Source: Beef Improvement Federation
“This is a real problem in the industry, which is why we are investing so much into developing selection tools we can use to address the problem,” said Justin Buchanan, PhD, of Simplot Land and Livestock. Buchanan gave his talk, “Associations among BCHF, organ phenotypes, scored in the packing plant and treatment records for BRD,” during the 2024 Beef Improvement Federation (BIF) Symposium on June 12 in Knoxville, Tennessee.
Creating traceable phenotypes for heart failure
Simplot’s packing facility, CS Beef Packers, has collected more than 100,000 heart scores since 2020, with 50% showing morphological changes that indicate a progression of BCHF. 4% of the animals with heart scores were classified as score 4 or 5, indicating late-stage heart failure. These scores form the basis of their BCHF EPD.
Findings showed that while BCHF occurs in all breeds, beef breeds had higher concentrations of animals with high heart scores– specifically high percentage Angus – than beef-on-dairy. Notably, a GWAS performed by Gencove did not find the same associations of BCHF with the ARRDC3 or NIFA variants found in other studies. Heritability of heart score was between 0.3 and 0.4, leading Buchanan to believe BCHF is a polygenic trait that selective breeding decisions can influence.
Other findings were that hot carcass weight was the most associated trait with BCHF at 0.4. Buchanan said, “When we use our selection indexes to drive carcass weight and growth, we are pulling those congestive heart failure cases right along with that selection. So, if we don’t create a tool to select against this, it’s just going to get worse over time”.
Within Simplot’s purebred herds, the mean EPD values for heart score were 0.102 for Angus, -0.037 for Charolais, and Herefords with -0.003.
Traits of lung deflation score and BRD treatment records were included in the selection model to increase accuracy. Lungs failing to deflate post-harvest indicate fibrosis, and higher heart scores from this cohort were correlated with increased pathology and lungs that failed to deflate. BRD was also included via a score based on the number of treatments in the feedlot.
Regarding genetic parameter estimates, the heritabilities of BRD, BCHF, and lung deflation were calculated at 0.14-0.12, 0.29, and 0.27, respectively. Buchanan proposed that the correlation of 0.9 between lung deflation and BCHF shows they may be indicator traits for one another.
Next steps in developing a BCHF EPD
“The next steps for our program are to make multi-trait genetic evaluations. That’s always something we are trying to do,” explained Buchanan in his wrap-up. This multi-trait model would be used to start a total health model. Economic weights for BRD and BCHF would be included, as well as histopathology findings from Kansas State University College of Veterinary Medicine.
For this population, there is a genetic correlation between the PAP score and heart score of only 0.2, indicating that PAP may be a sign of cardiopulmonary abnormalities at altitude, but not a useful indicator of heart health in the feedlot. The two-marker test from USMARC also showed a false positive rate of 77%. Buchanan emphasized that the most practical tools for managing BCHF include stress management, crossbreeding, and utilization of selection tools. One such selection tool mentioned was the Simplot BCHF EPD itself, which is included in the Igenity Beef panel from NEOGEN. Buchanan pointed out that it is the most accurate model currently available and will be updated annually with improvements.
To watch Dr. Buchanan’s full presentation, visit https://www.youtube.com/watch?v=EN5qF6pUUfI&t=1193s. For more information about this year’s Symposium and the Beef Improvement Federation, including additional presentations and award winners, visit BIFSymposium.com.
