I was reading this article about subclinical or hidden ketosis and was surprised to find it suggest an average 30% rate of dairy cows in the UK testing positive with hidden ketosis. The first thing that struck me was the company which commissioned the audit also happens to be selling a product to test for hidden ketosis. Hmm!
Firstly were the cattle tested a fair representation of UK cattle? The audit tested 763 cows of the 2 million dairy cows in the UK from 15 different herds. While I would suggest a wider ranging audit would lend more weight to the results they have tested a reasonable number of cows.
Experts have proposed the prevalence of hidden ketosis within a herd can be influenced by season. The audit was conducted between July 2011 and January 2012 meaning the entire spring season was omitted. Whether this makes a difference is hard to judge until a consensus is reached by experts on the seasonal effects.
Finally I investigated the BHBA testing threshold for testing positive. In the Elanco audit they used a threshold of 1000-1400 µmol/litre. The lower end of this threshold is quite a low compared that proposed by other sources which suggest 1200 µmol/litre, 1400 µmol/litre, 1200 µmol/litre, 1400 µmol/litre. This would in theory produce results with increased positive tests.
One thing however that appears to be undoubted is that hidden ketosis is a real problem! Correctly monitoring your dairy herd is important from both a welfare and financial perspective.