Final answer:
d. Infected uterine discharge
Klebsiella mastitis is commonly caused by infected uterine discharge and is a concern in dairy farming due to its impact on milk production and quality.
Step-by-step explanation:
A common source of Klebsiella mastitis is infected uterine discharge. This type of infection usually occurs when bacteria from the environment contaminate the mammary gland, often during the milking process. The infection is particularly associated with dairy cattle and is a concern in dairy farming and animal husbandry because it can impact milk production and quality.