Urea Poisoning
By Dr Mackie Hobson BSc(Agric),BVSc

1. Poisoning
2. Nutrition

Urea poisoning can occur when Angora goats take in excess amounts through a lick or if a lick gets wet (urea dissolves easily in water).

How much urea can I feed an Angora goat?

The maximum levels of urea tolerated by an adult Angora goat is 15g/day.

Goats should be adapted over 2-3 weeks by increasing the urea level slowly.

If they do not receive urea for a gap of 2-3 days then again an adaption period is needed.

Remember the % is the same a g/100g so a feed with a urea content of 3 % equates to 30g/kg feed. A urea content of over 3% can be considered high.

An intake of 25-45g could potentially kill a goat within an hour.

Why is urea included in a lick?

All proteins contain on average 16% Nitrogen (N) whereas urea contains 45% N. In order for it to be utilized by the rumen microbes it must first be chemically combined with water to form carbon-dioxide and ammonia. This reaction is accomplished by action of the enzyme urease derived from certain rumen microbes.

Ammonia is toxic but in a normal rumen this ammonia is broken down to ammonium which is used by the rumen bacteria to form bacterial protein which the goat can use.

Is urea feeding always beneficial?

 J.Hoon and J Van Rooyen showed that excess urea (4%) can have a negative effect on reproduction in trials conducted with Angora goats.

Milk production of ewes at 3 to 4 weeks after lambing did decreased with an increase in urea inclusion level, resulting in lower body weights of the 4% Urea group at 42-day age. A lower conception rate was also recorded in the next breeding season for ewes receiving higher inclusion levels of urea, indicating a possible carry-over effect from the feeding treatments applied during late pregnancy and lactation.

Why does excess urea intake lead to poisoning?

If excess urea is taken in by the Angora goat the pH of the rumen increases (alkalosis) which may be as high as 8 in some cases. This high pH does not allow the conversion of ammonia to ammonium by the rumen bacteria. The increase in ammonia leads to increased blood uptake of ammonia causing an alkalosis (increased pH) of the blood and body tissue of the goat.

Maximum amounts of urease enzyme (produced by certain microbes)  are produced at pH 6-7. For this reason carbohydrates are fed with urea and also provide energy for the microbes

What symptoms can be seen in goats with Urea poisoning?

Clinical signs and death can occur from 30 minutes to 2 hours after ingesting excess urea

Due to the brain being affected we can see neurological signs:

• Shivering
• Staggering
• Tetany signs developing into a coma before death

Gas production in the rumen leads to:

• Bloat
• Difficult breathing (oedema of lungs)
• Foam from nose and mouth

In chronic cases goats may just show signs of a poor appetite, lethargy or poor production.

Post Mortem findings

• Bloat
• Lung oedema and foam
• Trachea filled with foam
• pH of rumen alkaine (High as 8, Usually 6.2-6.8)
• haemorrhages on intestine and rumen wall

Treatment

Dilute 1 litre Vinegar with 2 litres water (1:2) and dose or tomach tube 0.5-2 litres.

Repeat after a couple of hours

REFERENCES

Kleinvee-siektes , De Wet and Bath

Merk Veterinary Manual: Larry J. Thompson, DVM, PhD, DABVT, Senior Research Scientist

1. Hoon and J Van Rooyen, Grootfotein