Diary of a poultry farmer: Unravelling the puzzle of chicken with five toes

Saturday January 13 2018

Samuel Macharia feeds his chicken at Turi Farmers in Elburgon.

Samuel Macharia feeds his chicken at Turi Farmers in Elburgon. Scientists have proved that polydactylism in chicken can be suppressed or shifted to different phenotypes by exposing the developing embryos to low temperatures and injecting them with colchicine and insulin. PHOTO | JOHN NJOROGE | NATION MEDIA GROUP 

By SUBIRI OBWOGO
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As you are now aware, recently I added to my flock a couple of chickens with ‘weird’ features. One of them had five toes. 

Now, when I mention to people that a normal chicken has four toes, their first reaction is, ‘I never knew that.’ To be honest, I can’t blame them. 

Agricultural experts I’ve consulted on this matter noted that the development of extra toes (polydactylous chicken) is an unusual trait not just in chickens, but in the entire class of aves (a class of vertebrates which comprises birds).  

I’ll try to fit the jigsaw puzzle together. Generally, creatures with two legs and wings are called birds. Birds are the back- boned creatures with the ability to fly and to control body temperature. When birds are raised commercially for meat, egg or other features, they are referred to as poultry.  

Now, this is from the horse’s mouth: “Almost all birds have four digits (sometimes two or three) but rarely five or more”. Conversely, the bulk of the avian progenitors — reptiles — possess five and most mammals also have five toes. 

So, where did these polydactylous chickens come from? Your guess is as good as mine and the answer will depend on who you ask.  

I consulted the elders in Samia where I come from and this is what they told me, “We’ve reared these birds (namabasa in the local language) long before the coming of the white man.”  

Unfortunately, in most parts of Africa, information was passed on by the word of mouth and there’s little documentary evidence to confirm this.  

Elsewhere, the five-toed chickens first appeared in Latin literature in 37 BC.   

According to a paper by Elio Corti and his colleagues, the origin and historical distribution of five-toed chickens is not clear, although the birds are currently spread in Europe and Asia.  

EVERYTHING HAS ITS BEAUTY

It is also a well-known fact that the first domestic fowls came from Asia to Europe. The question that scientists are still grappling with is whether the five-toed chickens were brought from Asia to Europe or if they originated independently in these two parts of the world.  

Another thing is that only a few chicken breeds have a fifth toe as a distinctive feature. These breeds (Dorking, Silkie and Sultans) have polydactyly as a pure breed characteristic. In fact, if these breeds are born with four or six toes, this is considered a genetic fault.  

However, poultry breeders contend that sometimes this genetically controlled trait can also be unexpectedly found in some local populations and in breeds such as frizzles (F) and naked neck (Na) that I’ve written about in the past.  Apart from genetics, poultry breeders think that the expression of the five-toed trait in chickens could also be related to certain environmental factors. 

You see, scientists have proved that polydactylism can be suppressed or shifted to different phenotypes by exposing the developing embryos to low temperatures and injecting them with colchicine and insulin.   

What I found disappointing is that unlike traits such as naked-neck that confer advantages to other chickens (breeding a naked-neck with other chicken breeds improves the latter’s breast size, heat stress control, weight gain and feed conversion efficiency), the polydactyl trait doesn’t serve any useful purpose other than being a part of the breed’s standard definition criteria.  

I have a confession to make here. Unlike frizzles and naked-necked chickens, I’m hesitant to discuss the ornamental attributes of five-toed chicken after my farm manager retorted, “It looks odd and ugly!”   

But never mind, I told him that according to the great Greek philosopher, Confucius, “Everything has its beauty, but not everyone sees it.”