The study of their DNA by Scotland’s Rural College was carried out at the Crichton Royal Farm in Dumfries.
It found telomeres - which protect the end of chromosomes - deteriorate the most soon after birth, indicating how long and healthily an animal may live.
It could help human geneticists looking at how to prolong our life expectancy.
Work suggests that telomere length in humans affects ageing in as much as young humans have long telomeres and old humans have short telomeres.