Cattle

A cow in England. (DW: Image of the Fendahl)

Cattle were domesticated mammals native to Earth. Females of the species were also called cows. (DW: Image of the Fendahl) Clyde Langer once succinctly said that "cows eat grass, and they make milk and they go moooo . . . [and] they also make steak." (SJA: Sky)

Encounters with cows

The Doctor and his companions and acquaintances occasionally dealt with cattle. The Eighth Doctor, Charley, and C'rizz encountered cows in the Garden of Curiosities. (BFA: Caerdroia) The Fourth Doctor once landed the TARDIS amongst a herd of cattle and facetiously asked them if they had a time scanner, to no avail. (DW: Image of the Fendahl) The Sixth Doctor and Peri witnessed the heavens open up to dump cows on the beaches of Ostend, Belgium. (BFA: Year of the Pig) When she was briefly a vampire, Nyssa feasted on the blood of a cow in the fields outside Manchester in the 1990s. (MA: Goth Opera)

Bernice Summerfield once experienced a freak time anomaly in which leather shoes were turned back into cows. However, the time anomaly only restored the cows a point shortly before they were turned into leather. Thus, the floors of the Gigamarket were littered with dead cows. (BFBS: The Greatest Shop in the Galaxy)

Dr Scotus, a veterinarian working near Cardiff, once examined a cow that had begun eating other cows, because it had been affected by an alien tapeworm which had come through the rift. (TWN: Slow Decay)

Even the Doctor's enemies used cows. Zygons once used body-print technology to take the form of cows as they were allowed to roam freely. As was necessary for the proper operation of body-print technology, the Zygons stored the real cows in their ship. (NSA: Sting of the Zygons)

Once humanity became a space-faring race, they took cows with them to the stars. As Earth's influence spread, cattle were shipped off the planet across the galaxy, such as Jadea. (EDA: Placebo Effect) Humans also brought cattle to Sarath. (PDA: City at World's End)

References

In addition to actual encounters with cows, there were a number of cases in which cows were referenced:

• On the planet Dido, Barbara speculated that David Campbell was teaching Susan how to milk cows on post-Dalek Earth. (DW: "The Powerful Enemy")
• Though some believed it a myth, the Eighth Doctor claimed that cattle could tell when it was going to rain and would sit down so that they would have a patch of dry grass to eat from. He stated that, like cows, he could tell when it was going to rain, and when something was wrong. (EDA: Placebo Effect)
• Professor Chronotis commented that he could alleviate his lack of milk by keeping a cow. (DW: Shada, WC: Shada)
• On Voga, Sarah Jane's ankles were bound by chains. In the attempt to free her, Harry accidentally hit one of her ankles. When it became swollen, he told her that the ankle was as "thick as a cow's". (DW: Revenge of the Cybermen)
• The Second Doctor noted that cows were always very friendly to him. (ST: One Small Step...)
• King Garth offended the natives of Corpos Delta when he compared them to cows. (EDA: Placebo Effect)
• When explaining to the Doctor and Rose Tyler that the Ood were a herd race, Danny Bartock compared them to cattle. (DW: The Impossible Planet)
• The Editor of Satellite Five referred to humanity as cattle. (DW: The Long Game)