Feeding Trials: Magnesium Sulphate vs. Magnesium Oxide
In collaboration with the Faculty of Agricultural Sciences at Osnabrück University of Applied Sciences, the impact of magnesium sulphate instead of magnesium oxide on piglet health and growth was investigated.
The feeding trials were conducted in a piglet rearing barn (8,000 piglet rearing places) in Rheine at the river Ems. The family-run farm has been involved in animal husbandry for five generations and regularly conducts practical trials with the university to optimise pig farming. Several feeding trials with anhydrous magnesium sulphate (KaSa Mag98) have already been carried out here.
Magnesium in Piglet Rearing
Adequate mineral supply supports healthy physical development and well-being – not only in humans but also in animals. A research project initiated by K+S has now confirmed the benefits of magnesium sulphate in piglets. Especially at the beginning of piglet rearing, weaning from the sow, relocation, feed changes, and new group formation lead to a stressed general condition in piglets.
Magnesium oxide (MgO) is commonly used in piglet rearing due to its availability on the market, low cost, and apparently high magnesium content. The higher price of alternative magnesium sources deters many livestock farmers, although these may offer better bioavailability.
Piglets were divided into groups for the trials. One group received the usual piglet feed with magnesium oxide, while the other received the same amount of anhydrous magnesium sulphate. The dosage was 0.75 kg/t in the first trial and 0.5 kg/t in the second. A control group without magnesium supplementation was also included in the second trial. Feed intake, body weight, medication use, injuries, and faecal consistency were documented throughout the trial. Stress levels in the animals were measured via cortisol concentration in saliva. Cortisol is a steroid hormone and a key messenger in stress responses. In threatening situations, cortisol helps mobilise energy and supports the fight-or-flight response. For stress-free sampling, a cotton rope was hung in each pen for 30 minutes. The piglets chewed on the rope, leaving saliva samples.
Magnesium Sulphate Increases IOFC
Adding magnesium sulphate instead of magnesium oxide at the start of piglet rearing reduces stress and leads to higher body weight. Despite the higher product price, improved feed efficiency results in a higher IOFC.
Compared to magnesium oxide, magnesium sulphate supplementation led to:
- Generally lower cortisol levels
- Significantly higher daily weight gains
- Numerically reduced medication use
- Economic advantages (higher IOFC)
The magnesium in our product is completely water-soluble and therefore fully available to the animal. In contrast, only around 10% of the magnesium in magnesium oxide, depending on the animal species, is available – the rest is simply excreted.
Higher Weight Gain
Throughout the rearing period, piglets in the magnesium sulphate group gained more live weight than those in the magnesium oxide group. Feed conversion was generally better with magnesium sulphate.
Piglets fed with magnesium sulphate showed a significant higher live weight and a better feed conversion ratio than the groups fed with magnesium oxide or without magnesium supplementation.
Less Stress and Fewer Medications
Cortisol concentration in saliva continuously decreased over the trial period in the magnesium sulphate group, unlike in the magnesium oxide group. This indicates better stress reduction.
Medication use was more than twice as high in the control and magnesium oxide group compared to the magnesium sulphate group, resulting in lower treatment costs of 10 Euro cents per piglet.
Piglets fed with magnesium sulphate were less stressed (lowest saliva cortisol concentration) compared to the groups fed with magnesium oxide or without magnesium supplementation.
Piglets fed with magnesium sulphate needed less than half as much medication compared to the groups fed with magnesium oxide or without magnesium additive.
Higher Profitability
The economic calculation (IOFC), including treatment costs, showed an advantage of 52 cents per animal for the KaSa Mag98 variant compared to magnesium oxide. Even the negative control without magnesium supplementation was around 20 cents more economical per piglet than the control variant with magnesium oxide.
For a farm of this size (8,000 piglet rearing places), the annual cost savings compared to magnesium oxide amount to €25,000 to €30,000.
Finally, no more problems with ear rim necrosis — a real game changer!
The clear and reproducible results led the farm manager to switch from 0.75 kg of magnesium oxide to 0.5 kg of anhydrous magnesium sulphate (KaSa Mag98) per ton of feed.
Due to the lower dosage required for magnesium sulphate, magnesium oxide could be replaced cost-neutrally.
After just one month, a positive effect was already noticeable, and the farm manager was highly satisfied.
The highest Income Over Feed Cost was achieved with the piglet group fed with magnesium sulphate.
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
