Breeding better cattle

The 1,000 bull genome project is mining the genetic gold that will raise the productivity and health of our herds. Elizabeth Finkel reports.

La Trobe geneticists are looking to speed up the process of making cattle more productive. – iStock

La Trobe geneticist Ben Hayes is on a modern day treasure hunt. He leads the international 1,000 bull genomes project, searching through the DNA blueprints of bulls for the secrets of how to breed healthier and more productive cattle.

It’s a process we’ve been engaged in for 10,000 years, since we first domesticated the wild ox, or auroch, in a region near modern Turkey. Modern breeding techniques have raised cattle productivity about 1% per year by selecting the best performing parents, particularly the best bull whose sperm can sire a million offspring. But the process is slow. For each generation of dairy cows, breeders must wait five years before they can identify the best performers. The bull that sired them would then be used for breeding, until the next five-year cycle identifies an even better bull.

Selecting the best bulls directly based on their own DNA
sped up the breeding cycle threefold.

Back in 2001, Hayes and his colleague Mike Goddard at the University of Melbourne came up with a method for speeding things up. Instead of waiting to test the bull’s DNA through his daughters’ performance, it should be possible to test it directly using “genomic profiling”.

“It was purely a theoretical paper,” says Hayes. The cost of reading DNA made it impossible at the time. But technology caught up and by 2008, bull breeders were beginning to adopt it. Selecting the best bulls directly based on their own DNA sped up the breeding cycle threefold. Hayes estimates that bulls in Victoria now improve at a rate of 1.5% per year.

But there’s more to be gained. Genomic profiling is a low-resolution way of looking at the genome, like reading the occasional sentence in a book of three billion letters. To see the fine details requires reading every letter of the three-billion-letter bull genome. The 1,000 bulls project aims to read 1,000 genomes to unlock the full genetic treasure of this species.

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