Feeding Trials Magnesium Sulfate versus Magnesium Oxide
In collaboration with the Faculty of Agricultural Sciences at Osnabrück University of Applied Sciences, we examined the influence of using magnesium sulfate instead of magnesium oxide on the health and growth of piglets.
Feeding trials were conducted in a 8,000-piglet rearing barn in Rheine an der Ems. This family-owned business has been involved in animal husbandry for five generations and regularly conducts practical trials with the university to optimize pig farming. Several feeding trials with anhydrous magnesium sulfate (KaSa Mag98) have already been conducted there.
Magnesium in Piglet Rearing
At the beginning of piglet rearing, weaning from the sow, relocation, a change in feed, and forming new groups can lead to a general state of stress in the piglets. Adequate mineral supply ensures good physical development and positively influences well-being in both humans and animals.
Magnesium oxide (MgO) is commonly used in piglet rearing due to its market availability, affordability, and apparent magnesium content. Many livestock farmers are deterred by the higher price of alternative magnesium sources, even though they may have better bioavailability.
The piglets were divided into groups for the trials. One group received the standard piglet feed containing magnesium oxide, while the other group received the same amount of anhydrous magnesium sulfate. The dosage was 0.75 kg/t in the first trial and 0.5 kg/t in the second. A zero variant without magnesium supplementation was also included in the second trial run. Throughout the trials, we documented feed intake, body weight, medication administration, injuries, and stool consistency. Stress levels were measured based on cortisol concentration in the animals' saliva. Cortisol, a steroid hormone, is an important messenger substance for stress reactions in the body. In dangerous situations, cortisol provides energy and supports the fight-or-flight response. To ensure stress-free sampling, a cotton rope was hung in each pen for 30 minutes. The piglets chewed on the rope and left saliva samples.
Magnesium Sulfate Increases IOFC
Adding magnesium sulfate instead of magnesium oxide at the beginning of piglet rearing reduces stress and ensures a higher body weight. Despite the higher product price, the improved feed efficiency results in a higher income over feed cost (IOFC).
Compared to magnesium oxide, the addition of magnesium sulfate resulted in:
- Generally lower cortisol levels
- Significantly higher daily weight gains
- Numerically reduced medication use
- Economic advantages (higher IOFC)
The magnesium in our product is fully water-soluble, making it completely available to the animal. In contrast, only around 10% of the magnesium dose from magnesium oxide is available, depending on the species of animal, and most of it is excreted.
Greater Weight Gain
Throughout the entire piglet rearing period, animals in the magnesium sulfate group gained more live weight than those in the magnesium oxide group. Feed conversion tends to be better with magnesium sulfate.
Piglets that were fed magnesium sulfate had higher live weights and were more efficient feeders than those that were fed magnesium oxide or no magnesium supplements.
Less Stress and Fewer Medications
In contrast to the magnesium oxide group, the cortisol concentration in saliva decreased continuously over the course of the study. Therefore, the magnesium sulfate group was better able to reduce stress.
The control and magnesium oxide groups administered medication more than twice as frequently as the magnesium sulfate group. This resulted in lower treatment costs of 10 cents per piglet.
Piglets that were fed magnesium sulfate experienced less stress, as evidenced by their lowest cortisol levels in saliva, compared to animals that were fed magnesium oxide or no magnesium supplementation.
Compared to animals fed magnesium oxide or no magnesium supplementation, piglets fed magnesium sulfate required less than half the amount of medication.
Higher Profitability
The economic efficiency calculation (IOFC), which included treatment costs, revealed that the KaSa Mag98 variant was 52 cents more economical per animal than magnesium oxide. The negative control without magnesium supplementation was even more economical, at around 20 cents per piglet, than the control variant with magnesium oxide. When extrapolated to a year, the annual cost savings for a farm of this size (8,000 piglets) amounts to €25,000 to €30,000 compared to magnesium oxide.
Finally, no more problems with ear rim necrosis — a real game changer!
The clear and reproducible results prompted the trial farm manager to replace 0.75 kg of magnesium oxide with 0.5 kg of anhydrous magnesium sulfate (KaSa Mag98) per ton of feed. This lower dosage meant that the magnesium oxide could be replaced at no additional cost. After one month, the positive effects were noticeable, and the farm manager was highly satisfied.
The piglet group fed magnesium sulfate achieved the highest IOFC (income over feed cost).
Discover now in our webinar: How magnesium sulfate improves piglet rearing
Published in Leading Journals
Our research findings have already been published in recognized journals:
Forum angewandte Forschung
L. Gloede, D. I. Jost, F. M. Augusto, K. Fenske, M. Lütke-Dörhoff, H. Westendarp (2025). Vergleich unterschiedlicher Magnesiumquellen in der Ferkelaufzucht. In: Forum angewandte Forschung in der Rinder- und Schweinefütterung 28./29.04.2025 (DLG), Fulda, Beitrag Nr. 38
FEEDMagazine
Tabeling J. T., Jost D. I., Lütke-Dörhoff M., Fenske K., Westendarp H. (2024). Magnesium reduces stress in piglets: Lower cortisol concentration due to Mg-sulphate. FeedMagazine/Kraftfutter 1-2/2024, 15-20. ISSN: 0023-4427
