Fluctuations in milk yield measured by milking robots can be used to breed cows that can cope well with problems, and cows with fewer fluctuations are healthier, more resilient and live longer, according to researchers at Wageningen University & Research (WUR) in the Netherlands.
Researchers at WUR and CRV, which trades in genetic material (such as semen from a breeding bull), discovered that there are genetic differences among cows in the variability of their milk yield. This discovery 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,” Wageningen Livestock Research scientist Marieke Poppe said. “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 fewer fluctuations in milk yield, Poppe said, adding, “Daily milk yield records could, thus, help to breed cows that can handle problems better -- cows that are more resilient.”
The researchers explained that fluctuations in milk yield provide information 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,” the researchers said.
Until recently, only milk yield records taken every three to six weeks were available for genetic analysis, so it was not possible to study variation in milk yield from day to day.
“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',” researcher Han Mulder noted.
According to WUR, further research will focus on the additional value of this new trait compared to existing traits currently used in breeding, such as for udder health and longevity. The additional value may be that this trait better shows how much cows react to stressors and how quickly they recover, WUR said.
If there is, indeed, an additional value, breeding values for fluctuations in milk yield can be estimated, which would allow farmers to breed trouble-free cows even better in the future.