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Texas A&M College of Veterinary Medicine & Biomedical Sciences Update

published: October 31st 2008
by: Brandon Broyles
source: Texas A&M University

Pounds of Calf Weaned per Female Exposed: How Do You Stack Up?
Brandon Broyles
Class of 2010
Texas A&M College of Veterinary Medicine and Biomedical Sciences
    A ranch economist friend of mine told me once that you can only manage what you measure.  That statement couldn’t be more applicable to today’s cattle operations.  A key component of success in the future will be those who can adapt to the changing cattle markets.  It begs the question: “How do you adapt when you don’t know where you are?  How can you plan for the future when you don’t know where you’ve been?  Let’s take a brief survey of basic production parameters for the cow/calf operation.  Can you answer the following questions: Do you know the following percentages from last year’s records (pregnancy %, calving %, and weaning %)?  How many females were exposed?  Can you answer this key production parameter: POUNDS OF CALF WEANED PER FEMALE EXPOSED?  Over the years much attention has been placed on weaning weights.  Some careful consideration needs to be paid to an awareness of the relationship of pregnancy rates, weaning weights and weaning rates.  We need to maximize the number of calves we get on the ground and then to the market of choice. 
    Consider the following example: A producer has a 200 cow herd and has an 80% weaning rate, with a 500 lb weaning weight, this producer will have 80,000 lbs of cattle to market.  If you boost the weaning rate to 84%, total pounds weaned will increase to 84,000 lbs.  What do you think about the weaned calf percentage of 84%?  Standardized performance analysis (SPA) data from Texas ranches for a 10 year period (1991-2001) showed the impact of weaning % and #’s of calf weaned per female exposed and ranch profitability.   The top 25% of participants weaned 84% of calves at an average WW of 551 lbs resulting in 463 lbs of calf weaned per female exposed.   Compare those figures to the bottom 25% of the participants that weaned 80% of calves at an average WW of 501 lbs resulting in 404 lbs of calf weaned per female exposed.
    The point I would like to make is that increasing weaning weight is a positive thing, but why not tack on some more calves to go along with that. There are many components to this critical management value.  However, breaking these components down into categories that can be addressed and resolved will make it more approachable.  As you take this approach it is worth noting that the long term success of the operation is the goal here, not just the next calving season.
    BCS and Nutrition:  The best way to monitor the nutritional status of the herd is through Body Condition Scoring (BCS).  A good rule of thumb is to have the cows calving at a BCS score of 5 and heifers at a BCS of 6.  Drought and high feeding costs can lead to poorer conditioned cattle. Based on work done in Texas, the difference in conception rates between cattle with a BCS score of 3 and 5 is significant (50% and 90% respectively). 
    Infectious infertility: There are a number of infectious agents that can reduce conception rates and therefore reduce the number of live, healthy calves that hit the ground.  BVD, IBR, Brucellosis, Campylobacter (vibrio), Leptospirosis (lepto), Neosporosis and Trichomoniasis (trich) are all diseases to be aware of as a cattle rancher.      Awareness of disease leads to better management. For example, research out of Florida indicates that a rancher that was not aware of Trichomoniasis was 3.3 times more likely to have the disease in their herd when compared to those that were aware of the disease.  The good thing about each of these diseases is that proper management can go a long way in controlling and preventing them.  Biosecurity and herd health planning should be discussed with your veterinarian to minimize the threat of infectious causes of infertility to your ranch.  Vaccination protocols should be made with the help of your veterinarian in order to keep these profit robbing diseases from affecting your operation.  Further, venereal diseases such as Trich can be prevented with sound biosecurity practices (purchasing virgin bulls, testing mature bulls prior to breeding season, and monitoring pregnancy rates).  Bulls should only be bought from trusted sources and should be tested before they are used.  Additionally we should try to keep our herds as closed as reality permits to decrease the chances of buying a disease.
    Breeding soundness exams are recommended annually on all breeding bulls.  Remember, a bull can become unsound at any time and waiting for calving season to find out can be costly!  Improper bull selection resulting in dystocia (difficult birth) can affect early calfhood performance as well as delay re-breeding in the dam.  First calf heifers should not be bred to high birth weight bulls.  When choosing a bull, it is wise to consider what they will be bred to.  Cow frame size should be evaluated against the frame size of the bull and his EPD’s (expected progeny difference). 
    Reduce neonatal calf morbidity and mortality:  Healthy cows are more likely to raise healthy calves.  Early calfhood sickness and death losses can wipe out the benefit of even the best of pregnancy and calving rates.  Any calf losses or illness should be discussed with your veterinarian and not just assumed to part of the business.     
    Knowledge of key production parameters such as Preg %, Calving %, Weaning %, WW, and Lbs. of calf weaned per female exposed will give you the information you need to assess the success of your ranching operation and help guide you to goal setting for future performance.  Awareness of commonly occurring causes of infectious infertility, along with solid record keeping and biosecurity will get you on the path to success in an ever changing cattle market.