It's pretty insulting nowadays to call a woman a "cow", because that implies that she is fat - and nowadays fatness is quickly approaching promiscuity as the most undesired female trait. Things did not always used to be this way. In the Biblical era it was common for women to be named after large herbivorous animals, and nobody saw anything wrong with it.
Take for example the name Rachel, which means "female sheep". Or Yael, which means "ibex" - a kind of large wild goat. And let us not forget Rivkah, whose name, according to some commentators, means "cow" or "female calf". (See Shmuel 1 28:24, Yirmiyahu 46:21, Amos 6:4, Malachi 3:20 for comparison). My sister might not want to learn that she's named after a bovine, but the original Rivkah would have had no such hesitation.
UPDATE: One more example. The name "Leah" means "cow" in Akkadian.
Looking more closely, we see that these names are not evenly distributed across all Biblical women. Rather, they seem to only appear in families whose profession was herding. Rachel and Rivkah came from the family of Lavan the Aramean, and Yael from the nomadic Kenite tribe. Certainly Lavan, and probably the Kenites too, made a living from herding rather than farming or trading.
From the nature of the herding lifestyle, we can understand why these names became respectable. Herders would watch over and care for their animals - feeding and guiding them and caring for their sicknesses. In turn the animals would provide offspring and create wealth for the herder. This symbiotic relationship reminded ancient people of the relationship between husband and wife. While it's not politically correct to compare the two, wife and flock played similar roles in pastoral society: providing wealth and a future for the herder, who in turn protected them and guided them through the outside world.
The same comparison between wife and flock appears in other contexts. For example, the prophet Natan accuses David Hamelech of adultery through the parable of "kivsat harash", in which a rich man steals the only female sheep of a poor man, which the poor man had raised "in his lap... like a daughter". Here, the love and care the poor man gives to his sheep represent the the love and care which Uriyah felt towards his wife Batsheva, which were violently intruded upon by David's adultery.
The relationship between God and humans is often likened to that of husband and wife, and it's not surprising that it's likened to that between shepherd and flock as well. Thus we find well-known comparisons such as "Hashem is my shepherd, I shall not lack" (Tehilim 23:1) which is sung every week at seudah shlishit.