Home Grown Research EXAMINING TRENDS IN PAP OF YEARLING BULLS ENROLLED IN THE UBIA BULL PERFORMANCE TEST
By Kim Chapman, Extension Livestock Specialist, Utah State University; Matt Garcia, Extension Beef Specialist-Beef Genomics, Utah State University; Mike Walburger, DVM, Arrowhead Veterinary Clinic The Utah Beef Improvement Association (UBIA) has been conducting an annual bull performance test since 1972. The test has been conducted in cooperation with Utah State University Extension and commercial feedlots to house and feed the bulls. In the 33-year period from 1987 to 2020, the UBIA has tested more than 7,700 bulls and sold more than 3,000 high-performance bulls for use in commercial and purebred herds throughout the western U.S. through the UBIA Performance Bull Test sales. The primary objective of the test is to assist cattle producers in obtaining genetically-superior, performancetested bulls that are structurally and reproductively sound. To this end, the UBIA has followed the standards set forth for central bull tests established by the Beef Improvement Federation. Allowing the bulls to grow using a primarily forage-based ration, provides them with adequate nutrients to express their genetic differences, while not pushing them so hard that the integrity of their digestive system is compromised. As the cattle industry has worked to meet consumer demands for higher quality beef eating experiences, the seedstock industry has labored to adapt their cattle to supply the commercial trade with the right type of cattle to meet their needs. This effort has possibly had some collateral side effects not necessarily anticipated during the breeding selection process. This paper will discuss how this effort has impacted Pulmonary Arterial Pressure (PAP) as measured at the conclusion of each testing year of the
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recent history of the UBIA Performance Test (Test). The objective of the current study is to evaluate and note trends and breed differences over 12 years (2008-2019) of PAP data collected on bulls across the test and between four major breeds enrolled in the test. Elevated PAP scores can lead to High Altitude Disease, also known as Brisket Disease in cattle that range at elevations above 7,000 feet, thus the name High Altitude Disease. Calves with high PAP scores are most susceptible to develop swelling throughout the brisket area as the heart works to counteract the effects of hypoxia leading eventually to congestive heart failure. Neary, reported that on one Colorado ranch where cattle were raised above 8,000 feet elevation 50 percent of calves that died between branding and weaning had succumbed to high-altitude disease. Because PAP is a moderately heritable trait (0.38 +/- 0.07), testing prospective herd sires is one of the best ways for a producer to ensure the disease potential of the herd remains low. However, this must be accompanied by culling cows whose calves exhibit susceptibility as Neary, stated that the ranch referred to above had been using low PAP bulls in their bull battery for 20 years prior to the study. PAP testing has become increasingly important not only to cattle producers who run cattle at high altitudes, but also for feedlot operators who are observing higher numbers of cattle on feed that exhibit symptoms of brisket disease at elevations down to 3,000 feet. Neary reported that their study in 2012 had shown that 15 of every 10,000 cattle entering U.S. feedlots died of Right Heart Failure (RHF) (a more clinical description of brisket disease), while Jensen, (1976) reported only three4 cases per 10,000 in four feedlots they studied at an elevation of 5,000’ ft. While these two studies were quite different, they do suggest a definite upward trend in cattle deaths due to brisket disease at elevations much lower than the 7,000 ft. traditionally thought of as the VOLUME 8
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FEBRUARY 2022
