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In a recent study done at the University of Wisconsin-Madison by Frizzarini et al. (2024)*, researchers compared three close-up diets and their implications on blood calcium and performance. The three diets included one diet with X-Zelit, one diet with negative dietary cation-anion difference (-DCAD) and one with a positive DCAD (control). The study, which resulted in two publications published in the Journal of Dairy Science, showed that cows fed the diet with X-Zelit had higher blood calcium concentrations and lower blood phosphorus concentrations during the transition period relative to the other treatments. In addition, cows fed X-Zelit had higher colostral IgG concentrations, plus cows in their third or greater lactation fed X-Zelit produced the most milk.

X-Zelit is a dietary phosphorus binder that naturally stimulates a cow to mobilize her own calcium reserves for effective milk fever prevention. This novel approach capitalizes on manipulating phosphorus homeostasis, rather than calcium homeostasis. X-Zelit is recommended to be fed 14 to 21 days pre-fresh to prevent milk fever and subclinical hypocalcemia.

“Despite the vast improvements made in the industry to manage milk fever, subclinical hypocalcemia and “milk fever breaks” still remain a challenge on dairy operations. This challenge has resulted in continuing research of pre-fresh nutrition strategies to mitigate clinical and subclinical hypocalcemia,” says Dr. Meghan Connelly, Protekta dairy research and technical services.

The University of Wisconsin study included 121 multiparous Holstein cows, blocked by lactation number and expected due date. Cows were randomly assigned to one of the three prepartum diets: control (+190 mEq/kg; n = 40), -DCAD (−65 mEq/kg; n = 41), or the control diet supplemented with X-Zelit (synthetic zeolite A; +278 mEq/kg, fed at 3.3% DM, 500 g/day; n = 40).

In Part 1 of the study, researchers evaluated the effects of the three diets on peri-partal mineral metabolism. Some of the mineral metabolism metrics Dr. Frizzarini and colleagues analyzed were blood calcium, blood phosphorus and fecal phosphorus. The results showed that cows fed X-Zelit exhibited the highest blood calcium concentrations pre-partum and during the first few days following calving relative to cows fed -DCAD or control diets.

Also, cows fed the diet with X-Zelit had lower blood phosphorus concentrations relative to all other treatments, which is consistent with previously published research results. In addition, these cows had decreased salivary phosphorus concentrations and increased fecal water extractable phosphate, collectively suggesting that feeding X-Zelit induces a mild hypophosphatemia.

In Part 2, the research team assessed the effects of feeding the same three close-up diets (X-Zelit, -DCAD and the control diet) on dry matter intake (DMI), energy metabolism, and colostrum and milk production. In this companion paper, researchers measured daily prepartum DMI, daily rumination, colostrum quality and quantity, daily milk production and supplemental blood work to evaluate energy metabolism.

The results showed that feeding a diet with X-Zelit reduced DMI and rumination pre-partum compared to -DCAD and control diets, but no differences were observed in rumination postpartum. Despite the pre-partum decrease in DMI and rumination in X-Zelit fed cows, blood glucose, β-hydroxybutyrate (BHB) concentrations, and body fat mobilization postpartum were not different between treatments.

After analyzing colostrum samples, researchers determined that yield and BRIX score did not differ between dietary treatments; however, colostrum collected from cows fed X-Zelit had the highest IgG concentrations (91.10 ± 2.63 mg/mL for X-Zelit, 78.00 for control, and 78.90 for -DCAD). Results also showed that mature cows (third or greater lactation) fed X-Zelit had the highest milk production (51.0 ± 1.1 kg) during the first 49 days in milk compared to cows fed -DCAD or control diets.

“Overall, these results support that the improvement in blood calcium concentrations pre and postpartum from feeding X-Zelit is most likely regulated by a dietary phosphorus restriction,” said Dr. Connelly. “This research helps further validate the role that dietary phosphorus plays in hypocalcemia and corroborates the results nutritionists and producers are seeing on farm. X-Zelit poses an intriguing option for close-up cows as this mechanism appears to be independent of DCAD, which means the need to source low potassium forages is reduced. Consequently, the pre-fresh diet has a lot more forage flexibility and you can include home grown forages higher in potassium.”

Protekta is dedicated to advancing animal well-being with a focus on scalable solutions and environmental sustainability. Our commitment drives our innovative product portfolio, designed to enhance the overall health of animals. Discover more about Protekta and our flagship product, X-Zelit, at Protekta.com.

J Dairy Sci. (March 13, 2024) Mechanisms by which feeding synthetic zeolite A and a dietary cation-anion difference diets impact mineral metabolism in multiparous Holstein cows: Part 1 https://www.journalofdairyscience.org/article/S0022-0302(24)00546-0/fulltext

J Dairy Sci. (March 13, 2024) Mechanisms by which feeding synthetic zeolite A and a dietary cation-anion difference diets impact feed intake, energy metabolism and milk performance: Part 2https://www.journalofdairyscience.org/article/S0022-0302(24)00547-2/fulltext