Question

The requirement of which one of the following trace minerals is least in the diet of farm animals

• A. Selenium
• B. Iron
• C. Zinc
• D. Copper

Hint:

Remember that the margin of safety for Selenium is very narrow. While animals require only \(0.1 \text{ to } 0.3 \text{ ppm}\), concentrations above \(5 \text{ ppm}\) can cause chronic toxicity, known as "alkali disease" or "blind staggers."

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Essential mineral nutrients are divided into macrominerals (required in grams per day) and microminerals or trace minerals (required in milligrams per day or parts per million, ppm). Within the trace minerals, the required concentrations vary significantly.

Step 2: Detailed Explanation:
Let us compare the nutritional requirements of the given trace minerals in standard livestock diets:

Iron (Fe): Iron is required in relatively large quantities among the trace minerals, typically in the range of \(50 \text{ to } 100 \text{ ppm}\) (mg/kg of diet) to support hemoglobin synthesis and oxygen transport.

Zinc (Zn): Zinc is essential for a wide variety of enzyme systems, skin health, and immune function, with typical dietary requirements ranging from \(30 \text{ to } 50 \text{ ppm}\).

Copper (Cu): Copper is necessary for hemoglobin synthesis, iron mobilization, and connective tissue formation, with standard requirements ranging from \(10 \text{ to } 15 \text{ ppm}\).

Selenium (Se): Selenium is an essential component of the antioxidant enzyme glutathione peroxidase, which protects cell membranes from oxidative damage.
Because it is highly active at extremely low concentrations and becomes toxic at slightly higher levels, the dietary requirement for selenium is very low, typically standardized at only\(0.1 \text{ to } 0.3 \text{ ppm}\) (mg/kg) in the total dry matter.
Comparing these values, the dietary requirement for selenium is the smallest among all the essential trace minerals listed.

Step 3: Final Answer:
The correct option is (A), representing Selenium.