Risk of Low Blood Calcium With Transition Cows
Joining us today on DairyLine Radio is Dr. Angie Rowson, research and technical support veterinarian with Phibro Animal Health.
DairyLine: Dr. Rowson, let’s begin by discussing the risks of low blood calcium and impaired immune function that dairy cows can experience during transition.
Angie Rowson: Around the time of calving, dairy cows can become immunosuppressed, making them more susceptible to diseases such as mastitis, metritis and retained placental membranes.
The exact causes of weakened immune function are unknown, but may be linked to changes in their endocrine, or hormonal system, nutritional deficiencies and metabolic factors.
Research has also demonstrated that low blood calcium, or hypocalcemia, during the transition period can have a negative impact on immune function, since calcium is critical for effective immune-cell activation and function.
DairyLine: A negative DCAD diet is often recommended as a way to reduce the risk of low blood calcium. Can you explain how it works?
Angie Rowson: Sure, Feeding a negative dietary cation-anion difference, or DCAD, diet is one of the most researched and effective prepartum feed strategies to prevent milk fever and subclinical hypocalcemia.
Around the time of parturition, dairy cows face high calcium requirements for colostrum and milk synthesis.
A pre-fresh diet with a higher concentration of anions (primarily chloride and sulfur) compared to cations (primarily potassium and sodium) allows the animal to compensate for calcium losses, preventing or reducing clinical and subclinical hypocalcemia.
DairyLIne: How do Phibro’s nutritional specialty products, Animate® and OmniGen-AF®, address health issues relating to low calcium and suppressed immune function?
Angie Rowson: When fed as part of a properly balanced, negative DCAD prepartum diet, Animate has been proven to help reduce the incidence of both clinical and subclinical hypocalcemia. And, because it is highly palatable, it can be used to fully acidify the pre-fresh diet without fear of lower dry matter intake.
OmniGen-AF is recommended to be fed to all dry, pre-fresh and lactating cows to help support normal immune function in the face of expected and unexpected stress. Research has demonstrated that continual use may help result in fewer health events, a lower somatic cell count and fewer cases of diseases and infections, such as mastitis and metritis. This, in turn, may lead to higher milk production and fewer unplanned culls.
DairyLine: Dr. Rowson, what are your recommendations for feeding a negative DCAD diet prepartum?
Angie Rowson: Negative DCAD diets are typically fed for 21 days prior to calving prior to partuition. However, recent research has demonstrated they can be fed six weeks prepartum without negatively affecting cow health or performance.
Producers should ensure that proper dietary concentrations and amounts of macrominerals are included in the pre-fresh diet.
Additionally, Urine pH values of pre-fresh cows should be measured regularly. This is a quick and inexpensive way to gauge the effectiveness of the negative DCAD diet. The recommended pH range is between 5.5 and 6.0 for fully-acidified diets.
It is also important to determine the incidence of subclinical hypocalcemia through blood calcium testing. The traditional threshold has been 8.0 mg/dL, but recent research suggests a target threshold of 8.5 mg/dL.
Finally, identify and correct any management or environmental factors that might cause stress and further compromise immune function during transition. It’s important to provide adequate bunk space in the pre-fresh group, minimize pen moves and group changes near calving dates, ensure optimal freestall size, cushion and cleanliness, and mitigate heat stress.