Ruminal Acidosis is where the pH of the rumen is lower (more acidic) than the ideal level.

It can be acute, where there are clinical problems which can be life threatening to the cow and require immediate attention or sub-acute which although not as immediately serious, this can actually have a much greater economic impact.

Acidosis caused by excessive intake of rapidly degradable carbohydrates such as starch and sugars found in concentrate feeds such as cereals.

The starch and sugar in these feeds is fermented by rumen bacteria largely to lactic acid. Lactic acid is up to ten times more acidic than other VFA’s produced during fermentation of fibre. This means that fermentation of these concentrate feeds causes the pH of the rumen to drop.

To ensure that acidosis doesn’t become a problem, it is important to ensure that there is enough fibre in the diet as this can help to reduce the likelihood of acidosis. When fibre ferments in the rumen, the VFA’s produced are much less acidic than when starch ferments and also, the ‘scratch factor’ of the fibre encourages rumination. During cud chewing, saliva is produced and this contains buffering chemicals which help to neutralise the acids produced during fermentation. A tip to ensure that there is enough physical fibre is to look at the ratio of forage to concentrates in the ration. There should not be more than 50% concentrates (dry matter) as this is likely to cause an excessive drop in rumen pH.

There are a range of symptoms of sub-acute ruminal acidosis (SARA) however some warning signs to look for are; Loose/runny manure, bubbles in the manure, Reduced cud chewing (there should be around 2/3 resting cows chewing their cud) and/or seeing cud balls in the cubicle head.

SARA can have a range of potentially costly impacts including Lower feed intake leading to reduced milk yield, lower butterfat and excessive loss of condition particularly during early lactation. This loss of condition can have a massive negative effect on fertility.

If SARA is suspected, the advice of a nutritionist should be sought, however a few things which may help include; adding a rumen buffer to reduce the acidity of the rumen, adding a yeast product which can help improve rumen fermentation and adding some chopped straw to the ration to add effective fibre thus stimulating rumination.