Fluctuations in milk yield measured by milking robots can be used to breed cows that can cope better with health problems, researchers say.
Scientists in the Netherlands have discovered that there are genetic differences between cows in the variability of their milk yield.
This discovery, made by scientists at Wageningen University & Research and genetics firm CRV, was done based on daily milk yield records of almost 200,000 cows.
“The milk yield of some cows fluctuates much from day to day, whereas the milk yield of other cows remains stable,” said researcher Marieke Poppe at Wageningen Livestock Research.
“We noticed that cows with a genetic merit for stable milk yield often had a genetic merit for good udder health and few metabolic problems, such as ketosis.
“Cows with a stable milk yield also tended to live longer.”
Because there are genetic differences between cows, it is possible to breed for less fluctuations in milk yield, he explained.
Poppe added: “Daily milk yield records could thus help to breed cows that can handle problems better; cows that are more resilient.”
The researcher explains why fluctuations in milk yield are informative about the ability of cows to handle problems.
“When a cow has to deal with a disease or other complication, her milk yield will drop temporarily.
“This is comparable to humans: when we are ill, we also take it easy for a while. Such short term drops in milk yield lead to fluctuations in milk yield, which you will see less in cows that can handle stressors well,” he said.
Until recently, only milk yield records that were taken every 3-6 weeks were available for genetic analysis.
Therefore, it was not possible to study variation in milk yield from day to day.
Researcher Han Mulder said: “Now that daily milk records from milking robots are available, we have the unique opportunity to study short-term fluctuations in milk yield as an indicator of “trouble-free cows”.
Further research will focus on the additional value of this new trait compared to existing traits currently used in breeding, such as udder health and longevity.
The additional value may be that this trait grasps better how much cows react to stressors and how quickly they recover.
If there is indeed an additional value, breeding values for fluctuations in milk yield can be estimated.
This would allow farmers in the future to breed trouble-free cows even better.
