First calf heifers are often thought of as the foundation of the herd, so it stands to reason that a heifer’s first breeding can be pivotal to her overall success and longevity. Often, both commercial and seedstock producers opt to artificially inseminate (AI) their first calf heifers for various reasons. Regardless, deciding to AI heifers is a process that takes some forethought and planning.
For optimal breeding success, it is advised to breed your heifers when they are 14 months of age, which is usually when they reach full puberty. Erin Freitas, an AI technician and beef sales representative for Select Sires, emphasizes it is crucial to breed heifers when they are ready, not when you are. Waiting until a heifer is mature enough to handle the stresses of breeding and parturition only benefits the producer’s bottom line.
Research continues to prove that nutrition plays a key role in reproductive soundness and fertility. Heifers should be fed at a rate where they can be 65-70% of their mature weight by 14 months. This often means that heifers need more protein, fat and energy then a running age cow. Ideally, heifers should have a body score of about 5 when it comes time to cycle them.
Making sure heifers are on a mineral program tailored to the herd’s specific needs is a good management practice, as well. Depending on what the herd’s mineral needs are, heifers may need to be put on their own pre-breeding mix 60 days prior to breeding. Freitas recommends producers converse with their veterinarian and mineral advisor to ensure their heifers are getting exactly what they need in the days leading up to breeding.
“At the same time you start your heifers on a pre-breeding mineral, they are also going to need a bump in protein. This signals to the body that all is good with the world, so now is a good time to reproduce,” Freitas said.
After the heifers have been properly developed, the time comes to sync up the heifers for breeding. There are two main methods that are used to synchronize estrus in heifers: Melengestrol acetate (MGA), a hormone feed additive, or a controlled internal drug release (CIDR). There are pros and cons to using either method for synchronization, but CIDRs are more commonly used in a range situation because they are inserted and the producer can rest assured each individual heifer is receiving the hormones she needs without daily feeding.
“Two-week CIDRs are kind of the gold standard for heifers. They are the more expensive way to cycle cattle, but they are more straightforward,” Freitas said.
After the CIDRS have been in the heifer for 14 days, they are removed and the heifer is given 16 days for her reproductive system to clean and recover. At the end of those 16 days, heifers are given a prostaglandin, most commonly in the form of Lutalyse or Estrumate, to bring them into heat.
What happens next is ultimately up to the producer and their operation. Heat detecting the heifers and only breeding them when they cycle naturally can lead to higher conception rates, but heifers may not calve as tightly. Fixed-time AI’ing heifers 66-70 hours after their prostaglandin shot could shorten the calving interval, but it requires that all heifers receive a shot of GnRH, which adds up, and conception rates often aren’t as favorable.
Deciding to AI first calf heifers is a decision that should not be taken lightly and picking out the bull is arguably the easiest component. A lot will depend on your operation and the long-term goals you have in place for your herd. Heifer bulls can be expensive and they often reach a point where they become too big to safely live cover heifers anymore.
Artificially inseminating can be a way to effectively breed heifers so they can calve in a timely manner, allowing them more time to recover before breeding again which ultimately can lead to higher retention rates. Further, it allows producers to introduce top-notch genetics into their herds at an affordable price.