A Kiwi company says it has bred the world's first team of bulls that all carry a dominant gene certain to breed heat-tolerant cows.
Thermo Regulatory Genetics has bred a team of four homozygous Jersey bulls who all have the "Slick" gene, named because cattle who inherit the gene have very short hair and appear shiny and wet.
Their lack of hair kept them up to 1°C cooler than other cattle and was enough to make them perform significantly better in hot and humid temperatures.
This made them ideal for dairy operations in tropical countries.
"Homozygous" meant all daughters born to the bulls were guaranteed to have the Slick gene.
Chief executive Derek Fairweather said these world-first genetics were one part of a complex puzzle that could help provide greater food security, particularly protein security, in some of the globe's hottest and poorest populations.
"We started in 2008 breeding Slick genetics into dairy cows, after our team had done a fair amount of travel around the tropics. In these regions we saw a lot of very average cows, providing very average returns for local farmers.
"We came away from those trips wanting to develop better genetics for the tropics because we understood that the added financial returns gained from better-producing cows could literally mean the difference for a farmer sending his child to school or not."
As climate change took hold, many popular breeds used in the tropics produced less as temperatures rose, Fairweather said.
The company's research found Jerseys performed better in high temperatures.
"So, we've selected top Jersey bulls, introduced the Slick gene and now have the world's first team of four homozygous bulls."
Thermo Regulatory Genetics signed a strategic alliance with the University of Florida, led by Dr Pete Hansen, with the University team leading research in the space of heat tolerant genetics.
"Our research on Holsteins with the Slick gene has shown cows with the gene don't suffer the drop in milk yield during heat stress that other cows do," Hansen said.
"We've also found that Slick cows have lower body temperatures in hot conditions, and our colleagues in Puerto Rico have shown that calving intervals are around two months shorter than non-Slick cows."
Fairweather said the company was now going back to farmers in the tropics to gather data from cows bred there over the last five years, to continue to improve and refine the genetics by applying traditional breeding methodology.
This included the use of genomic testing to assess genetic potential, and selecting the most economically important traits for milk producers.
"We are a science and data driven company so it's not about promoting one breed. We're continuing to gather data so we can understand which daughters of the bulls are really performing so we can build a proven superior animal, specifically for the tropics."
He said the company was also breeding polled genetics (cattle that don't grow horns) to reduce the risk of infection from dehorning in humid environments and cows that specifically produce A2 milk, for countries like Pakistan only A2 genetics are allowed to be imported.
The next frontier would be adding traits, such as resistance to ticks.
"There's 250 million dairy cows in the tropics so there is real potential and opportunity in developing the right cow for that climate."
Fairweather emphasised that this was all achieved through a natural breeding programme.
"We are and will not pursue gene editing, as that triggers complex and unnecessary issues."