Severe losses from acidosis

Feeding correct length fibre and avoiding grain overload is essential in preventing production loss from acidosis, says Ben Pedley

Acidosis is essentially a disease of ruminants where the pH of the rumen falls too low, into an acidic state. There are basically two forms of the disease producers should be aware of. First is the acute form. This is where the rumen pH falls rapidly, causing acute onset of illness. This is often caused by grain overload (gorging on barley, for example), which ferments quickly. This acid environment disturbs digestion and also damages the rumen lining, allowing the bacteria that normally live and remain in the rumen, to cross into the blood stream. This results in septicaemia, toxaemia and dehydration.

Affected animals can display a range of symptoms, but mostly they will appear off colour, often have a low temperature, sunken eyes, diarrhoea, a wobbly walk and if severe, unable to stand.

Ben Pedley, Willows Vet Group, Northwich, Cheshire

Treatment needs to be quick, and should include injectable antibiotics to treat the septicaemia plus oral fluids containing sodium bicarbonate powder to neutralise the acid. If so severe that they are off their legs then intravenous fluids will probably be necessary. Follow up care includes a high fibre with low concentrate diet. In any incident like this always consult your vet.

CHRONIC ACIDOSIS

Chronic acidosis is the other form. This is where the pH of the rumen falls over a period of time and not as low/not as acidic as the acute type. It can be caused by a diet short of fibre and too high in concentrates. Or where the concentrates are dumped in the rumen in one or two hits (eg, in the milking parlour, fed corn in a trough during the day).

This low level degree of acidosis gradually damages the rumen function causing weight loss, drop in production and eventually allowing rumen bacteria to cross into the blood stream. This can lead to numerous small abscesses in the liver, a condition often seen in cull cows at the abattoir. This liver damage can only be having a negative effect on production.

The effect of long fibre in the diet is to encourage the animal to spend plenty of time chewing, both when eating and cudding. The saliva produced contains huge amounts of sodium bicarbonate. As mentioned in the treatment of acute acidosis, sodium bicarbonate neutralises the acid, so it makes sense to get the animals to make it themselves all the time by encouraging plentiful saliva production.

Affected animals will show weight loss, loose faeces often accompanied by dirty, soiled rear ends/backs where the animals have flicked their tails in discomfort as they pass faeces, poor fertility and general ill thrift.

Diagnosis is usually by the presenting signs/symptoms, examination of the diet and sieving of the faeces for evidence of poor fibre digestion. When you are with your stock all the time this slow onset of a problem is easily missed. Sometimes it takes someone who has not seen your animals for a while to notice the gradual loss of condition, poor coats and dirty backs.

Treatment and prevention of chronic acidosis is mainly by dietary management and includes ensuring there is adequate long fibre in the diet, approximately 2-3in long; not too long otherwise the stock will sort it out if it’s straw and avoiding large dumps of concentrates as part of the ration. It is better to feed more corn if required via a TMR than via the parlour. It’s important to consult with your vet and nutritionist, ideally at the same time to review the diet and devise a ration that will avoid the pitfalls of acidosis without affecting production.