10 THINGS YOU PROB­A­BLY DON’T KNOW ABOUT YOUR FLOCK

Why hu­mans don't taste like chicken, and how they see the world quite dif­fer­ently to us. Words

NZ Lifestyle Block - - Your Poultry - Sue Clarke & Nadene Hall

MANY HU­MANS think that the an­i­mals and birds un­der their care have the same sort of senses as hu­mans. They also give them the same sort of thought pro­cesses as hu­mans, as­sum­ing that they worry about their fu­ture, re­live the past, or mir­ror our own de­sires for com­fort and a warm meal on a cold win­ter's day.

Much of this can be at­trib­uted to an­thro­po­mor­phism, the at­tri­bu­tion of hu­man form or other char­ac­ter­is­tics to any­thing other than a hu­man be­ing. Many town dwellers don't have con­tact with an­i­mals and birds in a more nat­u­ral en­vi­ron­ment so they can have an over­sen­si­tised per­cep­tion of just what an an­i­mal or bird is ca­pa­ble of be­ing aware of.

It's in­ter­est­ing to look at what senses birds ac­tu­ally have, where their pri­or­i­ties lie and re­al­is­ing that they act more by in­stinct than any other height­ened brain process be­cause their brains are very small. Their senses work dif­fer­ently to those of hu­mans, mak­ing it amaz­ing how much we have in com­mon.

WE’RE VERY SIM­I­LAR

Hu­mans and chick­ens share more than half of their genes. The In­ter­na­tional Chicken Genome Se­quenc­ing Con­sor­tium found ap­prox­i­mately 60% of chicken and hu­man genes are nearly iden­ti­cal. But chicken genes are far more stream­lined than hu­mans; chick­ens have a to­tal of about 20,000-23,000 genes in 1 bil­lion DNA base pairs, com­pared with the hu­man count of 20,000-25,000 genes in 2.8 bil­lion DNA base pairs, mostly be­cause hu­mans have far more ‘junk' DNA.

It might be a lit­tle creepy to find out that while it isn't ac­ti­vated, chick­ens do have the genes re­quired for grow­ing teeth. Sci­en­tists tweaked those genes in de­vel­op­ing chick em­by­ros to stim­u­late teeth growth and found the em­bryos did de­velop teeth. No live chicks with teeth were al­lowed to hatch, and it's not known if they would have lived or not or if they would re­tain the teeth af­ter hatch­ing. It is known that par­rot em­bryos briefly de­velop ‘teeth' but these are ab­sorbed into the beak be­fore hatch­ing.

CHICK­ENS HAVE FAR BET­TER EYE­SIGHT THAN US (IN THE DAY­TIME)

The chicken eye is about 25 times as large as a hu­man eye as a per­cent­age of head size and their eye­sight is much more de­vel­oped.

STUD­IES HAVE

SHOWN that the cor­rect

level of vi­ta­mins and min­era

ls plays a part in help­ing

to lower stress, dis­ease

and as­sist max­i­mum pro­duc­tion

in chick­ens. Be­cause

raw in­gre­di­ents of­ten

lack suf­fi­cient lev­els

of vi­ta­mins and min­er­als, these

are added to a good

qual­ity com­mer­cial poul­try

feed, in­clud­ing the pro­tec­tive vi­ta­mins, A and

E.

We have tri-chro­matic eye­sight (we see red, green and blue) while chick­ens have te­tra-chro­matic vi­sion so they see four wave­lengths (red, green, blue, and ul­tra­vi­o­let).

It means chick­ens see things very dif­fer­ently to us, with many colours ap­pear­ing to glow, for ex­am­ple the feath­ers of other birds which iden­tify them as male or fe­male glow if you're another bird but ap­pear the same colour to hu­mans. It means chick­ens can also judge di­rec­tion us­ing changes in the

colour of UV light to guide them.

How­ever, due to evo­lu­tion­ary dif­fer­ences chick­ens don’t have the rods in their eyes which give us rel­a­tively good night vi­sion. They can’t see much at all at night, which is why they roost out of the way of preda­tors once night be­gins to fall.

CHICK­ENS TILT THEIR HEADS TO GET A BET­TER VIEW

The chicken eye has a form of built-in bifocal, so they can see par­tic­u­larly well over a dis­tance, and things that are right up close. The mech­a­nism (called a fovea) that al­lows them to see far away sits the right way up in the eye, but the one for closeup vi­sion sits side­ways, which is why a chicken tilts its head if you get close-up to it, as it ad­justs its vi­sion.

BLIND CHICK­ENS RE­SPOND TO LIGHT

A hen’s lay­ing cy­cle is de­pen­dent on light. Once day­light goes above 16 hours, the hor­mones that gov­ern lay­ing are stim­u­lated and egg pro­duc­tion be­gins. The same hor­mone lev­els be­gin to drop as day­light hours shorten in late sum­mer, which is when birds stop lay­ing and go into a moult.

These hor­mones are con­trolled by the pineal gland in the fore­head and are stim­u­lated by bright light which is why a blind hen can ‘see’ light and will still lay eggs (as­sum­ing she is kept safe and has ac­cess to food and wa­ter).

CHICK­ENS USE THEIR FEET AND SKIN TO HEAR

Chick­ens per­ceive sound from 15 to 10,000Hz, com­pared to hu­mans who can hear sounds up to 20,000Hz. But they also have sen­sory or­gans in their feet, and to a lesser ex­tent in their skin, so they also feel vi­bra­tions in the ground, use­ful if there’s a sneaky prowl­ing preda­tor in the dark.

Hear­ing is an im­por­tant sense. In test con­di­tions sci­en­tists have found chicks can find their moth­ers, even if her hid­ing place is dis­guised, by lis­ten­ing for her call.

Hens be­gin ‘talk­ing’ to their chicks be­fore they hatch, and if you lis­ten care­fully in the days be­fore hatch­ing, you’ll hear the chicks peep­ing back at her.

DEAF CHICK­ENS CAN RE­PAIR THEIR HEAR­ING

There’s no such thing as a deaf chicken, and that dis­cov­ery was ac­ci­den­tal. Sci­en­tists study­ing how drugs can cause hear­ing dam­age were ad­min­is­ter­ing a drug known to cause hear­ing loss to chick­ens as part of an experiment to help hu­man hear­ing loss. Af­ter a cou­ple of weeks, as they pre­dicted, the chick­ens had lost most of the tiny in­ner ear hair cells that al­low chick­ens (and all mam­mals) to hear. But three weeks later, the sci­en­tists found the chick­ens in the study had re­placed their hair cells, restor­ing their hear­ing.

More re­search showed all ver­te­brate crea­tures, ex­cept hu­mans, have this abil­ity, and the find­ing is now the ba­sis of re­search which sci­en­tists hope will cure hear­ing loss and tin­ni­tus in peo­ple.

A SMELLY COOP IS OF­FEN­SIVE TO YOUR FLOCK

Chick­ens have a good sense of smell, although that’s only re­cently been proven. In­ter­est­ingly, the kiwi (which has its nos­trils at the tip of the beak) have the best sense of smell of all birds and it’s their pri­mary sense as they feed at night, sniff­ing out worms and in­sects.

Chick­ens can’t smell quite as well as we

can, but new re­search shows they have a sim­i­lar num­ber of ol­fac­tory re­cep­tors to hu­mans.

They use their nos­trils to search for food and to recog­nise other birds. They also have the abil­ity to smell high con­cen­tra­tions of car­bon diox­ide and am­mo­nia, and have spe­cial nerves which make these smells painful so a filthy coop is an un­com­fort­able place for them to be.

Re­searchers have found chicks are able to smell even while still in the egg. They rubbed a straw­berry scent over de­vel­op­ing eggs, then found the re­sult­ing chicks pre­ferred straw­berry-scented shav­ings and wa­ter.

They also re­spond in an alert man­ner if they smell the ma­nure of preda­tor an­i­mals, even if they've never had con­tact with that an­i­mal.

THE CHICKEN BEAK IS LIKE A HAND

The beak is a sen­sory or­gan through which birds can dis­tin­guish hard, soft, hot, cold and struc­tural dif­fer­ences such as rough or smooth.

The beak also feels pain which is why the com­mer­cial prac­tice of trim­ming the sharp hook at the tip to pre­vent feather peck­ing and can­ni­bal­ism is done in the very first days of life be­fore the nerve end­ings have grown to the tip. This is done in the hatch­ery when a chick is one day old with a laser light which only touches the very tip of a chick's beak caus­ing it to dry and drop off by the time the chick is a week old so there's no pain for the bird.

WE WOULDN’T TASTE LIKE CHICKEN TO A CHICKEN

Chick­ens do have taste buds, but only 350 com­pared with a hu­man's 9000 so mak­ing their food ‘tasty' does not have the same im­por­tance to them as it does to us, although they can dis­tin­guish be­tween sweet, salty, bit­ter and sour. By the time a chicken tastes some­thing it has eaten, the food is al­ready past the point where it could spit it out.

Com­mer­cial foods can vary in looks and tex­tures and it is these which ap­peal or not to a chicken, rather than taste. Some grains will glow (re­flect­ing UV light) and are very ap­peal­ing to birds which will peck out these bits first be­cause they glow, not be­cause they are more tasty.

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