Metabolism of some essential minerals in ponies fed high levels of aluminum.

The study looks at how dietary aluminum intake impacts the absorption, retention, and excretion of minerals like calcium, phosphorus, magnesium, zinc, iron, and copper in ponies. The research found that a diet high in aluminum disrupts the balance of phosphorus and calcium in the body, affecting bone formation and turnover.

Study Design

• The research study was conducted as a balance trial in adult ponies using a three by three latin square experiment design, which is a popular method in agronomic experiments for testing the reaction of different species to various levels of factor combinations.
• A diet, balanced with one-third each of oats, beet pulp, and a commercial pelleted complete horse ration, was prepared. This basal diet had a base aluminum concentration of 336 ppm (parts per million).
• In addition to the basal diet, the researchers conducted trials with two other diet levels, a middle level, and a high level, which contained 1370 ppm and 4500 ppm of aluminum respectively.

Key Findings

• There was no significant impact on the absorption, retention, and excretion of essential minerals between the middle-level aluminum diet and the basal diet.
• Ponies put on the high-aluminum diet, however, exhibited a negative phosphorus balance due to suppressed phosphorus absorption.
• Even though aluminum intake did not directly affect calcium absorption, it indirectly caused a negative calcium balance. This was a result of increased urinary excretion, possibly triggered by the lack of phosphate needed in the formation of bone crystals.
• The plasma or blood levels of both calcium and phosphorus were affected by the high aluminum diet. Plasma calcium levels escalated while plasma phosphorus levels decreased.
• An increase in plasma hydroxyproline concentration suggested an escalation in bone turnover likely driven by the effects of aluminum on phosphorus and calcium metabolism.
• Aluminum intake did not impact the metabolism of magnesium, zinc, iron, and copper in the tested ponies.

Interpretation

• This study implies that a diet high in aluminum can have negative impacts on phosphorus and calcium metabolisms in ponies, disrupting the balance of these essential minerals, and potentially affecting bone health.
• While aluminum does not directly affect the actual absorption of calcium, it impacts how calcium is utilized and excreted in the body.
• Even though adverse effects were only noticeable in the high level aluminum diet, long-term intake of aluminum in smaller amounts could potentially pose a risk to the health of animals.