Vet on call: Deadly foe that can quickly kill your cows

Last week, I was inundated with phone calls, texts and WhatsApp messages from readers and farmers.

They wanted to know why animals could eat a commercial feed supplement and soon start acting strangely, then drop dead one after the other.

The sight on the photos and videos circulating in the media was appalling. The reports said the legislator for Emurua Dikirr had lost 24 head of pedigree Friesian cattle within minutes of feeding them with an imported feed supplement. Animals that were not fed the product were alive and well. 

One farmer from Uasin Gishu asked me, “Could this be fake news?” I responded that the story looked real since the claimants to the occurrence were clearly captured in the photos and even mainstream media were reporting it.

The purported culprit feed product was also presented. What I never told the farmer is that I knew about the product and its formulation.

My revelation would have amounted to declaring the product culpable without a proper diagnosis. That would have been unprofessional and unethical on my side.

I further explained to the farmer that the issue was grave and required investigation by the Director of Veterinary Services (DVS) and the Kenya Bureau of Standards (Kebs), who are responsible for the quality, safety and use of animal feeds.

I later came to understand the DVS and Kebs are carrying out their investigation. In addition, the regulators have ordered that the product be pulled off the market pending completion of the investigation.

It is an imported urea supplement that is supposed to enhance production performance of ruminants including cattle, sheep and goats.

Another farmer from Nyandarua asked me if I thought urea poisoning could have been the problem.

I confirmed to the farmer that urea poisoning could cause the kind of signs highlighted in the reports but it was not the only chemical that could kill dairy cattle so suddenly and in large numbers soon after consumption. Nitrates and nitrites could cause similar poisoning.

So, how does urea cause poisoning in cattle? My professor of ruminant production, many years back in training, cautioned us that the ruminant stomach is a huge biological and chemical factory.

UREA POISONING IN CATTLE

The largest of the four ruminant stomachs is the main production unit. He further explained that urea is the main ingredient in the production of proteins in the ruminant.

However, when urea is fed as a chemical in the feeds in excessive quantities or in inappropriate methods, it quickly kills the animal. “You can feed urea and the animals start dying before you get back to your car,” he cautioned.

In the course of my practice, I have seen cases of urea poisoning in cattle following the use of urea in silage-making or accidental consumption of urea and ammonia-containing fertilisers.

I always advise farmers to engage animal nutritionists or use products with very clear instructions whenever they use urea as a feed component.

All animals require proteins for body building, maintenance, production and reproduction. Proteins, once ingested, in both ruminants and simple-stomach animals, are broken down into absorbable components called amino acids.

In simple-stomach animals like humans, dogs and pigs, the proteins are directly broken into amino acids during digestion and then absorbed into the body where they are built into the myriads of desired proteins.

Ruminants, on the other hand, have a tortuous way of producing amino acids; and herein lies their sensitivity to urea poisoning.

The rumen contains billions of micro-organisms that first convert ingested proteins to urea. The urea is further broken down to ammonia. The micro-organisms then use the ammonia to produce amino acids.

Finally the amino acids are moved into the lower gastrointestinal tract where they are absorbed into the body to make proteins.

Ammonia is volatile. If produced in quantities higher than the micro-organisms can utilise, it is absorbed into the bloodstream and transported to the brain.

It blocks brain function and causes the signs of salivation, teeth grinding and uncoordinated movement. There is also difficult breathing, protrusion of the eyeballs, collapse and death.

RAPID PRODUCTION OF AMMONIA

Signs of poisoning occur soon after ingestion of urea and in most cases death occurs quickly.

Animal scientists long discovered that the ruminant protein production process can be shortened by feeding the animals directly with urea.

This increases the production performance of the animal because amino acids, and hence proteins, are produced faster and more efficiently. 

The interference with a natural biological process always requires specific adaptation to the change.  

That is why we advise farmers to introduce new feeds slowly to give the rumen time to detect the change and increase the population of the micro-organisms that digest the new feed.

In the case of urea feeding, the rumen requires time – from five days to about two weeks – to increase the numbers of micro-organisms that utilise the ammonia produced from urea breakdown and prevent ammonia poisoning.

Cattle farmers must note that adaptation by the cow to safely utilise urea is lost in 1-3 days if urea feeding is withdrawn. 

Animals well adapted to urea feeding can safely consume up to 1g of urea for every kilo of body weight daily; but the same easily kills a cow that is not adapted.

Urea introduced gradually at the rate of 0.3 to 0.5g for every kilo of body weight daily is known to be safe to cattle.

It is good to note that even safe levels of urea given to cattle at once can cause poisoning due to the rapid production of ammonia in large quantities.