Scientists Decode Genes Behind Holstein Cows’ Distinctive Spots

Research has revealed the genetic basis for the iconic black-and-white coat of Holstein cows, a breed synonymous with dairy farming worldwide. A team led by Professor Matt Littlejohn from Te Kunenga ki Pūrehuroa Massey University has identified two specific DNA variants, linked to the KIT and MITF genes, which are responsible for the distinct spotting patterns of these animals.

The study utilized advanced genomic techniques to analyse the coat patterns of thousands of Holsteins. Until now, the genetic underpinnings of their distinctive patterns remained a mystery, despite other cattle breeds having their DNA variants identified. This breakthrough sheds light on a trait that has been shaped by farmers for centuries, highlighting the long-standing relationship between agriculture and animal genetics.

Uncovering Genetic Mechanisms

Both the KIT and MITF gene variants play crucial roles in determining pigmentation. According to Littlejohn, the KIT gene variant is particularly interesting because it does not reside within the gene itself; rather, it regulates the gene from a different location on the chromosome. “Think of it like a light switch turning on a light in another room,” he explains.

The MITF variant has implications that extend beyond aesthetic appeal. It influences how different breeds interact genetically, resulting in unique coat patterns. For example, it can produce black speckles in crossbred dairy cattle or create unexpected variations, such as a reversal of the typical white face seen in Hereford crosses.

While these patterns may seem decorative, they hold significant agricultural value. Many dairy farmers cross Holsteins with Herefords to produce calves that excel in beef production. The traditional white face is a marker indicating a Hereford cross, and when calves exhibit irregular patterns due to the MITF variant, they may not be easily identified as such, potentially impacting their market value.

Implications for Animal Welfare and Farming Practices

The research also has practical applications related to animal welfare. Skin pigmentation affects both heat absorption and UV protection for cattle. Black coats, while absorbing more heat, provide enhanced UV protection. Understanding the genetic control of pigmentation can guide farmers in selecting traits that enhance cattle comfort and overall performance.

“This research not only solves the mystery about how the Holstein gets its spots but also demonstrates how genes interact to create unique and unexpected patterns,” Littlejohn says. He notes that early animal breeders likely selected spotted animals hundreds or even thousands of years ago, and this study reveals the molecular basis behind those choices.

The findings were supported by funding from the Ministry of Business, Innovation and Employment Endeavor Fund and the Livestock Improvement Corporation. The comprehensive results are published in the paper titled “Structural and epistatic regulatory variants cause hallmark white spotting in cattle,” providing valuable insights for both the scientific community and farmers alike.