Working Ranch Magazine January/February 2025

Test to the Robust on improving post-weaning perfor mance, carcass size, and carcass qual ity. However, little attention has been given to this selection process’s unin tended effects on immune function and herd health.” In part the research was prompted by the observance in the last decade or so, of more and more calves getting sick later in the finishing period rather than (or in addition to) the receiving period — even calves that were pre conditioned and vaccinated appropri ately. This timeframe is likely related to the overall industry’s focus on car The study involves observing four herds of Angus cross cattle, taking tissue, blood, and serum samples. The researchers are able to assess and monitor the immune phenotype of the calves, beginning at branding, at weaning, both fourteen- and sixty-days post-weaning, and finally twenty-eight days post-feedlot. This way, the calves’ response to stress can be tracked. “The research focuses on whole-ani mal aspects of animal health resulting from current trends in genetic selec tion for growth, milk production, and carcass traits. We aim to determine the effects of the selection of moderate or extreme genetics for weaning and yearling weight, and milk yield in the cow/calf sector on the feed intake, feed efficiency, growth performance, and carcass characteristics of steers; and characterize the stress and immune responsiveness, behavior, and temper ament and thus subsequent robustness to stressors and health challenge.” Dr. Beck says the second objective of the research is to study the impacts of seasonal changes in climate and dietary resources provided to the dam on immunity traits and stress respon siveness of their offspring. They are fortunate to be able to be cass and growth traits. STUDY IN PROGRESS

The Immune system A ccording to a helpful overview article from Oregon State University Extension, the cattle immune system is, “responsible for recognizing, resisting, and eliminating health challenges including pathogens, injuries, parasites, and stress.” Broadly speaking, the immune system is divided into two parts, the innate system and the adaptive system. saliva, and tears, as well as cellular components—primarily white blood cells that kill pathogens and “secrete substances that will further enhance the innate immune response”—and inflammatory response, which is when additional immune cells are recruited to fight infection, when there is increased blood flow to the injury site (swelling) and increased body temperature to kill pathogens (fever). The adaptive immune system mounts a tailored response specific to the pathogen and ‘learns’ so that the next time the same pathogen is detected, it can be attacked even more quickly. This process is also called active immunity. This ‘memory’ feature of active immunity is how vaccines work. Passive immunity is when antibodies are passed from an outside source. This most commonly is exemplified by calves getting protection from pathogens in the environment through colostrum that the mother’s body has already been exposed to and made antibodies for. The immune system is commonly suppressed by stress, including that from extreme temperatures, handling, transport, weaning, and co-mingling. Balanced nutrition, maintaining a regular vaccination schedule, and reducing stress are key to maintaining optimal immune system health. In addition, maintaining clean facilities, checking feed for mold and quality, and quarantining any new animals brought into the herd to reduce the risk of foreign pathogens. Used together, they can improve animal health, productivity, and efficiency. Rethinking management strategies to improve cattle health? Reach out to your veterinarian. And there are many helpful resources available online from extension services across the country. The innate system includes physical barriers, like skin,

able to take a big-picture view of each animal’s health. “Being one of the few universities and researchers with the unique abil ity to watch our animals go from con ception to consumption is extremely valuable when it comes to fitting the puzzle pieces together and sharing the results with producers and research ers,” says Chris Johnson. Johnson is the PhD student in charge of the experiment. “We have also been fortunate to collaborate with many well-respected researchers in a wide range of disciplines. This project has been a big undertaking that has many layers, but as we strive to publish foun dation research to be expanded upon, we hope to begin a new era of BRD research.” There have been some surprising results in the study along the way, in particular the way efficiency relates to growth. “While we’ve found that selection for high growth or high maternal milk pro duction has resulted in heavier animals and larger carcass traits, this does not necessarily translate to more efficiency. Selection for moderate growth results in reduced feed dry matter intake during finishing and improved Residual Feed Intake indicates efficiency improve ments. We have also found that there are seasonal differences in immune function for the calves with differing growth genetics,” Dr. Beck says. “We’re still putting all the pieces together but preliminary results look to show some surprising differences.” Producers can support the cat tle immune system with low-stress handling, maintaining a vaccina tion program, providing adequate nutrition, and regularly doing cattle health assessments. Ultimately, Dr. Beck and his team hope to add to that with a better understanding of robust ness-related traits and useful infor mation for beef producers to consider during trait selection. “Our hope is that the results of this project will provide a foundation for further investigations into the effects of genetic selection for economic traits on animal health and wellbeing and offer a biological basis for alternate selection criteria and genetic-based tools for health and welfare-based selection,” says Dr. Beck.

78 I JANUARY / FEBRUARY 2025 WORKING RANCH audited readers run 21 million head of beef cattle.