Magnesium Oxide 90%, 94% or 99%: A Feed Premix Buyer’s Guide

Magnesium oxide is used as a magnesium source in mineral premixes, aquaculture feed and ruminant nutrition. Winstar Ingredients supplies 90%, 94% and 99% MgO grades, subject to grade and order confirmation. Selecting a grade requires more than comparing the assay number: reactivity, particle characteristics, impurity limits, handling and complete-ration design can all affect suitability.

Understand what the percentage represents

The grade percentage refers to magnesium oxide content, not elemental magnesium. Formulators should convert the declared MgO assay to the relevant elemental-magnesium contribution and account for the full formulation. The current specification and batch COA take precedence over general product descriptions.

Compare the grades on a common basis

• 99% MgO: a high-assay option; request the grade-specific TDS and batch COA.
• 94% MgO: a documented feed-mineral option at MgO ≥94%; confirm all other agreed limits.
• 90% MgO: available on request; confirm detailed specifications and application suitability.

A higher assay does not automatically mean a lower-cost or better-performing premix. Buyers should calculate delivered magnesium, inclusion rate, freight, handling losses and formulation constraints.

Review physical and quality parameters

Ask for particle-size information, bulk density, appearance, moisture and relevant impurity limits. These parameters can influence flow, segregation, dosing and dust control. For ruminant applications, reactivity and the complete ration should be evaluated by the nutrition and technical teams. For aquaculture feed, validate mineral balance and process compatibility in the target species and feed format.

Packaging and import planning

Available packing options include 25 kg bags, 50 kg bags and 1,350 kg bulk bags, subject to grade and order confirmation. Latin American importers should also confirm pallet configuration, container loading, humidity protection, SDS and labeling requirements before shipment.

Supplier qualification checklist

• Current grade-specific TDS, SDS and representative COA
• Assay method and agreed impurity limits
• Particle size, bulk density and handling characteristics
• Packaging, storage and lot traceability
• Destination-market documentation and feed-use requirements
• Sample or pilot evaluation before commercial purchasing

See the Magnesium Oxide product page. For the 90%, 94% or 99% grade, packing, quantity and destination-specific quotation, contact Winstar Ingredients.