Spring grass poses acidosis risk for dairy cows

Dairy farmers turning cows out to spring grass are being urged to guard against an increased risk of acidosis and drop in butterfat.

Provimi’s ruminant technology manager Philip Ingram says because spring grass is rapidly digestible, fermentation acids are produced much faster than the digestive system can clear them.

He says this can result in acidosis as well as an upset in normal intake patterns. This is a major contributory cause of reduced butterfat at grass, but it can also lead to lameness and poor fertility, he adds.

Studies show acidosis in grazing diets is more prevalent than generally realised.

A recent university study in Ireland found 11% of grazing cows had acidosis while 42% were marginal.

“In most years, producers will start by turning out cows for part of the day and buffer feed at the same time,” says Dr Ingram. “This helps to condition the rumen and avoids an acid overload that can cause acidosis.

“But due to low forage stocks this spring, I can see the transition from winter rations to grazed grass will be faster this year. Also, we’re likely to see spring grass catch up on lost time and grow very rapidly. So the risk of acidosis and reduced butterfat could well be much greater,” he warns.

Mr Ingram advises dairy producers to buffer feed forages to help guard against the effects of acidity from rapidly digested grass.

If forage supplies are limited, Dr Ingram says producers should use a rumen buffer, which will help to bolster the cow’s natural buffering ability.

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