The transition period is the most critical point in a dairy cow’s production cycle. At this time, a cow relies most heavily on her immune system to maintain health and productivity.
The transition period is typically defined as the last three weeks leading up to calving and the first three weeks of lactation. During this period, normal physiological demands for preparation of calving – combined with the sudden demand for production of large volumes of milk – interface with some of the most stress-related management practices imposed on the cow.
Natural and management-imposed factors may compound each other, ultimately challenging the cow’s natural defense mechanism for maintaining health. How cows are fed and managed during this fragile transition period will ultimately determine their health status and milk yield potential.
There are many aspects related to the periparturient dairy cow’s immune dysfunction. Proper management and nutrition can play a role in overcoming transition cow health challenges by:
• addressing factors that negatively affect immune function;
• implementing management and feeding strategies to reduce prepartum stress and reduce immune dysfunction;
• managing feeding practices that enhance prepartum feed intake;
• manipulating dietary nutrients to reduce immune dysfunction; and
• using diagnostic tools that can be used to monitor transition cow performance.
It has been known for many years that the cow’s susceptibility to both metabolic and infectious disease is greatest during the first three to six weeks of lactation. Evidence of this link became more apparent during the early 1980s, when several research groups began to focus on transition cow physiology and the relationships linking immune dysfunction with management and nutritional practices.
Work from Cornell University’s School of Veterinary Medi- cine in 1985 reported on the direct and indirect relationships among periparturient diseases occurring within the first 30 days of lactation to the dietary nutrient intake during the last three weeks of gestation. Specifically, they reported reduced incidence of metabolic and reproductive disorders when cows were fed nutrient levels (protein and energy during the last three weeks prior to calving) greater than those recommended by the National Research Council.
A few years later, collaborative research in 1989 conducted between groups at the National Animal Disease Center and the Department of Veterinary Medicine in Ames, Iowa, reported that lymphocytes (white blood cells which are part of the adaptive immune system and associated with antibody production and function) are significantly impaired particularly during the first week following calving.
While the direct cause-and-effect relationship between management and nutritional practices with metabolic disease of the early lactating dairy cow are still not clearly understood, several key management and nutritional strategies can be implemented to reduce the effects of immune dysfunction around the time of calving and into early lactation.
Ken Zanzalari, Ph.D., Dipl. ACAN is an ARPAS board-certified nutritionist with Prince Agri Products, Inc. specializing in transition cow management and nutrition.