Scientists are inseminating dairy cows using the frozen sperm of DEAD bulls to stop them being wiped out by genetic weaknesses caused by inbreeding
- Scientists from Penn State University are breeding the new stock of dairy cows
- This is to ensure they have a good degree of genetic variation between them
- They say the animals may one day be needed to revitalise inbred dairy cows
- Genetic similarities put them at a far greater risk of dying of the same disease
Dairy cows in the US have become so inbred that diseases of the future could wipe them out in their millions, experts have warned.
Huge swathes of the cow population could be decimated as they all share a large part of their DNA and, consequently, the same vulnerabilities.
One scientist has warned that America’s nine million dairy cows are ‘pretty much one big inbred family’.
The ancestry of a large proportion of these cows fathers, 99 per cent to be precise, can be traced back to just two bulls, both born in the 1960s.
This lack of genetic diversity also means that we could hit a wall when it comes to selectively breeding desirable traits.
That means the improvements we have witnessed in terms of milk production, fertility and other attributes would stall.
Researchers say that a new injection of genetic material may be needed to prevent this from happening.
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Dairy cows in the US have become so inbred that diseases of the future could wipe them out in their millions, experts have warned. Huge swathes of the cow population could be decimated as they all share a large part of their DNA and, consequently, the same vulnerabilities (stock)
To find out if that’s the case, researchers from Penn State University (PSU) are now breeding new cows using the semen of long dead bulls.
They plan to take measurements of their key characteristics and compare them to today’s Holstein dairy cows – including their height, weight, production of milk, fertility and overall health.
They hope that, if the day ever comes that fresh blood is needed to revitalise dairy cows, these genetically varied cows could provide the necessary DNA.
‘What we’ve done is really narrowed down the genetic pool,’ said Chad Dechow, associate professor of dairy cattle genetics at PSU, told Scientific American.
‘If we limit long term genetic diversity of the breed, we limit how much genetic change can be made over time.’
The lack of genetic diversity in dairy cows also means that we could hit a wall when it comes to selectively breeding desirable traits. That means the improvements we have witnessed in terms of milk production, fertility and other attributes would stall (stock image)
There are two main breed of dairy cow used in farming, the Holstein and the Friesian.
Holsteins are large cattle with coat colour patterns of black and white or red and white and are mostly found in the US.
British Friesian cattle look similar but are generally slightly smaller than Holsteins and carry more flesh.
Holsteins produce an average 1,600 gallons (7,330 litres) per year, with pedigree animals averaging 1,890 gallons (8,600 litres).
The average milk production of pedigree British Friesians currently stands at 1,320 gallons (6,020 litres) per year.
Previous research conducted by PSU in 2015 revealed that their are just two variations in the Y chromosomes of most modern Holstein bulls.
The study also revealed that there is so much shared DNA in females that there is an effective population size of just 50, a size so small that the species would be considered at critical risk of extinction, where they living wild.
‘It’s pretty much one big inbred family,’ said Leslie B Hansen, a Holstein expert and professor at the University of Minnesota.
