A-Z

An eclec­tic al­pha­bet of chicken facts with a dif­fer­ence. Com­piler: Andy Cawthray

Your Chickens - - Contents -

‘R’ is for re­pro­duc­tion

FEATHER SEXING

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.

VENT SEXING

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.

SEX-LINK­AGE

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.

AUTOSEXING

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.

EGG SEXING

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.

LINE BREED­ING

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.

CLOSED FLOCK

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

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.