Your Poul­try

Why your chick­ens are full of hot air

NZ Lifestyle Block - - Contents - Words Sue Clarke

Breath­ing is a fun­da­men­tal process that al­lows mam­mals to oxy­genate their blood.

But the res­pi­ra­tory sys­tem of a bird is dif­fer­ent from that of peo­ple and other mam­mals. A bird has air sacs through­out its body (see page 72) which are ex­ten­sions of its lungs. They do not have a mus­cu­lar di­aphragm (like hu­mans) which acts like a bel­lows, draw­ing air in and out.

The far more com­plex res­pi­ra­tory sys­tem of the chicken en­sures it al­ways has fresh oxy­gen flow­ing through it.

The sys­tem is made up of: • nose • throat • tra­chea (wind­pipe) • lungs • air sacs • cer­tain bones

The lungs are small, fairly rigid and an unusual shape be­cause they are de­signed to fit around the ribs and spine. If you are ever per­form­ing a necropsy (cut­ting up and ex­am­ing a dead bird to check for signs of ill-health) or pro­cess­ing it for eat­ing, the lungs should be a bright pink-red-orange colour.

The air sacs are unique to birds and are thin-walled, look­ing like plas­tic wrap. There are four pairs around the body ex­tend­ing out from the lung tis­sue, and a sin­gle cer­vi­cal air sac which sits in the front of the neck. They cir­cu­late air from the lungs into other parts of the body, around the or­gans and into spe­cial pneu­matic bones.

The air sacs have a va­ri­ety of jobs: • they help to cool body tem­per­a­ture; • they pro­vide buoy­ancy to swim­ming birds;

• they fill with air to help the bird when it flies.

The av­er­age res­pi­ra­tion rate of adult poul­try is 30 breaths per minute (vs 12-18 for a hu­man). It means good ven­ti­la­tion of a coop is im­por­tant, to pro­vide fresh air and to get rid of mois­ture, but with­out mak­ing it un­com­fort­able or un­healthy for your chick­ens. For ex­am­ple, by shut­ting up a coop in win­ter to pre­vent heat loss, you can de­prive a flock of oxy­gen and in­crease the mois­ture in the air. The mois­ture con­denses and ei­ther drips off onto the birds be­low or makes the floor­ing ma­te­rial wet. This can quickly cre­ate a bad smell, and in­creases the risk of disease.

The best op­tions are to: • in­su­late the coop roof; • pro­vide an out­let for spent, warm air just be­low the eaves; • pro­vide an in­let at a lower level (which could be a hen-size door in a small coop). The vents al­low air to be drawn in from be­low, and once warm, to exit at height, tak­ing the mois­ture out with it.

The prob­lem with breath­ing

The chicken’s com­plex res­pi­ra­tory sys­tem means birds are more prone to res­pi­ra­to­ryre­lated dis­eases. The fac­tors that com­monly cause prob­lems are: • virus • bac­te­ria • fungi • par­a­sites • en­vi­ron­ment

It’s also com­mon for one prob­lem to lead to an­other. For ex­am­ple, a bird may catch a vi­ral disease, leav­ing it vul­ner­a­ble to bac­te­ria af­fect­ing a lung or air sac.

In the early years of the 20th cen­tury, res­pi­ra­tory dis­eases were known as PPLO – Pleuro Pneu­mo­nia-like Or­gan­isms – be­cause they tended to oc­cur to­gether, and there was no sci­ence at the time to help vets iden­tify the dif­fer­ent causes. That’s be­cause the symp­toms of most res­pi­ra­tory ail­ments are the same, although there may be sub­tle dif­fer­ences which can dif­fer­en­ti­ate them to an ex­pe­ri­enced eye. These in­clude: • laboured breath­ing • dis­charge from the eyes and nose • gasp­ing • cough­ing • sneez­ing

Since the mid-20th cen­tury, vac­cines have been de­vel­oped for use by poul­try

There are vac­cines but these are mostly un­avail­able to the small flock owner.

breed­ing com­pa­nies to pro­tect large com­mer­cial flocks. These are mainly used to pre­vent com­mon vi­ral dis­eases like in­fec­tious bron­chi­tis (IB) and in­fec­tious laryn­go­tra­cheitis (IL).

The same com­pa­nies have also de­vel­oped breed­ing flocks that are free of My­coplasma gal­lisep­ticum, a bac­terium that is a com­mon cause of many chronic res­pi­ra­tory dis­eases in poul­try. Their chicks will be free of it at hatch­ing, although they can con­tract it dur­ing rear­ing un­less they re­ceive a vac­ci­na­tion.

Vac­ci­na­tions are rarely an op­tion for the small flock owner due to their high price, spe­cial stor­age con­di­tions and ad­min­is­tra­tion pro­to­cols, and the strict quar­an­tine pro­ce­dures re­quired to make them ef­fec­tive.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.