Cows with _____ have a higher incidence of mastitis because physical injury is more likely.

Cows with pendulous udders are more prone to physical injury due to the structure and weight of the udder hanging lower than usual. This makes them more susceptible to trauma from their environment, such as bumping into objects or from rough handling during milking. The increased risk of injury can cause stress on the tissue of the udder, leading to inflammation and a higher likelihood of mastitis. Mastitis is an infection of the mammary gland that is often triggered by physical damage to the udder, making the health and condition of the udder crucial for dairy cows. Other options like having healthy hooves or short legs do not inherently increase the risk of udder injuries or mastitis, nor do large udder openings directly relate to a higher incidence of injury compared to the structural issues posed by pendulous udders.