Vet on Call: Why cows turn red or yellow

Friday November 03 2017

Deficiency of many trace minerals will cause some copper deficiency-like symptoms in cattle such as poor growth, apparent malnutrition, repeat insemination and poor reproduction performance. PHOTO | JOSEPH MUGACHIA | NATION MEDIA GROUP


Greg loves cattle, especially the Friesian type. He finds their shiny black and white colour soothing and hypnotic.

Unfortunately when he started keeping his Friesian cows a year ago, they gradually turned into a rough faded black before completely changing colour to reddish.

In addition to the red colour, the calves were growing slowly while the mothers failed to get heat.

The problem did not resolve even after he increased the amount of feed each cow consumed daily.

Two of the cows also had some grey hair around the eyes despite their young age.

He called me to investigate the situation and advise him.


In the course of my practice, I have seen many animals with problem such as that of Greg’s.

The anomaly is widespread among zero-grazed cattle in Kenya.

Farmers do not consider it an issue until heifers fail to get on heat and the fertility of mothers declines.

Most farmers tell me they think the colour change is due to the red soil usually used in the sleeping cubicles of zero-grazed cattle.

In any case, the cows initially appear normal with only a red hue on the coat before eventually turning red.

When I examined Greg’s cows, three had diarrhoea.

There were two adult heifers that had failed to get on heat.

The cows were being fed on hay and dairy meal but no mineral salt mix.

The colour change he had described to me as red was actually copper brown.

I diagnosed copper deficiency and advised him to add mineral salt mix from a reputable company in their feeds.

The cows started getting back their normal black colour in two weeks and fully regained it after two months of salt intake.

They also came on heat and the calves increased their growth rate.
Copper deficiency is not always as easy to diagnose and treat.


For confirmation of diagnosis, I could have taken samples from the cattle or feeds for laboratory analysis.

However, the process is long and expensive.

My close to 30 years of practice shows that this condition responds well to treatment with mineral salt mix containing the recommended quantity of copper.

If my prescribed treatment had been unsuccessful, I would have taken feed and tissue samples for copper content analysis.

Copper is a heavy metal element which has very important functions in the cow’s body.

These include building immunity, growth and reproduction.

Copper gets into the body mainly through the food the animals eat and the water they drink.

Feeds from some areas have low copper content.

Their intake results in what is called primary or absolute copper deficiency.

In some cases certain elements in the feed, if present in high concentrations, may interfere with availability of copper to the body.

The elements may form fairly stable complexes with copper and prevent usage of the mineral by the body.

This is termed as secondary copper deficiency because the levels of copper in the blood may be normal but the mineral itself available for use by the body is below average.

Some of the elements that reduce copper availability to the body are iron, zinc, molybdenum and sulphates.

The treatment I prescribed for Greg’s cattle is called symptomatic because I based the diagnosis on the signs of copper deficiency I observed.

When symptomatic treatment fails, a doctor is required to take samples of the various feeds the animals eat and the water they drink and subject them to laboratory analysis for copper levels and the concentration of substances that interfere with copper availability.


Liver samples, called biopsies, are also taken to determine the concentration of copper available to the body.

Blood samples are not good for diagnosing copper deficiency because, as earlier mentioned, the copper in the blood may be bound in complexes that render it unavailable for utilisation by the body.

The tissue biopsy can only be taken by a veterinary doctor.

Not all cattle with copper deficiency will turn red.

Red and brown cows such as Ayrshires and Guernseys will turn yellow when they have copper deficiency.

Due to the role of copper in building immunity, deficiency of the element makes animals respond poorly to vaccination and they are open to contracting diseases easily.

Some animals also get long curly hair because of their inability to properly utilise other nutrients such as proteins, fats and carbohydrates.

The animal may therefore appear to be malnourished but in fact the problem is copper deficiency at the primary or secondary level.

Low blood level, called anaemia, may also occur in some animals because copper helps in absorption of iron which aids in formation of blood.

Some animals will have weak bones and easily get fractures.
Copper and other minerals are called trace or micro-minerals in the cow’s body.

They interact with each other and body chemicals such as hormones and enzymes to ensure proper functioning of the body.


Other trace minerals include chromium, cobalt, iodine, iron, manganese, molybdenum, nickel, selenium and zinc.

Always ensure that mineral salt mixes you feed your cattle contain these elements.

Their concentration in the product should be clearly indicated on the product label.

Deficiency of many trace minerals will cause some copper deficiency-like symptoms in cattle such as poor growth, apparent malnutrition, repeat insemination and poor reproduction performance.

Unlike diseases caused by micro-organisms, nutritional disorders from trace element deficiencies give the farmer time to adjust the feed and correct the deficiency long before the animal gets too sick.

An observant farmer will always notice changes in the coat colour of their cattle.

As a general rule, all cattle should have a shiny hair coat regardless of the colour.

Except for long-haired breeds of cattle, others have short hair that lies smoothly on the skin and only falls off in very small quantities as the hair ages and are replaced by new ones.

Should a farmer notice changes in the hair colour of a cow but it looks generally normal, then the first thing to do would be to review the feeding.

Signs of recovery should be visible in two weeks of corrective feeding.

If the symptoms persist after two weeks, the farmer should consult a veterinary doctor.