Name two roles of calcium in dairy cows that relate to milk production and health.

• A. Bone formation and hair growth.
• B. Digestive enzyme production.
• C. Oxygen transport.
• D. Muscle and nerve function, and blood clotting.

Answer: (D)

Calcium’s roles that matter here are its support of muscle and nerve function and its role in blood clotting. In dairy cows, milk let-down relies on the contraction of the udder’s muscle cells, which is driven by calcium entering muscle fibers in response to oxytocin. Adequate calcium thus helps ensure milk is released efficiently and supports the cow’s overall ability to milk well. Calcium is also essential for proper nerve signaling, coordinating movement and metabolic processes that keep the cow healthy during lactation.

Beyond this, calcium is a key player in the blood clotting process. A healthy clotting response is crucial around calving and after injuries, helping prevent excessive bleeding and supporting recovery, which in turn supports ongoing milk production and overall health.

The other options don’t align as clearly with these two practical roles: bone formation and hair growth aren’t tied to the immediate functions of producing milk or maintaining health during lactation; digestive enzyme production and oxygen transport aren’t primary functions of calcium in this context.