Currently in the Karoo, we are experiencing one of the worst droughts. Plants, animals and humans are suffering due to this drought. The result is, that most sheep (and other small stock) does not graze the veld anymore, but have to be kept in kraal and fed. This in itself brings about a multitude of problems.
I have seen many sheep the last couple of months that have developed rumen acidosis. The result is the loss of sheep or, if they recover, problems such as laminitis. The most important aspect to remember is: If you farm with a ruminant, you are in fact farming with the rumen and the organisms in it. The rumen is basically the motor that keeps the animal running. If the motor dies, the animal dies.
The normal pH of the rumen must be between 6.4 and 6.8. With any low fibre carbohydrate (Maize, wheat, low fibre molasses, oats, barley, sorghum etc.) there is a high risk of developing rumen acidosis if these are not fed in the right ratio with other feeds (especially fibre) or with the intake of an excessive amount. These carbohydrates are fermented in the rumen and lactic acid is produced. Lactic acid drops the pH of the rumen and in turn the pH of the blood drops which leads to organ failure.
We all know the words: “Prevention is better than cure” In the case of rumen acidosis it is very true. Rumen acidosis can be prevented by remembering and implementing a few important managing aspects:
1. The organisms in the rumen take 3 weeks to adapt to any diet changes, but they lose their adaptation in 3 days (this is also important to remember when feeding urea). This means that a gradual adaptation to feed is required and a consistency in frequency of feeding. Example: Start week 1 with 50g of maize per animal every second day, 100g week 2, 150g week 3 and stick to feeding every second day (this is only an example).
2. Make sure there is enough feeding space. All the animals need to feed simultaneously. Example: If you have 150 sheep do not provide feeding space for only 50. Some animals will consume feed in excess and will develop rumen acidosis. It is usually the dominant sheep that develop rumen acidosis because they keep the weaker ones away from the feeding trough.
3. Ensure that there is enough roughage for the animals. Remember you are farming with a ruminant (sheep, cattle, goats, most game species – antelope, giraffe, buffalo etc.) and not a pig. Ruminants were created to convert poor quality roughage to meat and wool. Any supplementary feeding (such as pellets, maize etc.) must be given with wisdom and caution.
When an acute case is encountered, quick action needs to be taken. Feed lime is the cure most readily available to the farmer and must be given orally to counter the acidic pH. If you only have bicarbonate of soda, it can also be given, but remember it produces a lot of gas and can cause bloat.
In future I will elaborate on the adverse side effects after recovering from rumen acidosis and the effects of chronic rumen acidosis.
Dr. Bennie Grobler