As more dairies adopt robotic milking systems (RMS), genetics play an even bigger role in making sure the right cows are entering the box. That is why STgenetics® developed the Robotic Cow Index (RCI) to help dairymen breed cows that are more efficient, healthier and better suited for robotic milking systems.
Piush Khanal, STgenetics® Quantitative Geneticist and Statistician, explains that the RCI is unique because it is the only genetic index built directly from robotic milking performance data, validated by millions of daily records worldwide. He says, “It helps identify females and bulls with superior genetics for robotic milking efficiency.”
RCI at a Glance
RCI values the traits that matter most in a robotic milking system.
“Currently, RCI includes seven different traits,” Khanal shares. “These include conformation traits, milking speed-related traits and health-related traits, like mastitis.”
As nearly half of the index is devoted to milking speed and box time, key factors in robot efficiency, it is important to understand the differences between these traits. They are also published as standalone traits, alongside effective milking speed. Here is how these important traits differ:
Milking Speed is total pounds of milk per minute of milking time.
Box Time is total time spent in robot between entrance and exit, including identification, preparation time, milking time, etc.
Effective Milking Speed is total pounds of milk per minute of box time.
Conformation traits, such as teat placement and teat length, are also built into the index since udder structure directly affects attachment and scan time.
CDCB Milking Speed VS. STgenetics® RCI
While CDCB now publishes milking speed as a standalone trait as of August 2025 proofs, STgenetics® RCI provides a more complete picture.
The August 2025 Genetic Evaluation showed heritability of 0.42 for CDCB Milking Speed versus the 0.52 of RCI, meaning faster progress can be made through selection with RCI. RCI also includes mastitis resistance and somatic cell score, recognizing the link between milking speed, milk yield, and udder health. “We want cows to milk out cleanly and efficiently,” notes STgenetics® Director of Genetic Development David Kendall, “but we also don’t want to invite mastitis or high somatic cell counts.”
Another key difference is in the data source. CDCB relies on non-robotic sensors, while RCI is powered by robotic sensor data collected directly from automatic milking systems. With over 1.8 million daily phenotype records from herds in the U.S., U.K., France, and Australia, RCI continues to expand and improve.
The Bottom Line
STgenetics® Robotic Cow Index (RCI) combines milking speed, box time, udder conformation, and health traits into one powerful index. For producers, that means cows that are not only productive and efficient in the robot, but also healthier, more profitable, and built for the future.
Hear more about RCI using the links below:
Spotify: https://bit.ly/4m7oHbA
Apple: https://bit.ly/45I7dNa