Friday, 26 January 2018 10:55

Breeding for heat tolerance

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Australian farmers can now look for bulls that increase heat tolerance. Australian farmers can now look for bulls that increase heat tolerance.

Australian dairy farmers can now add breeding to their ways of helping cows handle the heat.

DataGene, Australia’s independent and industry-owned organisation responsible for developing the means of increasing genetic gain and herd improvement, has released a world-first -- Heat Tolerance Australian Breeding Values (ABV).

Dr Matt Shaffer, DataGene chief executive, says that although environment and management conditions have a big impact on a cow’s response to heat, genetics also play a role.

“Advances in genomics allowed our Dairy Bio team to identify gene markers for heat tolerance. 

“The Heat Tolerance ABV allows farmers to identify animals with greater ability to tolerate hot weather with less impact on production,” he says. Dairy Bio is a joint initiative between the Victorian Government and Dairy Australia.

Dairy Australia’s advice is that to breed for improved heat tolerance, look for bulls with a high balanced performance index (BPI) and a Heat Tolerance ABV greater than 100; use several bulls to allow for the lower reliability.

The reliability of the Heat Tolerance ABV is 38% which is in line with the newer generation of genomic-only traits. Like all new ABVs, reliability is expected to improve with time, as more data becomes available.

Heat tolerance is favourably linked with fertility and unfavourably with production; this means a strong focus on heat tolerance bulls may improve fertility but compromise production.

“If breeding for heat tolerance, look for the exceptional animals that are strong for both BPI and heat tolerance,” Shaffer says.

While not all dairy farmers will want to include heat tolerance in their breeding priorities, some are keen to get started.

Farmer Trevor Parrish, Kangaroo Valley, NSW says he will be looking for bulls that increase heat tolerance.

 “Now when I get a list of bulls I’m going to be looking for bulls which combine increased production and increased heat tolerance; they will be the ones that buck the trend,” Parrish said.

Parrish’s family milks 160-240 cows year round and sells bulls to semen companies and other dairy farmers.

Farmer Ray Kitchen of Carenda Holsteins, Boyanup, WA says having a Heat Tolerance ABV will mean he can breed cows with a greater ability to tolerate hot weather and be better suited to his farming environment.


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