Morbidity in high-performing cattle studied

During the virtual Sept. 8 Cattle U hosted by High Plains Journal, Dr. Miles Theurer, research director for Veterinary Research and Consulting Services, LLC, discussed research looking at issues during the mid-feeding period with bovine respiratory disease (BRD) morbidity in high-performing cattle. 

            “We have seen an increase of BRD in cattle during late days on feed,” he stated. “However, there have been no formal studies conducted to evaluate the potential causes of morbidity in higher-performing cattle.” 

            Therefore, Theurer and a team of researchers set out to do just that.

The BRD complex

            To begin, Theurer noted it is important to first understand the BRD complex, which consists of three components contributing to the disease. 

            “First, there is the host, which includes age, immunity and nutrition,” he explained. “Second is the environment, which includes animal density, animal mixing, weather, pen conditions and human interaction.”

            According to Theurer, the pathogen is the third component. He noted this may include a primary viral infection including bovine herpesvirus type one, parainfluenza3, bovine respiratory syncytial virus or bovine viral diarrhea, as well as a secondary bacterial infection, including Mannheimia haemolytica, Pasteurella multocida, Haemophilus somnus and Mycobacterium bovis. 

            “If any one of these three components swings out of balance, the opportunity for disease may occur,” Theurer stated. 

Temporal BRD patterns 

            One of the first things Theurer and his team looked at were retrospective temporal BRD patterns in high performing versus high-risk populations. Data was collected at the Hy-Plains Feedyard, LLC in Montezuma, Kan. 

            “The high-risk calves were chosen based off of a risk assessment and were administered metaphylaxis,” Theurer noted. “The high-performing cattle were categorized as the top 25 percent for average daily gain, feed conversion and quality grade.” 

            Theurer explained high-performing calves began breaking with respiratory disease around day four.

            “By this time, the bulk of calves in the high-risk group had already broke with disease, so the high-performing cattle seemed to be breaking at a later time,” he stated.

Repeatability of health outcomes

            Additionally, Theurer and his research team collaborated with the Noble Research Institute through the International Consortium for Antimicrobial Stewardship in Agriculture Program to look at the repeatability of health outcomes. 

            “To do this, we did a retrospective analysis from data the institute had put together on 4,346 calves they followed throughout the supply chain,” Theurer explained. “These cattle were spring calved, fall weaned and preconditioned for 60 days or more. They also received two rounds of blackleg vaccine and a viral respiratory disease vaccine, one round for shipping fever and they were dehorned, castrated and wormed.” 

            When looking at the cumulative morbidity risk in this set of calves, Theurer explained most cases occurred earlier in the feeding period. However, after day four, they still had one-third of calves breaking with BRD. 

            “We repeated the study in a different feedyard in Texas with 1,012 yearlings and saw very similar results,” he said. “This leaves us wondering if the morbidity we are seeing is more related to transportation stress and adaptation to the feedyard or if there is a completely different underlying issue. We also want to know how we can better manage and prevent BRD in the future.”

Health outcomes by cow/calf operation

            Another set of data analyzed by Theurer looked at health outcomes of calves based on the vaccine protocol they underwent on the cow/calf operation.

            “We wanted to look at what is being done to those calves prior to arrival at the feedyard that either sets them up for success or failure,” he said. “Therefore, we looked at the date of the first BRD treatment in the feedyard compared to how many modified live vaccines (MLVs) the calves were given prior to arrival.”

            “We found calves given only one MLV prior to coming to the feedyard actually had a lower first treatment compared to calves given three vaccines,” Theurer continued. “I am not saying vaccines aren’t helpful, however more may not necessarily be better.”

Effect of rate of gain and backgrounding

            The last study Theurer and his team put together analyzed the effects of rate of gain and backgrounding on the incidence of BRD at the feedlot. 

            “With help from the Noble Research Institute, we put together two groups of small calves, with 56 head per group. We looked at different randomizations over preconditioning for 80 days versus 197 days before they came to the feedyard,” Theurer explained, noting the goal of the study was to understand which management strategies prior to cattle entering the feedlot would set them up for success.

            “Cattle preconditioned for 197 days had nine percent cumulative morbidity and all but one of these cases occurred after 30 days on feed,” Theurer noted. “My hypothesis is these calves might be subclinical, and we don’t see signs of sickness until later in the feeding period.”

He continued, “At this point, we don’t have an exact answer, but we now have a lot of the right information to start understanding how to fix this problem.”

            “Unfortunately, morbidity and mortality in high-performing cattle is greater than expected and generally occurs at later days on feed compared to high-risk calves,” he concluded. “Additional research is needed to further evaluate the potential cause and effect of mid-feeding period morbidity and late-day mortality, and to do this, the beef industry needs to continue working together to better understand issues up and down the supply chain.” 

            Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.