Guidance on Safely Rebuilding the Cow Herd

Guidance to rebuild the cow herd safely after drought

One of the greatest challenges for cows in drought conditions is that forage quality and quantity is suboptimal, said Phillip Kesterson, DVM, with Zoetis beef technical services. Based in Bridgeport, Nebraska, Dr. Kesterson has seen drought cycles and their effects several times over the years with his clients.

“As areas begin to recover from a drought, we need to remember that the cow herd may have had insufficient nutrients critical for immune response, for reproduction, and for development of the unborn calf,” Dr. Kesterson said. “Drought can change plant physiology and nutrient bioavailability so the cow’s needs may not be met, thus routine practices like vaccinations, synchronization protocols, and parasite control may not yield the expected results.”

Dr. Kesterson recommends taking a close look at the herd to ensure the body condition of the cows is adequate and improving as the pastures recover. It is critical to make sure the remaining cow herd’s needs are met before considering replenishing cow numbers.

As pastures are restored back to productivity, cow/calf producers will once again be ready to rebuild cow numbers. There are three main approaches to rebuilding cow herd numbers:

  • Buying open replacement heifers
  • Buying bred heifers or cows from a known source private treaty
  • Buying bred heifers or cows through a sale/auction barn

“As we bring new cattle into the herd, the biggest concern is with the health and well-being of your current cow herd,” Dr. Kesterson said. “You are exposing them to other disease pathogens and challenging their immune systems. Following basic biosecurity measures, like quarantining new cattle, can help protect your cow herd.”

Dr. Kesterson breaks down the concerns with each approach to expanding the herd:

  • Buying open replacement heifers
    • This situation can be ideal or potentially problematic, depending on timing between purchase and breeding, potentially limiting vaccination options.
    • A solid vaccination strategy is two doses of a modified-live vaccine, such as Bovi-Shield GOLD FP® 5 VL5, before breeding. The first dose should be given after the heifers have reached maturity (as evidenced by cycling). Allow a three- to eight-week interval and administer the second dose, timed at least 30 days prior to breeding; 45 days is possibly more ideal.
    • If you are less than 30-days from breeding, CattleMaster GOLD FP® vaccines are a strategically sound alternative option because they can be safely administered to any animal at any time.
    • Additionally, a complete health program, including parasite control, is critical to breeding success.
  • Buying bred heifers or cows from a known source private treaty
    • The best situation is sourcing animals from a solid modified-live vaccination program with proper timing of administration, ideally at prebreeding.
    • Less ideal are animals from a program utilizing vaccines not labeled for fetal protection or where vaccinations are inappropriately timed.
  • Buying bred heifers or cows through a sale/auction barn
    • This significantly increases the risk compared to buying privately in the country due to greater pathogen exposure based on the volume of cattle that sell through the auction barn.
    • Comingling presents an increased risk of exposure to pathogens not only to the cow or heifer but also to their unborn calf. They also have increased risk of stress or injury with loading and unloading, sorting on concrete and going through processing facilities.
    • If vaccination history is unknown, utilize CattleMaster GOLD FP 5 , the only commercially available inactivated vaccine that provides fetal protection.  
    • It is critical to observe a six-week quarantine period before commingling new additions with the established herd.  One of the greatest risks is bringing in an animal persistently infected (PI) with bovine viral diarrhea (BVD) virus that could put the herd at risk. A testing strategy for BVD would be well worth the money anytime you bring new additions into the herd.
    • The greatest risk of introducing a BVD PI animal in your herd is purchasing a pregnant animal that is carrying a BVD persistently infected unborn calf. The only way to identify a BVD PI fetus is to test the calf as soon as possible after birth.

“The ideal situation is to quarantine the purchased cattle until calves are born and offspring is tested BVD-free, then you can commingle with little worry,” Dr. Kesterson said. “If you are unable to keep them separate, it elevates the importance of a robust modified-live prebreeding vaccination program in the resident cow herd.”

Dr. Kesterson added that challenges producers face as they start rebuilding the herd are not only the cost of replacement females, but also availability of animals meeting the producer’s criteria. “We come to a fork in the road if we can’t source ideal replacements, we need to evaluate other uses for the land,” Dr. Kesterson said. “We could run yearlings or take in cow/calf pairs. We need to make calculated decisions and realize the consequences of those decisions especially if we choose to buy less-than-ideal replacement females.”

One last reminder from Dr. Kesterson is that as cows are commingled, even adult animals  are more susceptible to other health challenges such as respiratory disease. “One of the first things we think when a dead cow appears in the pasture is poisoning,” Dr. Kesterson said. “Necropsies are critical to determine the cause of death. Mature cows are masters at hiding their symptoms.”

Dr. Kesterson encourages producers to have realistic expectations as they repopulate herds with cattle from outside sources. He said the best approach is to consult your veterinarian to assess the risks and develop a plan prior to adding animals back to the herd. For more herd health information, visit   

Do not use in pregnant cattle (abortions can result) unless they were vaccinated, according to label directions, with any Bovi-Shield GOLD FP or PregGuard GOLD FP vaccine prebreeding initially and within 12 months thereafter. Do not use in calves nursing pregnant cows unless their dams were vaccinated within the past 12 months as described above. To help ensure safety in pregnant cattle, heifers must receive at least 2 doses of any Bovi-Shield GOLD FP or PregGuard GOLD FP vaccine with the second dose administered approximately 30 days prebreeding.

About Zoetis

As the world’s leading animal health company, Zoetis is driven by a singular purpose: to nurture our world and humankind by advancing care for animals. After innovating ways to predict, prevent, detect, and treat animal illness for more than 70 years, Zoetis continues to stand by those raising and caring for animals worldwide — from veterinarians and pet owners to livestock farmers and ranchers. The company’s leading portfolio and pipeline of medicines, vaccines, diagnostics and technologies make a difference in over 100 countries. A Fortune 500 company, Zoetis generated revenue of $8.1 billion in 2022 with approximately 13,800 employees. For more information, visit

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