Researchers propose a change in the approach to the treatment of dairy cows

For dairy cows, the transition period, that is, the time between the birth of a calf and the start of milk production, creates the greatest likelihood of health problems. It is now widely believed that the effects of an excess of non-esterified fatty acids (NEFA) in the circulation and subsequent hyperketonemia during this period, combined with low levels of available calcium, are the most common causes of disorders such as mastitis, metritis, retained placenta, and poor fertility.

For a long time, much attention was paid to the regulation of NEFA and calcium levels in cows. However, these measures did not bring the expected effect. Meanwhile, approximately 75% of diseases occur in the first months after childbirth. As a result, dairy producers literally pay for this with a decrease in milk production, treatment costs, early culling of cows, and a decrease in reproductive abilities.

In a new review in the journal Dairy Science, a team of scientists from the Department of Zoology at Iowa State University, Ames, Iowa, USA , led by Lance H. Baumgard, Norman L. Jacobson, Professor of Dairy Nutrition, takes a critical look at the current generally accepted understanding of cow health in a transitional period to investigate the causes of these persistent problems. Their findings call into question the methods and findings of a large body of previous research and how such work has been applied to dairy farming.

"Over the past 50 years, elevated circulating NEFA and ketones and hypocalcemia have been generally viewed as pathological and detrimental," Baumgard noted.

The research team found that this principle is largely based on observational studies, epidemiology, correlations, and ex vivo analyzes of immune cell functions.

“It is becoming increasingly clear that comorbidities cannot be explained by the severity of changes in simple metabolites. The interpretation of biomarkers as the cause of metabolic disorders is not consistent with the purpose of epidemiological studies,” Baumgard added.

In their review of previous research, Baumgard and colleagues emphasized the fundamental scientific principle that "correlation does not equal causation."

The team of researchers concluded that post-calorie changes in energy and calcium metabolism reflect normal biological processes. Healthy animals use these processes to maximize milk production. In other words, conditions that have been widely seen as indicative of ill health may in fact represent normal and even benign features - and some of the ways in which the transition is handled may actually exacerbate the problems. Unhealthy cows, such as those with mastitis, use similar processes to maintain an effective immune system. Thus, an unhealthy cow and a high producing healthy cow have similar metabolic profiles.

Baumgard and colleagues lay the groundwork for exploring this perspective further, suggesting that future research could focus on preventing immune system activation in cows, thereby reducing the negative effects of inflammation. Thus, by paying close attention to scientific rigor, they hope to make progress in overcoming transitional cow health issues that remain key barriers to profitable dairy farming and overall agricultural sustainability.