cent lower pregnancy rates due to ovarian dysfunction, failure of fertilization, early embryonic death or mid-gestation fetal loss. Nearly 20 percent of BVD-PI caves died before weaning. New arrivals to the herd should be tested
for BVD to determine if they are persistently infected animals. When records indicate reproductive performance is below expecta- tions, consider BVD as the culprit. A stra- tegic testing program that fi ts the specifi c operation may be needed.
Select on reproduction A beef heifer should produce her fi rst calf
at 2 to 2-1/2 years of age and then continue producing a calf once every year throughout her mature life. To ensure that she will breed back every
year, select females from genetic lines with a history of early pregnancy and then judge the heifer’s actual breeding performance in the herd. The heifer’s breeding season should be scheduled
Glenn Rogers, DVM, is the owner and operator of Holt River Ranch and Grassy Ridge Consulting. A primary enterprise of the Holt River Ranch is heifer development.
ahead of the cow breeding season to increase her op- portunity to breed back as a fi rst-calf heifer. The old adage, “once late, always late,” is usually true when it comes to heifers’ ability to get bred early in their fi rst breeding season and her subsequent breeding perfor- mance as a cow. There are many methods of culling heifers based on
reproductive capabilities. A more extreme example is to artifi cially inseminate (AI) heifers at a fi xed time, keeping only the AI pregnancies and selling the rest. A second method is to leave a bull with the heifers for 90 days and keep only those bred in the fi rst 45 days. Regardless of the method used, keep the heifers on an increased nutrition level prior to and through the breeding season, and ensure that the bull is fer- tile and has a strong libido. Additional culling tools include pelvic measurements and reproductive tract scoring (RTS).
Estrus synchronization and AI Estrus synchronization and AI may deserve a closer
look in commercial beef herds because of improvements in timed AI programs and the high costs of bulls. The fi rst step in taking advantage of the opportunity to improve breeding economics is to adopt estrus syn- chronization as way to shorten the calving season. An advantage of estrus synchronization is more calves
tscra.org
born earlier in the calving season, resulting in heavier weaning weights. It also allows for more effi cient use of labor during calving season. Synchronization is necessary for effi cient use of AI. Cow-calf operators might want to consider AI be-
cause of the ability to enhance herd genetics more economically than buying bulls of the same quality. AI provides a high accuracy of sire-expected progeny differences (EPDs) for traits such as calving ease. It also saves the rancher the cost of maintaining as many bulls during the year. Rogers has found estrus synchronization and AI to
be effi cient and economical tools in his heifer develop- ment programs. Rogers likes his value-added heifer business because
it is a mixture of the reproductive side of a cow-calf business with the margin opportunity of stocker en- terprises. Heifer development is a niche opportunity that is
well established in the dairy industry. It provides a better opportunity for intensive grazing management because cattle can be moved without calves. The en- terprise complements a hunting program and range management goals. There is less risk in heifer develop- ment than a pure stocker operation if you have space to “make cows.” A cow-calf operator can study the 3 options for heifer
development and select the option that best fi ts his or her management style and economics.
April 2015 The Cattleman 83
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