Final answer:
The three infectious causes of pinkeye in cattle are Moraxella bovis, Chlamydia psittaci, and Mycoplasma bovoculi, which lead to inflammation and discharge in the affected animal's eye.
Step-by-step explanation:
The three infectious causes of pinkeye (infectious bovine keratoconjunctivitis) in cattle are Moraxella bovis, Chlamydia psittaci, and Mycoplasma bovoculi. These organisms can cause varying types of eye infections, leading to inflammation and discharge which characterizes conjunctivitis. Moraxella bovis is often associated with flies that act as mechanical vectors, transmitting the bacteria from animal to animal. Chlamydia psittaci, while also known for causing psittacosis in birds, can lead to infectious bovine keratoconjunctivitis. Mycoplasma bovoculi has also been linked to outbreaks of pinkeye in cattle.