A new method gives the first reliable indication of whether cows have been given illegal growth hormones, says Susann Ludwig from Rikilt in her doctoral thesis, which she will be defending on 23 June.
Foto credit: b3d_
Growth hormones increase cows’ milk production by 10 to 20 per cent. Even so, the treatment has been banned in the EU since 2000 as the injections cause suffering to the cows and increase the risk of udder infections, for instance. However, it is difficult to enforce the ban as there is no reliable test. ‘So we have no idea how big the problem is,’ says Ludwig. ‘It could be widespread or it could be non-existent.’
It is difficult to detect the use of growth hormones because the artificial hormones are almost identical to the body’s own version. Ludwig solved this problem by looking for four biomarkers in the blood rather than the hormone itself. These proteins, which are found naturally in the body, are produced in different quantities if you inject extra hormones. These changes are indirect evidence of hormone treatment. Ludwig got inspiration for this approach from the efforts to track down human doping cheats.
Ludwig can now use her method to detect about 95 per cent of treated cows. This result makes her the first to to satisfy the requirements set by the EU for such tests. Although the method also tests positive for 12 per cent of the ‘innocent’ cows, Ludwig does not see this as a problem. For legally sound proof, her test results would have to be confirmed anyway by another (more expensive and complex) method.
Meanwhile, Ludwig is looking at a measurement method that is even cheaper and simpler. In addition to her lab method, which uses blood, she shows that you can also detect hormones using cow’s milk and simple tools. Together with an American research group, she built a small device with a port for a mobile phone. An app carries out the actual measurement of the milk sample. ‘A phone like that has everything you need,’ says Ludwig. ‘And it’s relatively cheap and everyone knows how to use it.’