Well..Bill is right..12 months is a tad young, but it depends on the particular bull & the breed also. The bull should show "interest" in the cow every 21(+/-) days..if 21 days go by after he does & he ignores her..then she is most likely pregnant. I raise Longhorns & they are famous for their fertility, the youngest I had a bull breed a heifer (oops!) was 11 months..I believe Jerseys have a similar reputation. Brahmans in general mature much later sexually. I would think just about all breeds would be fertile by 14-16 months. Ultrasound is an early option, but fairly expensive. Palpation (manual examination by vet) is much cheaper, but the cow should probably be bred about 45 days to be sure of a correct reading!
> We are new to owning cows, and we
> have one 2yr old heifer and one
> 1yr old bull. We would like to
> know how do we tell when the
> heifer becomes pregnant. We would
> like her to be pregnant before we
> send the bull off to slaughter.