North American Veterinary Licensing Examination (NAVLE) Practice Test

The most likely dietary deficiency affecting a herd with multiple calves presenting with fractures is low dietary copper. Copper plays a crucial role in bone development and the overall health of connective tissues. In young animals, adequate copper levels are essential for the formation of collagen and other structural proteins that contribute to bone strength and integrity. When there is a deficiency of copper in the diet, it can lead to impaired bone mineralization, making bones more susceptible to fractures.

Additionally, while hypovitaminosis D can also lead to problems with calcium absorption and subsequently bone health, the connection to fractures due to copper deficiency is more direct and typically observed in specific cases with cattle where copper levels are insufficient. High dietary phosphorus can also cause imbalances but does not directly result in fractures as a primary issue. Lastly, low dietary protein may affect overall health and growth, but protein deficiency alone is less specifically linked to fractures when compared to the role of copper in skeletal integrity.