Dif­fer­ences in lay­ing

Country Smallholding - - Poultry -

QWhy do some hens lay re­ally well all the time and oth­ers keep tak­ing time off? If they are kept in the same con­di­tions and fed the same, should they not be more uni­form?

VR SAYS: Hens are not ma­chines and, al­though the hy­brids have been se­lected for uni­for­mity, there are still in­di­vid­u­als who buck the trend. Sim­ply, bird breed­ing hor­mones are ac­ti­vated by in­creas­ing light lev­els, so peak time of egg pro­duc­tion is in the spring with length­en­ing days. That is why it is pos­si­ble to keep hens lay­ing in the win­ter by in­creas­ing their light lev­els to 14 hours a day. Spring length­en­ing days is well or­gan­ised by Mother Na­ture as the baby birds or chicks then have high-pro­tein in­sects to eat from the warmer days to max­imise growth and sur­vival rates. The num­ber of chicken eggs in a clutch is the num­ber of eggs laid on con­sec­u­tive days. Each egg takes 25 hours from ovu­la­tion to lay­ing, so lay­ing is later each day. Ovu­la­tion of the next yolk oc­curs 30 min­utes af­ter lay­ing, so a day is missed if ovu­la­tion oc­curs in the dark. The hy­brid hens have been se­lected for a shorter ovu­la­tion time so clutch size is greater, i.e. there are fewer missed days. This in­tense pro­duc­tion rate cer­tainly short­ens the life of hy­brids. Qual­ity of shell is in­her­ited but also de­pends on qual­ity of feed and lack of dis­ease – in­fec­tious bron­chi­tis pro­duces wrinkly and weak shells, for in­stance, and stress (such as be­ing chased, fright­ened or caught roughly) can pro­duce dis­torted shells. At the be­gin­ning or end of a lay­ing pe­riod aber­rant eggs can be pro­duced such as very small, very large or ones with no yolk. Pig­ment such as that Wel­sum­mer and Marans put on the shells gets lighter with the length of lay, so, if show­ing eggs, the early ones are more likely to have the darker and denser colour. (The ex­cep­tion to this is the blue egg laid by the Arau­cana and its crosses as the colour is laid down through­out the shell.) Dou­ble-yolked eggs are more likely to ap­pear in the sec­ond year plus of lay and are caused by two ova (yolks) de­scend­ing into the oviduct at the same time, the white and shell be­ing added as nor­mal but around a larger mass. As pure breeds get older, the shell qual­ity of their eggs usu­ally suf­fers and they lay fewer eggs each year. If you just want a few for in­cu­ba­tion from a good line, then this is fine, but for eco­nomic pro­duc­tion, flocks are changed on a reg­u­lar ba­sis. The stock cube and soup trade could not ex­ist with­out spent hens. Ducks take 24 hours to pro­duce an egg so they can be kept in their hut un­til about 9am when lay­ing has taken place and you then can en­joy the eggs in­stead of the mag­pies or crows steal­ing them.

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