What is a requirement for the general care of horses?

Regular cleaning of food and water containers is essential for the general care of horses. This practice ensures that horses have access to clean food and drinking water, which is vital for their overall health and well-being. Dirty containers can lead to the growth of harmful bacteria and illness, negatively affecting a horse's digestive system and overall health. Maintaining cleanliness in these areas helps prevent disease and promotes good hygiene.

In contrast, the other options do not support proper horse care. Providing food only once a day can be insufficient depending on the horses' needs, as they may require more frequent feeding due to their natural grazing habits. Overcrowding horses is not advisable, as it can lead to stress and aggression, compromising their safety and welfare. Regular trimming of a horse's hooves is crucial for preventing lameness and ensuring their mobility, so suggesting that trimming is unnecessary does not reflect accepted best practices in horse care.