Balance feed to avoid acidosis

As many as half – if not more – of UK dairy cows are thought to be suffering from Sub-Acute Ruminal Acidosis, which is eroding farm profitability.

Optimal rumen health is critical for feed utilisation and dry matter intakes, and so it has a direct impact on milk yields and constituents, says Adam Clay, DairyCo extension officer. The ideal rumen pH is between 6 and 6.5, and although this will fluctuate throughout the day, just two hours below a pH of 5.8 can result in Sub-Acute Ruminal Acidosis (SARA).

"SARA depresses production and appetite, and can create a vicious circle of falling pH in the rumen," explains Mr Clay. "If acids pass through the rumen wall they cause metabolic acidosis, which in severe cases can lead to shock and death.

"The type of feed has a direct impact on the effectiveness of the rumen. Low energy diets can reduce the absorption of nutrients, and this means that your cows won’t be utilising feed efficiently.

"Forage quality in the diet is also important, as it encourages more cudding, which stimulates saliva production, an important element in rumen buffering. Excessive amounts of concentrates, on the other hand, decrease rumen pH, reduce feed intake and microbial production and depress butterfats.

"The ideal ratio of forage to concentrate feed is 60:40 on a dry matter basis, and rations should be well mixed to avoid selective feeding. Cows burrowing through the longer fibre to get to the palatable concentrated feeds are more likely to get SARA, so it is important to balance the need for a decent forage chop length with the need for a unified feed."

To help prevent acidosis, producers should spread balanced forage and concentrate feeds over the day, provide starchy feeds little and often, and limit parlour concentrate feeds to between 4kg and 4.5kg per milking. They should also ensure separately fed forage is of a good quality and available ad-lib, and encourage maximum saliva production with salt or salt licks and adequate water.

"Metabolic disorders can invariably be prevented by ensuring the best possible dietary balance and particularly careful management of cows at drying off, during the dry period and in early lactation.

DairyCo is running feeding+ events on dry cow management across the UK. To find out more visit www.dairyco.org.uk or call 02476 478684.