Written by Elliot Block, Ph.D., Research Fellow, Arm & Hammer Animal Nutrition
Milk fever is one of the most researched disorders in the history of animal health and dairy nutrition. That research has identified proven methods for controlling the onset of milk fever, and the nutrition protocols for transition cows based on that research has helped significantly reduce the incidence of milk fever over the past several decades.
We know how milk fever occurs. Blood calcium drops caused by the onset of lactation and rapid removal of calcium from the blood to support colostrum and milk production. This blood calcium drop can become severe enough to be classified as hypocalcemia, or milk fever.
If the blood calcium drop is not as severe, the animals may experience subclinical milk fever. These cows do not show clinical signs and may even appear normal; however, postpartum feed intake and production are not where they should be otherwise, and the cascade of postpartum diseases associated with low blood calcium will increase (metritis, retained placentas, dystocia, displaced abomasums, early culling, and ketosis).
We know how to prevent clinical and subclinical milk fever, and we’ve known it for decades. Feeding a diet to cows 21 days prior to the expected calving date that has a negative Dietary Cation-Anion Difference (nDCAD) creates an environment inside the cow that allows for bone calcium to mobilize when needed. This process reduces the incidence of clinical and subclinical milk fever and returns calcium to normal within 24 hours of calving. A review of meta-analytical data shows the results of feeding nDCAD prepartum as strong and significant reductions in total postpartum diseases per cow, including milk fever, metritis, and retained placentas, and a numerical reduction in displaced abomasums. Also, strong and significant increases in dry matter intake (DMI) and the subsequent postpartum milk yield (as volume, FCM and ECM) were shown (Santos et al., 2019; Lean et al., 2019; Lean et al., 2006; Oetzel, 1991).
Why change now? If we have a known enemy (milk fever), and decades of research show how to control it (nDCAD) with positive benefits to the cow, and an existing product that is proven to reduce transition disorders and stimulate DMI, why is it necessary to change our approach?
Some nutritionists have gone to feeding zeolites in transition diets as an easier option to prevent milk fever. While there is significantly more research on the effects of feeding a negative DCAD in transition diets, the limited research on zeolite does show that this method also reduces hypocalcemia at calving by limiting mineral absorption.
A specific synthetic zeolite has properties of strongly binding phosphorus, calcium and magnesium to a lesser extent, rendering these minerals less- to non-absorbable in the intestine. The resulting low blood phosphorus and magnesium forces bone mobilization to start within days of feeding zeolite and for the entire feeding period prepartum. Because bone mobilization is occurring well before calving, blood calcium does not decline along with blood phosphorous and magnesium. The superficial result is that hypocalcemia at calving is avoided.
Nutritionists have gravitated toward the use of zeolite products as an alternative to creating a negative DCAD environment because it’s a perceived easier way to achieve the same outcomes. But perception is not always reality.
First perception: With zeolites, I don’t need to monitor urine pH.
Reality: It’s true that by using zeolite, there’s no need to monitor urine pH. However, with nDCAD you only need infrequent monitoring to know that diets are being successfully formulated, mixed and fed. You might be trading the simplicity of a few urine pH samples for more extensive blood sampling at calving for minerals to know if you are feeding too little or too much zeolite. Further, if cows do go “down” at calving, you do not know if it is due to low phosphorus or low calcium.
Second perception: I’ll get the same benefits from zeolite as I will by achieving nDCAD.
Reality: The limited research on the real effects of zeolite shows either no effect or a slight negative effect on startup milk production. This could be due to research that shows DMI is negatively affected when feeding zeolite (Kerwin, et al., 2018; Grabherr et al., 2008; Frizarrini et al., 2024 a,b) at a time when we’re trying to get as much dry matter into the cow as possible to support early lactation health and production. Plus, the limited research on zeolite includes no long-term production results, and no report on reproduction, disease incidence, or culling rates.
Research also suggests that zeolite should not be fed for more than 21 days prepartum as the imposed phosphorus and magnesium deficiencies may have negative long-term effects (company website). Similarly, if zeolite is overfed, it can prevent the drop in calcium at calving that is needed to stimulate immunity and energy metabolism. Conversely, while there is no added benefit to feeding a nDCAD for more than 21-28 days prepartum, there is no detrimental effects either (Wu et al., 2014; Weich et al., 2013). Therefore, there is no concern if the expected calving date was not accurately estimated and cows remain on the nDCAD ration beyond 28 days.
Of concern, and with no supporting research, in feeding zeolite in transition is a risk of hypophosphatemia in the developing fetus in the weeks prepartum since blood phosphorous is documented to be very low. A phosphorus deficiency in cows can significantly affect their offspring by leading to poor fetal development, reduced birth weight, weaker bones, increased susceptibility to disease, and potentially impaired future growth and reproductive potential in the calves due to the vital role phosphorus plays in bone development and overall health during gestation (Grunberg 2020).
Third perception: With zeolites, I don’t need to reformulate rations as ingredients change.
Reality: If ration ingredients change enough to change DCAD levels, then they need reformulating to some extent regardless. You would also need to reformulate rations when using zeolite, you just don’t need to adjust for nDCAD level. Also, with zeolite, the ration would need to compensate for a reduction in DMI by 1 to 2 kg/d in addition to the dilution of ration nutrients as zeolite is a non-nutritive filler. According to the product literature phosphorus levels are required in order to feed the correct amount of zeolite and diets should be reformulated for protein and energy due to the dilution with zeolite and the reduced DMI.
While the perception may be that zeolites are easier to use, the reality is that the risks and uncertainties surrounding their use may be too much to overcome. Feeding ARM & HAMMER™ BIO-CHLOR™ to achieve a nDCAD diet is a system that has proven to work over decades of extensive, peer-reviewed research. Not to mention millions of cows who have successfully navigated calving and had productive lactations after being on a nDCAD diet in transition.
Set your transition cows up for success with BIO-CHLOR. Learn more at ahanimalnutrition.com or contact your local ARM & HAMMER representative.
