Scientists at the genetics co-operative Livestock Improvement (LIC) believe they have found the gene responsible for a small number of unusually small calves appearing in dairy cow herds over at least four decades.
The discovery was made within the last two weeks.
Dairy farms commonly lose between two and four per cent of calves each year for a variety of reasons and this discovery was made as part of LIC's ongoing research to understand whether there is a genetic basis to these losses.
The gene variation discovered explains a small proportion of those losses.
LIC believes the variation has existed within the dairy cow population for at least 40 years. The frequency of the gene variation is 10-15 per cent in Holstein friesian cows, and half that in crossbred populations.
When both parents carry the variation there is a one in four chance that the progeny will be small.
The discovery of the variation was accelerated because of LIC's ongoing investment in DNA sequencing technology. The knowledge gained will enable the variation to be managed out of the population over time.