A:   First-calf females are a challenge to get re-bred. Because they are still growing, lactating for their first time, and repairing their reproductive tract to get rebred, their interval from calving to their first heat after calving is longer than mature cows. Because of these challenges, I usually don't recommed trying to AI first-calf females because just getting them pregnant by natural service is a challenge enough. First-calves usually won't begin cycling until 55 to 60 days after calving, so use of syschronization protocol before this time, you will not get much of a response. If you do synchronize, use a protocol that uses a progestin that is approved for cows. Unless you are dead-set on AIing, I would get a bull for natural service and consider AIing these females after their next calf. When renting a bull, make sure you don't bring unwanted diseases into your herd, unless the bull you rent is a virgin bull make sure the bull has gone through a breeding soundness examination and vaccinations are current.