warming climate is a big problem all around the world that’s not going to go away. However, the dairy industry can look to nature to find genetic solutions for a warming climate, such as the Slick gene which gives cows greater heat tolerance.

“This gene was in three indigenous breeds that have had natural selection pressure on heat. It’s a good lesson that we can look to nature and find things that we can breed into our dairy herd,” Thermo Regulatory Genetics chief executive Derek Fairweather says.

The Slick gene, named because cattle who inherit the gene have very short hair and appear shiny and wet, keeps cows up to 1C cooler than other cattle and is enough to make them perform significantly better in hot and humid temperatures.

Slick gene cows milked on DairyNZ System 5 farms could potentially produce up to three litres/day more during the summer months, Derek says.

“A lot of System 5 farmers have bred US or Dutch Holstein Friesians, and they’re the cows that are hurting.”

Research by the University of Florida has shown United States Holsteins under heat stress with the Slick gene can produce 3-4 litres a day more.

There is still work to do around quantifying that in a New Zealand context, but NZ farmers milking big Holsteins in System 5 operations could expect to produce an extra 3l/day from cows with the Slick gene, Fairweather says.

Thermo Regulatory Genetics has a team of 70 bulls in NZ and another bull team in the US, and has been selling straws to US farmers and farmers in tropical countries for several years.

They are now also turning their attention to the NZ market. The company has started to customise bulls to sell semen in NZ and is aiming to have 10,000 daughters with the Slick gene on the ground in NZ in the next year or two.

Their priority is to gather NZ data from these daughters, which will be easier to collate than from tropical countries.

There is growing awareness of the impact of heat stress amongst the industry, Derek says.

Fonterra’s new Animal Welfare Code specifically identified heat stress and identified the Slick gene as a potential solution.

Research shows cows can be under heat stress from as low as 15C.

“I think the industry is recognising the impact of heat stress on animals and it’s a lot lower than people think. It’s not just when cows are panting that they are under heat stress, that’s when it’s really bad.”

The main issue they see with Slick animals is looking after young stock in the NZ winter.

“When they feel the cold they will grow hair to compensate, but it’s making sure in those first few weeks, calves born in a NZ winter, that you’re feeding calves warm milk.”

The Slick gene is dominant, so a homozygous bull will give all daughters one copy of the Slick gene.

“We’ve been milking Slick gene animals in NZ since 2010. Some of our cows have exceeded 10,000 litres and just under 1000kg milksolids (MS) in a season, this season we are confident we will break the 1000kg solids mark. Which just proves, these cows have plenty of milk ability. This Slick gene has nothing to do with damping down any other traits.”