But first, producers should take some time to evaluate replacement heifers’ health, nutrition and reproductive status. This will increase breeding success with heifers that will perform and are good representation of the females that should enter the mature cow herd.
First, replacement heifers should be given pre-breeding vaccinations at least 30 days prior to breeding to protect them from infectious reproductive diseases, such as leptospirosis, IBR and BVDV. These conditions can be detrimental to fertility as they contribute to embryonic losses in addition to losses later in gestation.
People are also reading…
Heifers may need booster doses of these vaccines, so timing should be carefully considered and discussed with a veterinarian.
Brucellosis, or “Bangs,” vaccination should also be considered. This vaccine is administered by an accredited veterinarian when the heifer is between 4 and 12 months of age. There is no longer a national or state requirement for brucellosis vaccination, but vaccinated animals are better able to move between states (as a result of the orange identification “Bangs tag” applied at the time of vaccination) and are protected against the disease should it show up in the region.
Next, heifers need to have good nutritional management in order to reach a target weight by breeding time.
Heifers must reach puberty by 15 months-of-age if they are to calve by 24 months. Therefore, heifers that reach puberty at an earlier age than their counterparts prior to breeding (due to nutrition, genetics, environment,
etc.) are more likely to experience multiple estrous cycles before the breeding season. This can have a positive effect on conception, leading to earlier calving during her first year and also in consecutive years, allowing her to wean more pounds over her lifetime.
Also, measuring pelvic area is a practice that can be performed in replacement heifers that may be helpful in identifying females that could be prone to future calving difficulty if the pelvic canal is smaller than desired for anticipated calf birth weight. Pelvic area will not likely have an effect on fertility directly; however, it may predict future dystocia events. If dystocia occurs it will decrease pregnancy rates by extending the postpartum period, delaying estrus and reducing conception rates.
Pelvic area is measured using a pelvimeter introduced into the rectum which will measure the height and width of the pelvis at the widest points. These measurements are multiplied together and measures the area in square cm. Average pelvic area for a 600 lb. heifer is 140 cm2 (11.5 cm wide x 12.5 cm high) with the ability to deliver a 67 lb. calf. Pelvic area continues to grow at 0.27 cm2/day until 2 years of age, and then slows through maturity.
These are only some of the management tips that can be implemented into heifer development programs to assist producers in raising heifers that will work for them and keep high-quality females entering the cow herd as replacements year after year.
Anderson, K. J., D. G. Lefever, J. S. Brinks, and K.G. Odde. 1991. The use of reproductive tract scoring in beef heifers. Agri-Practice 12(4): 19.
Perry, G. A., and M. F. Smith. 2014. Keys to Successful estrus synchronization and artificial insemination programs. Applied Reproductive Strategies in Beef Cattle Proceedings; Stillwater, Oklahoma.
Torell, R., G. Veserat, B. Kvasnicka, K. Conley, L. Krysil, and B. Bruce. 2007. Heifer development: the key to a profitable cow herd. University of Nevada, Reno School of Veterinary Medicine.