Georgics, book 3, lines 49-65

One man breeds horses, having set his sights
on winning glory at Olympia;
another values strength in bullocks, for the plough.
For each, the chief concern
must be the shape and fitness of the dams.
The ideal breeding cow looks fierce,
with ugly head, thick neck
and dewlap hanging down from chin to knees.
Her sides are long, as long as you could wish;
each bit of her is over-sized, even the feet.
Her ears are shaggy, under crooked horns.
I’m not unhappy if
her hide is spotted white,
she bucks each time she feels the yoke,
those horns can do you damage
and her face is like a bull’s.
She’s tall from poop to stern
and, as she steps, she sweeps her footprints
with the tip of her long tail.
Her best age as a mother
is between her fourth year and her tenth;
before and after that she’s neither fit for breeding
nor robust enough to pull the plough.
So use that time, while you have youth and vigour
in your herds; release the males
and bring your cattle to their coupling without delay;
that way you’ll add successive generations to your stock.