A significant number of ketosis cases are going undiagnosed because blood samples are being taken at the wrong time post-calving.

Edinburgh University analysed a sample of 42,734 blood samples from 1,203 herds in the UK and Ireland for indicators of negative energy balance.

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Results showed 30% of cows developed subclinical ketosis in early lactation, costing on average £210 a cow.

However, in many herds it goes undiagnosed because people are either failing to test or are testing too late, Dr Alastair MacRae, from the university, told delegates at the North West Dairy Health and Welfare conference in Preston last week.

He said the first three weeks of lactation is a crucial stage to be monitoring for ketosis, but in some circumstances blood sampling is being left until four to five weeks post-calving.

He added: “The problem with doing that is you have cows with normal results because you missed the stage of negative energy balance.”

Blood sampling will help prevent subclinical ketosis in the next group of calvers, because it will give farmers the opportunity to correct diets or increase intakes, he explained.

Instead he advised blood sampling dry cows within days of calving and fresh calvers between 10 and 20 days calved.

He added: “You shouldn’t just look at the blood samples in isolation. You need to look at diet, feed management and speak to your vet and feed adviser to see where the problem lies and try and get on top of the problem.”

Common causes for ketosis:

  • Inadequate energy in the diet
  • Inadequate feed intakes
  • Poor use of energy in the diet (too much sugar and starch)
  • Overfeeding dry cows