Dolomite in Poultry and Animal Feed — Calcium and Magnesium Supplementation Explained

Introduction

Beyond agriculture and industry, dolomite has a role in animal nutrition as a natural mineral source of calcium and magnesium. Used correctly and at feed-appropriate quality, dolomite can supplement livestock and poultry diets. This guide explains dolomite's role in feed, its benefits and limits, and the quality considerations that matter most — because feed-use standards differ from soil-use standards.

Why Animals Need Calcium and Magnesium

Calcium and magnesium are essential minerals in animal diets:

• Calcium builds and maintains bone, and is critical for eggshell formation in laying hens, muscle function, and nerve signalling.
• Magnesium supports enzyme systems, energy metabolism, and nervous-system function; deficiency in ruminants is linked to conditions such as grass tetany (hypomagnesemia).

Dolomite (CaMg(CO₃)₂) supplies both minerals in one natural carbonate, which is why it is considered as a feed mineral supplement.

Dolomite's Role in Feed

• Combined Ca + Mg source: unlike limestone (calcium only), dolomite provides magnesium alongside calcium, useful where diets are short of both.
• Buffering / alkalinity: as a carbonate, dolomite can contribute to buffering in the digestive system in some rations.
• Free-flowing granular or ground form: easy to blend into feed and mineral mixes.

Important: Limestone vs Dolomite for Poultry Calcium

A crucial nuance for laying hens: their very high calcium demand for eggshells is usually met with limestone (calcium carbonate) or oyster shell, because those provide a high, concentrated calcium level. Dolomite's calcium is "diluted" by its magnesium content, and excess magnesium can interfere with calcium absorption and eggshell quality. So for high-calcium laying diets, dolomite is generally a *supplementary* magnesium-and-calcium source, not the primary calcium source. Formulate poultry diets with a nutritionist and use dolomite where a balanced Ca/Mg contribution is appropriate — not as a wholesale limestone replacement in layers.