Scientists Decode Genes Behind Holstein Cow’s Iconic Spots

Research led by Professor Matt Littlejohn at Te Kunenga ki Pūrehuroa Massey University has unveiled the genetic mechanisms responsible for the distinctive black and white coat patterns of Holstein-Friesian cows. This landmark study provides clarity on the genetic basis of traits that have been selectively bred since the early days of cattle domestication.

For centuries, coat patterns have been one of the most visible traits selected by farmers. While the genetic variations that create unique patterns in other breeds like Herefords and Galloways are known, the specific genes responsible for the Holstein’s iconic spots remained a mystery until now.

Using advanced genomic techniques, researchers analysed the coat patterns of thousands of cows. They identified two key DNA variants associated with two different genes: KIT and MITF. These genes are essential for pigmentation and have been studied in various species, including humans and dogs.

The discovery of the KIT gene variant in Holsteins is particularly intriguing. Unlike typical gene variants, this one does not reside within the gene itself but instead regulates it from a different location on the chromosome. Professor Littlejohn described it as akin to a “light switch turning on a light in another room,” illustrating the complexity of genetic regulation.

The MITF variant also exhibits unique properties, influencing the appearance of crossbred animals. This variant can produce unexpected coat patterns, such as black speckles in dairy cattle or the reversal of the traditional white face seen in Hereford crosses.

While these patterns may seem purely decorative, they hold significant implications for the dairy industry. Farmers often cross Holsteins with Herefords to produce calves that thrive in beef systems. The distinct white face is crucial for identifying these crosses. When calves exhibit irregular patterns due to the MITF variant, they can be harder to recognize, potentially reducing their market value.

Genetic testing may provide solutions for farmers seeking to produce calves with more predictable coat patterns. This research could also lead to improved animal welfare outcomes. Skin pigmentation plays a role in heat absorption and UV protection, which are vital for cattle comfort and performance. Understanding how these genes influence pigmentation can guide farmers in selecting optimal coat patterns for their herds.

“This research not only solves the mystery about how the Holstein gets its spots, but also shows how genes can interact to create unique and unexpected patterns,” said Professor Littlejohn. He emphasized that this work exemplifies how modern genomics can reveal the underlying mechanisms of traits that have been taken for granted for centuries.

The study, funded by the Ministry of Business, Innovation and Employment Endeavor Fund and the Livestock Improvement Corporation, contributes to a deeper understanding of cattle genetics, offering both practical applications and insights into the evolutionary history of livestock breeding.

The findings of this research are detailed in the paper titled “Structural and epistatic regulatory variants cause hallmark white spotting in cattle,” published recently. This work marks a significant step forward in the field of livestock genetics, bridging the gap between historical breeding practices and contemporary scientific understanding.