My search for yellow-yolked eggs bears fruit

Friday April 15 2016

Free-range chicken look at an egg on a farm in

Free-range chicken look at an egg on a farm in Seefeld, southern Germany, on February 25, 2013. Authorities in Germany said a probe had been launched into farms in the northwestern state of Lower Saxony suspected of selling eggs as "organic" but not adhering to the conditions required for the label. AFP PHOTO| VICTORIA BONN-MEUSER  

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From my experiences in selling poultry products, I have come to learn that customers are interested in buying items with special attributes.

One thing my customers have always complained about is the diminished “yellowness” of the egg yolk. In fact, one customer who was buying about 10 crates per week negotiated a lower price of

Sh10 per egg instead of the usual Sh20 because her clients were complaining the egg yolk was not “yellow enough”. I accepted because I didn’t have a choice.

Now, here is the puzzle I have been struggling with. You see, eggs of indigenous birds raised under free-range have yellow yolk. Because of space, I rear my Kari Improved Kienyeji chicken under

confined conditions and only allow a few birds to free-range a few days a week.

I formulate my own feeds and this saves me between 30 and 40 per cent for every 70kg bag. For energy sources, I use maize germ and wheat bran. For proteins, I use soya cake and sunflower


I then add amino acid supplements (concentrated building blocks of essential proteins) in form of lysine and methionine, and vitamins and minerals in form of premix. I select the ingredients

correctly and mix in the right ratio. I have also tested the raw materials for quality. From these ingredients, the birds receive a balanced diet. So, why is the yolk not as yellow as some of my

customers would prefer for Kienyeji eggs?

Now, to be honest, this problem has caused me sleepless nights as the low price for the eggs has been eating deep into my profits, and yet the layers alone consume about 45kg of feeds daily. All

along, I had suspected that chickens raised under free-range consume ‘greens’ that make the yolk yellow.

So, to solve this problem, I instructed my manager, Cleopas, to undertake a few ‘experiments’. But up to that point, I had no idea the specific chemical in the ‘greens’ that is responsible for making

the yolk yellow.


To start with, I have plenty of green grass I planted around my coop and the first experiment was to cut the grass and give the birds. I waited for two weeks. Nothing happened. The yolk was not

yellow. The next obvious choice were vegetables sold in the local market like cabbages, sukuma wiki (collard green) and spinach. I asked my manager, Cleopas, to undertake a market survey and

give me the price comparisons. He visited a few markets in Njiru and Marikiti.

I opted for cabbage because it was the cheapest of the three. A bag of sukuma wiki and spinach retails at Sh2,000 and Sh3,000 respectively. For two weeks, he fed the birds on cabbage. Nothing

happened. I was frustrated.

Was he selling the cabbages instead? Well, one thing I can say about Cleopas is his sense of duty and honesty. Although my principle is to trust but verify, I have never had to doubt him. In fact, he

remits all monies from sales on the farm and retains his 10 per cent commission as part of our agreement. So, what was the problem?

Two weeks ago, I decided to consult my brother Dr Silas Obukosia, the agricultural biotechnologist. The scientist didn’t mince words. “Cabbage doesn’t contain any Beta-carotene. Beta-carotene is the substance that contributes to the orange colour of many different fruits and vegetables,” he texted.


You see, Beta-carotene is one of a group of red, orange, and yellow pigments called carotenoids that give fruits and vegetables their orange pigment.
Although the mineral can be found in fruits, vegetables, and whole grains, the highest sources of Beta-carotene foods are sweet potatoes, carrots and dark green leafy vegetables like spinach and

sukuma wiki, in that order, Obukosia explained.

After this conversion, I instructed Cleopas to isolate a few birds, crush some carrots in a blender and put in their drinking water. After five days, he called with this news.

“I have noticed a drastic change in the colour of the yolk.” I couldn’t hide my excitement.

Later, when I spoke to a nutritionist in our office, she explained that for a fact, Beta-carotene and other carotenoids provide approximately 50 per cent of Vitamin A needed in our diet.

“When we consume foods rich in Beta-carotene, the human body converts it into Vitamin A, also known as retinol,” she said.

She explained that vitamin A is an essential nutrient, meaning, it cannot be made by the human body from scratch and must be obtained from dietary sources like eggs and sukuma wiki. It

contributes to our healthy skin and mucus membranes, improves immunity against diseases and contributes to good eye sight.

It was clear from her explanation that chickens need a diet rich in Beta-carotene to transfer that source to their eggs, which, in turn, is good for humans.

When I consulted Kennedy, a poultry farmer and a practising vet, he informed me that there is a synthetic form of Beta-carotene that is made in the laboratory. He said adding it to layers mash

makes the egg yolk yellow.

I have asked Cleopas to look around for it. I am interested in several things, the price compared to carrots, sukuma wiki and spinach and how much should be added to the feeds. When I find it, I

will try it out and share the results. I am also experimenting with sukuma wiki, spinach and sweet potatoes.