, you are 'fixing' characteristics within the offspring faster than when flock breeding with a larger gene pool. This can be desirable at times but remember you are fixing both good and bad qualities so sometimes you can be fixing inherent weaknesses within a breed such as longevity or laying ability.
Breeding with a large breeding pen is a better solution which allows close breeding to be performed as required to fix traits but birds with weaknesses can be removed and birds that have then been closely bred can be reintroduced to more distant family members from the flock in the breeding program to improve vigour of their offspring.
After a number of years of breeding and selecting the characteristics you desire, your strain will start to take shape and if you've been careful with your selection you should be getting pretty close to what you set out to achieve.
If after a number of years of inbreeding, you find the characteristic you are looking for isn't in your strain then it may be necessary to outcross to a bird that has this characteristic in order to bring it in. The best choice is to bring in another pair of birds from the breeder you originally obtained your birds from, assuming the characteristic is present in this pair of course. This bird should almost be a known quantity in that it has most of your lines characteristics already and you know what sort of faults are likely to crop up already.
Another reason to bring in fresh blood is when your strain of birds has become so inbred that hatchability is suffering. This can usually be overcome though if you keep sufficient numbers of birds.
When outcrossing, it is advisable to hatch offspring from the imported birds and select from them the birds with the desired quality. This is narrowing down the gene pool further for this characteristic but is also giving you an idea of the undesirable characteristics you will be introducing.
It is almost impossible to find perfect birds so when selecting birds for the mating pen, if you include one with an undesirable characteristic, mate this to a bird that is very good with this characteristic.
The comb of a cockerel comes from the dam. If you would like to improve the comb of a cockerel, select hens with a good comb in the breeding pen. An example of this can be seen below. The Light Sussex cockerel on the left was bought for £30 from a well known breeder. He has some very good points but a poor comb. If he had a good comb, he would have been worth £30 more to the seller. The Standard requires a single comb of medium size, evenly serrated and erect, fitting close to the head. He was used in the breeding pen with two hens from the same breeder and selection was performed in the first year for the hens with the best overall qualities and above all the best, evenly serated combs. In year 2, he was mated to his 7 daughters and a number of young cockerels, all with improved combs were hatched (one of these is shown in the picture on the right).
There are few books that are written in a non technical manner concerning genetics, it is after all a complicated subject. If you are interested in breeding show quality birds then Dr Clive Carefoot's Creative Poultry Breeding and Grant Brereton's 21st Century Poultry Breeding is vital reading and reference material. I would highly recommend you read both. It's hard to find Creative Poultry Breeding these days but Veronica Mayhew did have a number of reprints a few years ago. Grant Brereton's book is available from Amazon.