Hypocalcemia: A new solution for an age-old problem

Hypocalcemia, commonly referred to as milk fever, has plagued the dairy industry for years.  During his breakout presentation at Vita Plus Dairy Summit 2019, Dr. Zach Sawall, Vita Plus nutritionist, described a new strategy that’s proven an effective weapon against this age-old problem.

Sawall said hypocalcemia in lactating dairy cows is defined as blood calcium levels below 8.5 mg/dL.  Hypocalcemia results in lower immune function, depressed dry matter intakes, poor body condition, and reduced muscle function, including uterus and gastrointestinal tract function. 

In turn, this will likely trigger fresh cow challenges such as dystocia, ketosis, displaced abomasums, retained placentas, metritis and mastitis.  Over time, hypocalcemia can negatively impact a herd’s production, reproductive efficiency, productive life and overall profitability.

Sawall described how hypocalcemia strategies have evolved throughout the decades:  low-calcium prefresh diets in the ‘70s and ‘80s, low-potassium diets in the ‘90s, and DCAD diets since the turn of the century.  These strategies share a common goal of “turning on” the parathyroid hormone and signaling the mobilization of bone calcium. 

As we approach 2020, a product relatively new to the U.S. marketplace may be even more effective – and easier to use on some dairies – as producers work to limit hypocalcemia challenges.  X-Zelit®, a product of Protekta, binds dietary calcium and phosphorus.

It is fed for about 14 days prefresh.  When fed X-Zelit, the parathyroid hormone signals for bone calcium mobilization because dietary calcium is bound to X-Zelit and, thus, unavailable to the cow.  One major benefit is that producers have more flexibility in forage selection because they don’t need to source low-potassium feeds.

As Sawall and other nutritionists have successfully added X-Zelit to close-up prefresh diets, he said one major finding is that binding both calcium and phosphorus is key to increasing post-calving blood calcium levels.  However, this isn’t necessarily a new concept.  Sawall cited several published studies that showed low precalving dietary phosphorus levels led to increased postpartum blood calcium.

Sawall pointed out that X-Zelit is not a fit for all farms.  X-Zelit’s physical properties require the bagged product to be added to the TMR on farm.  It also doesn’t work with diets that are too dry (less than 50% moisture) because the product won’t dissolve and cows will sort it.  Perhaps the biggest limitation is not having a close-up group as Sawall does not recommend feeding X-Zelit for more than 21 days precalving.

That said, Sawall highlighted several “optimal” situations for feeding X-Zelit:

• Farms that can accommodate a 14-day prefresh group
• Farms that want to feed homegrown forages and avoid purchasing straw or other low-potassium forages
• Farms that struggle with down/lethargic cows due to hypocalcemia
• Farms that struggle to manage a DCAD program

The biggest benefit Sawall has observed is fewer cow touches.  X-Zelit virtually eliminates the need for calcium boluses and/or calcium IVs, saving the farm money in terms of treatment costs.  It also reduces stress on the animals and labor needs for treating fresh cows.