Are Your Replacement Heifers Ready For The Upcoming Breeding Season?

By Glenn Selk,

Oklahoma State University Emeritus Extension Animal Scientist

Fall-calving herds will be breeding replacement heifers at the end of the year.  Now is the time to make certain that those heifers are ready for the upcoming breeding season.

Immunize the heifers.  Ask your large animal veterinarian about proper immunizations for yearling replacement heifers.  Replacement heifers should be immunized for respiratory diseases such as IBR and BVD.   Consider giving the heifers a modified live vaccine for longer lasting protection against these viruses. The heifers should receive this vaccination at least one month before the start of the breeding season.  This would also be a good time to include other reproductive disease protection that may be recommended by your veterinarian.  Examples of other immunizations that should be considered include leptospirosis and campylobacter (sometimes called vibriosis).

If a set of scales is available, weigh the heifers.  There is time to make adjustments to the supplementation being fed to the heifers to insure that they meet the target weight at the start of the breeding season.  To be certain that a high percentage of heifers are cycling at the start of the breeding season, they must weigh a minimum of 60% of their mature weight (Davis and Wettemann:  Relationship between weight at puberty and mature weight in beef cattle).  If these heifers will eventually grow into 1200 pound cows, then they must weigh 720 at the beginning of the estrous synchronization and artificial insemination (or bull turn-out if natural breeding is used).  Calculate the weight gain needed between now and the start of the breeding season to see if additional energy is required to achieve the desired weight gain.

Source: Relationship between weight at puberty and mature weight in beef cattle

Many small cow calf operations will not have scales available to monitor weight gain.  The next best evaluation tool is to monitor the body condition of the heifers.  If all of the heifers are in a body condition score of 6 (based on the 1 to 9 BCS system) then they should meet the desired target weight.

Source: ufl.edu