What is necessary for calves when preparing them for a show?

Preparing calves for a show primarily involves getting them accustomed to being handled and led by a person, which enhances their training and presentation. Breaking them to lead is crucial because it allows the handler to guide the calf effectively during the show. This practice helps in building a positive relationship between the animal and the handler, while also instilling discipline and ensuring that the calf is calm and manageable in the showing environment.

The other options suggest practices that are generally not beneficial for preparing calves for a show. For instance, keeping them in isolation could lead to stress and lack of socialization, which is counterproductive for animals that will be in a competitive setting amongst others. Feeding calves exclusively grain is not advisable as a balanced diet that includes forages is essential for their health and growth. Limiting water intake can cause dehydration and negatively impact the calf's performance and appearance during the show. Therefore, the emphasis on breaking calves to lead is foundational for successful show preparation.