LIC scientists have discovered new genetic variations which can impact a cow’s ability to carry a calf to full term.

The variations are known as Fertility2, Fertility3 and Fertility4, and are carried by about 2% of Holstein-Friesian dairy cows and 1% of crossbreds.

LIC chief scientist, Dr Richard Spelman, said it follows the 2013 discovery of Fertility1 in the Jersey breed and concludes 18 months of DNA sequencing research which focussed on fertility and calf survival.

“All three variations have the same effect on fertility and calf survival, with origins in the New Zealand dairy cow dairy population dating back to sires born in the 1970s.

“These are recessive genetic variations which mean an embryo will be non-viable if both the sire and dam have a copy of the variations and pass them on; even if both parents are carriers, only one in four of their progeny will be affected.

“When an animal has two copies of the variations the animal will die in utero. Our research shows that the cow carrying this foetus will then be empty, which means it will not lactate the following season. No live animals have been seen with two copies of the variation.”

The farmer owned co-operative, which supplies genetics to breed approximately three-quarters of the national dairy herd, has published a list of its artificial breeding (AB) sires that carry the variations on its website (www.lic.co.nz).

The information has also been added to the co-op’s Datamate technology, which its AB technicians use before insemination to check inbreeding potential or any lethal gene combinations with a dam and sire.

DataMate will issue alerts to reduce the frequency of matings between two carriers of the variation, as it does already with Fertility1 and other undesirable genes including CVM, BLAD and Small Calf Syndrome.

“These variations will have little impact on a farmer’s mating decisions this spring, but what they do provide is a solid genetic explanation for why some calves do not survive through to birth, resulting in an empty cow.

“It allows farmers to make more informed decisions to manage and minimise this risk on their farm.”

The variations were discovered as part of LIC’s DNA sequencing programme, which aims to map variations in genes in a cow’s DNA that can impact production and health.

It utilises a large sequencing dataset developed by LIC scientists and co-funded by the Ministry for Primary Industries through the Transforming the Dairy Value Chain Primary Growth Partnership programme, led by Fonterra and DairyNZ.

The programme has led to previous discoveries including the Small Calf Syndrome gene, a fat gene which impacts milk composition and a variation which impacts a cow’s ability to regulate body temperature and cope with heat stress.

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