Tips for Developing Replacement Females

ALEDO, Texas (May 15, 2008) – To run an efficient and progressive beef cow production system it is important to effectively develop replacement females. Developing a sufficient number of heifers that are cycling at the beginning of the breeding season helps to assure they will breed early in the first year. Early breeding translates to earlier calving and heavier weaning weights.

“Because replacement females will not begin to produce an economic return until they are around three years old, when they wean their first calves, they are an expensive enterprise,” says Glenn Rogers, DVM, Pfizer Animal Health. “Heifers are in danger of failing to meet their reproductive and economic potential if they aren’t developed correctly.”

To effectively develop replacement females, Rogers recommends focusing on two key areas: setting cost-effective goals and developing the immune system.

Setting Development Goals

Careful consideration should be given to the costs associated with on-ranch heifer development vs. the purchase of bred heifers. Cow/calf operations are sometimes ill-equipped to efficiently develop their own heifers, and many times high-quality bred heifers can be purchased for less than the actual cost of on-ranch development.

If purchasing heifers, a careful analysis of the previous health and production history should occur.

If a decision is made to develop rather than purchase, goals should be set to achieve growth, reproductive and economic objectives. Rogers encourages producers to consider the following tips when setting development goals:

  • Approximately 10 to 25 percent more heifers than needed should be in the initial pool to allow for heifers that fail to meet reproductive and growth targets.
  • Estrous synchronization and artificial insemination can lead to improved genetics, a tighter calving period and may offer economic advantages in some operations.
  • The traditional target weight (65 percent of projected mature weight) for heifers at breeding has been assumed to be optimal for reproduction. However, it may not be economically sound in many production systems. Recent information shows satisfactory reproductive performance can be achieved after developing heifers to a slightly lower percent of projected mature weight than mentioned above.1 In light of drastically increased input costs, traditional target weight goals may need to be re-evaluated.

Developing the Immune System

The heifer immunization program is the foundation for cow herd immunity. Substantial carry-over effect in herd immunity occurs when a sound health management program for heifers is in place. And, because heifers generally have less immunity to reproductive diseases than mature cows, a sound pre-breeding vaccination program is essential in order to provide heifers with protective immunity during breeding and throughout pregnancy.

The vaccination program for heifers pre-breeding should include:

  • Modified-Live Viral Vaccine such as Bovi-Shield GOLD® FP®,* for protection against IBR abortions and BVD Types 1 and 2 persistent infection. It is recommended that heifers receive at least 2 doses, with the second dose administered approximately 30 days prior to breeding.
  • Leptospirosis Vaccine including hardjo-bovis and Campylobacter fetus (vibrio) with a product such as SPIROVACâ VL5.

Pfizer Inc. (NYSE: PFE), the world’s largest research-based pharmaceutical company, is a world leader in discovering and developing innovative animal vaccines and prescription medicines. Pfizer Animal Health is dedicated to improving the safety, quality and productivity of the world’s food supply by enhancing the health of livestock and poultry; and in helping companion animals live longer and healthier lives. For additional information on Pfizer’s portfolio of animal products, visit

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* LABEL INDICATIONS: The Bovi-Shield GOLD line and PregGuard® GOLD FP 10 may be administered to pregnant cattle provided they were vaccinated, according to label directions, with any Bovi-Shield FP or PregGuard FP vaccine prior to breeding initially and within 12 months thereafter. Failure to follow label directions may result in abortions. The Bovi-Shield GOLD line of products may be administered to calves nursing pregnant cows provided their dams were vaccinated within the last 12 months as described above. Consistent with good vaccination practices, it is recommended that heifers receive at least 2 doses, with the second dose administered approximately 30 days prebreeding.

1 Funston RN, Deutscher GH. Comparison of target breeding weight and breeding date for replacement beef heifers and effects on subsequent reproduction and calf performance. J Anim Sci 2004. 82:3094-3099.

Bovi-Shield GOLD, FP, PregGuard and SPIROVAC are registered trademarks of Pfizer Inc. ©2008 Pfizer Inc. All rights reserved. GCC08009

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For further information, contact:

Jennie Schutte

Pfizer Animal Health


[email protected]

Kenna Rathai



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