REDUCING genetic diversity means that dairy cattle are now becoming more closely related, said Edinburgh Universitys Tim Roughsedge. Studying Holstein Friesian breeding in the UK over the last 30 years, he concluded that fewer animals are contributing more as time passes, reducing genetic diversity of the population.
His study found that in 1997, one bull contributed 5% of the average Holstein Friesian cow genome. "Heavy reliance on few selected individuals as sires will inevitably lead to a further decrease in genetic diversity. This should be accounted for in future selection programmes."