Scientists Unravel Genetic Secrets Behind Holstein Cattle Spots

Researchers have successfully identified the genetic basis behind the distinctive black-and-white coat patterns of Holstein cattle, a trait emblematic of dairy farming worldwide. A study led by Professor Matt Littlejohn from Te Kunenga ki Pūrehuroa Massey University reveals that two specific DNA variants are responsible for the unique spotting patterns seen in these cows.

Historically, coat patterns have been among the earliest traits selected by farmers, reflecting the long-standing influence of human cultivation on domestic cattle populations. While the genetic determinants for patterns in other breeds, such as the white face of Herefords or the belts of Galloways, have been documented, the mystery surrounding Holstein spots had persisted until now.

Using advanced genomic techniques, the research team analyzed the coat patterns of thousands of Holsteins. They identified two critical genes, KIT and MITF, that account for much of the variability in Holstein spotting. Professor Littlejohn explains, “These genes are well-known for controlling pigmentation in humans, mice, dogs, horses, birds, and other species.”

The KIT gene variant discovered in Holsteins is particularly intriguing; it does not reside within the gene itself but regulates it from a separate location on the chromosome. “Think of it like a light switch turning on a light in another room,” Littlejohn comments. The MITF variant also stands out for its ability to create unique patterns when different breeds are crossed. This can lead to striking features such as black speckles in dairy crosses or unexpected coloration in Hereford crosses.

The implications of this research extend beyond aesthetics. Many dairy farmers breed Holsteins with Herefords to produce calves that perform well in beef systems. The white face is crucial for identifying these calves as Hereford crosses. When calves with irregular facial patterns emerge due to the MITF variant, they can be harder to recognize and subsequently less valuable. Professor Littlejohn emphasizes that genetic testing could help ensure more predictable coat patterns in future calves.

Potential Benefits for Cattle Welfare

Beyond the economic aspects, this study may also enhance animal welfare. Skin pigmentation has significant effects on heat absorption and UV protection. Black coats, for instance, absorb more heat but also offer better protection from ultraviolet rays. Understanding how these genes influence pigmentation could assist farmers in selecting coat patterns that optimize cattle comfort and performance.

“This research not only solves the mystery about how the Holstein gets its spots but also illustrates how genes can interact to create unique and unexpected patterns,” Littlejohn notes. He adds that early animal breeders likely favored spotted animals centuries ago, and now, the molecular basis for these preferences is clearer than ever.

The research received funding from the Ministry of Business, Innovation and Employment Endeavor Fund and the Livestock Improvement Corporation. The findings were published in the paper titled, “Structural and epistatic regulatory variants cause hallmark white spotting in cattle,” contributing valuable insights to the field of animal genetics and breeding practices.