An eclectic alphabet of chicken facts with a difference. Compiler: Andy Cawthray
‘R’ is for reproduction
A method of being able to tell the difference between male and female chicks based on the growth rate of their primary wing feathers. The wing feathers of the male birds grow slower than the females, though this is only evident when the chicks are between one and three days old, after which the feathers of the male birds will catch up in size. It is only really possible to reliably do this on hybrid chicks, where a fast feathering cockerel, such as a Leghorn, is crossed with a slow-feathering hen, such as a Rhode Island Red. Also, not all breeds or crossings will produce opportunities to feather sex successfully - a point worth noting if you buy young birds where the seller claims they know the gender of the chick as they have feather sexed the brood.
Also known as cloacal sexing, this is a traditional method of sexing day-old chicks, pioneered by the Japanese. This requires the study of the chick’s genital configuration within the vent. In order to make the genitals visible, the handler needs to squeeze the chick to invert the vent area. They will then be presented with 10 key variations in the presentation of the male and female organs, none of which will categorically define the sex of the bird without additional observations and a significant amount of experience. Commercial chicken sexers need 95% accuracy on 10,000 chicks to qualify in the role another point worth noting if you buy young birds where the seller claims they know the gender of the chick as they have vent sexed the brood.
This is a term that is more to do with genetics than anything else. However, it is used to describe the crossing of breeds that enable the keeper to be able to ascertain the sex of the offspring by their physical appearance, such as down colour or rate of feather growth (see earlier). This ‘linkage’ is more accurate than vent sexing at determining the sex of the offspring, and is frequently used within commercial hatcheries. It is often referred to as ‘sex-linked’, though this transmission of sex-linked characteristics is not always visible within the hatchlings, as the propensity towards behaviours like broodiness are also determined as ‘sex-linked’ but will not become evident until much later in the life of the offspring. When buying sex-linked chicks be sure to ask what the characteristic is, and, if in doubt, ask for evidence.
This is in a sense a form of sex-linkage which more specifically relates to the ability to determine the sex of the chick due to its appearance at hatch within a single pure
breed (which excludes it from sex-linked cross breeds). Original autosexing breeds include barred varieties such as barred Plymouth Rock, as well certain plumage types of breeds like Leghorn and Penedescena.
The autosexing characteristics of the barred Plymouth Rock (BPR) have been exploited by crossing with other pure breeds to produce new true breeding varieties such as Cobar (BPR cross with Cochin), Legbar (BPR cross Leghorn), and Welbar (BPR cross Welsummer). Despite this autosexing ability, a number of these breeds are now listed as rare and infrequently seen.
It is not yet possible to determine the sex of the chick that will be hatched by looking at the egg, or subjecting it to some form of non-invasive test. If it were, then commercial hatcheries would have no need to breed sex-linked birds, nor destroy the male chicks of laying strains that are hatched. Current available technology in terms of egg sexing is still only as good as the toss of a coin.
A ‘line’ is also known as a ‘strain’. It is a related population of chickens. Line breeding is when a superior quality cock or hen is used for breeding with its best opposite sex offspring in an attempt to concentrate the best qualities of the original parent and its best offspring. This process is repeated with each generation’s best offspring being mated back to the preferred parent.
Some lines will fail, as this type of breeding can concentrate not only the desirable qualities but also the undesirable within a short period of time. To be successful a good line breeding plan is required, along with maintenance of a number of lines or strains so additional ‘lines’ can be created with a view to removing the undesirable traits.
This should not be confused with line breeding, though it may be maintained via line breeding. A flock of this nature has no contact with other chickens, and remains genetically isolated from the rest of the chicken population. Reproduction remains in-flock, and no chickens are introduced from outside sources. It requires skill on behalf of the keeper to ensure that only the strongest and fittest birds are used for breeding, and only eggs from those matings are incubated to provide the next generation. The primary objective is to prevent the introduction of disease, or inheritable genetic abnormalities, from outside sources
MORE on reproduction next month.
Vent sexing is the only option with these Araucanas
Egg sexing is still a guessing game
Feather sexing is only possible in the first few days
Line breeding Minorcas
Offspring from a closed flock
A day-old Barred Plymouth Rock
Down colour is used for auto sexing