Bull Evaluation and Selection

 

This is the time of the year when cattle producers are taking their bulls out of the pasture, evaluating them, to determine if the current bull is acceptable for the next breeding season or if a new bull needs to be purchased.  Evaluation of the bull should determine if he is meeting the cattle operation goals or if the purchase of a new bull will improve the likelihood of meeting those goals.  The physical abilities of the bull also need to be evaluated to determine if he is sound and can continue to breed females during the next breeding season.  Cattle producers also need to think about significant traits that need to be improved upon to make the cattle operation more successful in meeting their goals and determine if the current bull is acceptable or if a new bull needs to be purchased to improve those traits.  If the decision is to purchase a new bull, take into account as much information as possible, as well as physical attributes, and purchase a bull that will make your cattle operation more successful.

 When evaluating the current bull or selecting a new bull it is important to make sure the bull is adequately conditioned, muscled, and sound in structure.   The bull should have a strong level topline and flexibility of structure such that on the move the bull walks smooth with ease. Also, the bull should have average shape and dimension of muscle throughout the body. The bull should be average frame size, with a deep wide chest floor, and bold spring of rib.  When evaluating your current bull since he has been working his condition may be a 5 or slightly less, it is important to look at how he maintains his condition and how he puts on condition once the breeding season is over.  If the bull is efficient in maintaining condition by not losing to much during the breeding season and efficiently putting the condition back on after the breeding season then he is acceptable.  However if your bull is not managing his condition efficiently then it is time to cull him and purchase a new bull.  When purchasing a new bull you should evaluate him and take into account the same physical attributes as you would your current bull with the exception of body condition score.  Newly purchased bulls should have a body condition score of 6 (bull exhibits a good smooth appearance throughout).

Another test that determines if your bull can reproductively breed cows is a breeding soundness exam.  Current bulls should have this test done and be satisfactory before the next breeding season and newly purchased bulls should have the test done and be satisfactory before you take possession.  Also newly purchased bulls need to be tested and found negative for Trichmoniasis, an organism found in the reproductive tract of bulls and cows that leads to infertility, low pregnancy rates and abortions in cows.    

When evaluating current bulls or bulls you are looking at purchasing it is important to look at the genetic merit of the bulls in addition to the physical attributes of the bulls and retain bulls that can genetically and physically make your cattle operation more successfully in meeting its goals.  The easiest tool to use in evaluating genetic merit of a bull is expected progeny differences (EPDs) which is a measurement of the animal’s genetic value as a parent.  When comparing two bulls the difference in EPDs is the expected difference in progeny performance between two bulls.  For example, if bull A has a calving ease EPD of +0 and bull B has a calving ease EPD of +15 then bull B would have 15% more unassisted births compared to bull A.  A new way to categorize EPDs is through EPD percentile ranks which will allow you to compare your current or purchased bull to all the rest of the bulls in the breed for that trait.  For example, a bull that is in the 25th percentile rank for calving ease means that he is in the top 25 percent of all bulls in the breed for calving ease.  Furthermore, if you had two bulls that you were evaluating and bull A was in the 25th percentile rank and bull B was in the 75th percentile rank for calving ease then bull A would have calves with more ease than bull B.  Identify traits that will help your cattle operation be more successful at meeting its goals and retain bulls to use that have better than average EPDs and EPD percentile ranks of less than 50% for those traits.  Finally another part of EPDs that is important is accuracy of the EPD.  Basically the higher the accuracy of the EPD the more reliable the EPD.  You should use bulls with EPDs with the highest accuracy possible.  Some bulls that are being sold have gnomic enhanced EPDs which means the bull had a DNA test done and it improved the accuracy of his EPDs.  Therefore, since these bull’s EPD’s accuracy is higher you should probably look at purchasing bulls with genomic enhanced EPD’s when possible.

When making a decision on the next bull that you’re going to turn in with your cow herd always have your goals in mind and make sure the bull has the physical and genetic attributes that will be successful in improving traits to meet the goals of your cattle operation.  If you have any questions contact your local MU Extension Livestock Specialist. 

Source: Patrick Davis, Livestock Specialist