By Jamie T. Courter, Ph.D.
Bovine Congestive Heart Failure (BCHF) has become a significant cause of death in feedlot cattle at moderate altitudes (1100 – 5000 ft). Today, mortality from BCHF can reach 7% in severely affected pens of cattle, with extreme economic losses as a result (Heaton and Vander Ley, 2020).
Due to its growing economic impact, extreme focus has been placed on identifying an underlying genetic cause of BCHF. Using matched pairs of BCHF-affected and unaffected pen mates from more than 30 different ranch sources, researchers from the U.S. Meat Animal Research Center tested the bovine genome and discovered two single nucleotide polymorphisms (SNP) found to be more common among BCHF-affected animals (Heaton and Vander Ley, 2020). These two SNPs are believed to be genetic risk factors.
Genetic risk factors are defined as specific sequences of DNA known to play a predictable role in causing disease. However, like diabetes, just because a human has increased risk or susceptibility does not mean they cannot mitigate said risk through diet and exercise. The same can be said for BCHF. Just because an animal has increased risk of being affected with BCHF is not a guarantee of death loss.
Igenity BCHF Reporting
NEOGEN now delivers a commercial solution to directly summarize an animal’s genotype status for the two BCHF risk factors for both the commercial cow-calf and feedlot sectors of the industry in the form of a ‘Breeding Rank’ and ‘Individual Risk Factor’, respectively (Table 1).
Table 1. Translation of BCHF2 and BCHF5 genotype status into Igenity Beef Breeding Rank and Igenity Feeder Individual Risk Factor.
Available with NEOGEN’s replacement heifer profile, Igenity Beef, BCHF Breeding Rank is designed to rank replacement heifers from best (1) to worst (9) based on their likelihood of transmitting risk factor alleles down to progeny.
For terminal animals, however, it is more worthwhile to know if they have an increased likelihood of developing BCHF themselves. Therefore, Igenity Feeder reports BCHF Individual Risk Factor. Animals with an Individual Risk Factor of 15x are 15 times more likely to be diagnosed with BCHF than animals with an Individual Risk Factor of 1x.
For cow-calf producers or feedlot operators experiencing heavy losses of cattle due to BCHF, it may be tempting to use this information as a threshold culling method as if it were a genetic defect. However, BCHF risk factors should instead be reduced through incorporation into existing breeding and management practices.
BCHF for Breeding Decisions
Similar to managing coat color, the frequency of BCHF risk factors can be reduced by planned mating. By selecting animals that have lower breeding rank values, producers affected by BCHF can reduce the disease’s impact on subsequent calf crops. For example, mating a sire with a BCHF Breeding Rank of 2 to a dam with a BCHF Breeding Rank of 9 would result in a reduced BCHF Breeding Rank 100% of the time. However, due to the random assortment of genes, there would be a 50:50 chance the calf would have a BCHF Breeding Rank of 7 or 4 essentially based on which part of the DNA the calf inherited from the sire.
Table 2 provides a simplified explanation of the different Igenity BCHF Breeding Rank values and how they equate to the likelihood of transmitting risk alleles to future progeny.
Table 2. Igenity BCHF Breeding Rank scores and the likelihood of transmitting risk alleles to progeny.
BCHF for Individual Animal Management
Identifying which feedlot cattle have both risk factors may help pinpoint the smallest group of animals that could benefit from alternative management to limit BCHF development. Animals in the 15x or 7.5x group are not guaranteed to become a BCHF case but sorting them into pens may be a way to increase the efficiency of labor to monitor animals for visual cues of BCHF and choose marketing windows appropriate for those groups.
Lastly, knowledge of BCHF risk factor status can also be a marketing tool for feeder cattle with decreased risk.
To learn more about testing for BCHF risk factors, please contact NEOGEN Genomics.
For information about the discovery of BCHF Risk Factors, please visit the USMARC website.
Heaton, M. P., Vander Ley, B. (2020). Genetic risk factor testing for bovine congestive heart failure in feedlot cattle. International Plant and Animal Genome meeting XXVIII. San Diego, CA, USA. https://www.ars.usda.gov/ARSUserFiles/30400500/BCHF_photos/BCHF_Factsheet_03.23.2020.pdf