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Table 2. The effect of feeding synthetic zeolite for three weeks pre-calving on milk production (at ~6 weeks in milk), relative to untreated controls. Variable Control Zeolite P-value Milk volume (L/cow/day) Milksolids (kg/cow/day) Milk fat % Milk fat (kg/cow/day) Milk protein % Milk protein (kg/cow/day) Fat to protein ratio 27.8 27.3 * 2.20 2.16 * 4.34 4.31 NS 1.20 1.17 ** 3.64 3.65 + 1.01 0.99 + 1.20 1.18 * Statistically significant differences between control and zeolite groups are indicated at * (P<0.05) and ** (P<0.01), whereas a trend is indicated at + (P<0.10), and NS indicates non-significance at P>0.10. Similarly, we did not determine any difference in uterine health, measured by Metricheck scoring at one month after calving. We also saw no differences in cases of clinical mastitis between calving and mating start date. However, the incidence of cows with somatic cell counts greater than 200,000 cells/ml at the first herd test (about six weeks in milk) was lower in the zeolite-treated cows than in untreated controls: 10% vs 14%. Hence, there may be some benefits to mammary health and milk quality. Feeding zeolite pre-calving resulted in small (less than 2%) but statistically significant reductions in milk volume and milksolids yields, measured at the first herd test after calving ( Table 2 ). These effects may be related to suppressed dry matter intake pre-calving, as reported in some overseas studies. Nevertheless, evidence from both small- and large- scale studies indicates these effects are relatively subtle and most likely outweighed by the benefits of reduced subclinical and clinical milk fever. Trial cows eating maize silage supplemented with synthetic zeolite. Inside Dairy | April / May 2022 25
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Frequently Asked Questions 1. Should I use magnesium supplements with synthetic zeolite? 5. Does natural zeolite, mined from clay deposits, have the same effect as synthetic zeolite? It’s important to use an optimal magnesium supplementation strategy starting at the same time pre-calving. Preferably, more than one method of magnesium supplementation should be used. 2. How does feeding synthetic zeolite pre-calving compare with reducing DCAD (dietary cation:anion difference)? A negative DCAD pre-calving has been demonstrated to prevent milk fever in housed cows, but this can be difficult to achieve in grazing cows due to the high potassium content of pasture. Using synthetic zeolite is an alternative to a negative DCAD strategy, which requires adding large amounts of anionic salts of chloride and sulphate to the diet and feeding low- potassium feeds, such as maize silage. 3. When do I stop feeding synthetic zeolite? Zeolite supplementation should stop immediately after a cow calves, so that she can absorb dietary calcium. 4. Is synthetic zeolite compatible with low-phosphorus diets, such as fodder beet? This hasn’t been tested yet, so it is not recommended to feed synthetic zeolite when cows are on fodder beet or other low- phosphorus diets. Synthetic zeolite is produced from natural zeolites to have a standardised composition. However, different types of zeolite have different mineral-binding properties in the cow’s gut, which alters their effects on the animal. Only synthetic zeolite is scientifically proven to reduce the risk of subclinical and clinical milk fever under a range of farm systems. The safety and efficacy of feeding natural zeolites pre-calving to reduce milk fever are unknown and, therefore, this is not recommended. 6. What is the palatability of synthetic zeolite? Both DairyNZ and overseas experiments indicate that targeting a dose of 500g/cow/d is optimal – offering higher dose rates can reduce palatability and may limit feed intake. Mixing synthetic zeolite into supplementary feeds such as maize silage, or incorporating into pelletised feed rather than top-dressing onto feeds, can improve palatability, if required. Acknowledgements This research was conducted under the Pillars of a New Dairy System research programme, funded by New Zealand dairy farmers through the DairyNZ levy, and by the Ministry for Business, Innovation and Employment. We thank the farmers and their staff whose herds were enrolled in our Zeolite Scale- Up Trial. References 1 Roche, J. R. 2003. The incidence and control of hypocalcaemia in pasture-based systems. Acta Veterinaria Scandinavica Supplementum 97:141-144. 2 Roberts, K. I., and S. McDougall. 2019. Risk factors for subclinical hypocalcaemia, and associations between subclinical hypocalcaemia and reproductive performance, in pasture-based dairy herds in New Zealand. New Zealand Veterinary Journal 67:12-19. doi: 10.1080/00480169.2018.1527732. 3 Thilsing-Hansen, T., and R. J. Jørgensen. 2001. Hot topic: Prevention of parturient paresis and subclinical hypocalcemia in dairy cows by zeolite A administration in the dry period. Journal of Dairy Science 84:691-693. doi: 10.3168/jds.S0022-0302(01)74523-7. 4 Kerwin, A. L., C. M. Ryan, B. M. Leno, M. Jakobsen, P. Theilgaard, D. M. Barbano, and T. R. Overton. 2019. Effects of feeding synthetic zeolite A during the prepartum period on serum mineral concentration, oxidant status, and performance of multiparous Holstein cows. Journal of Dairy Science 102:5191-5207. doi:10.3168/jds.2019-16272. 5 Crookenden, M. A., C. V. C. Phyn, S. A. Turner, J. J. Loor, A. I. Smith, V. Lopreiato, C. R. Burke, A. Heiser, and J. R. Roche. 2020. Feeding synthetic zeolite to transition dairy cows alters neutrophil gene expression. Journal of Dairy Science 103:723-736. doi:10.3168/jds.2019-17097. 26 Inside Dairy | April / May 2022
