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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Genomics and Improvement Laboratory » Research » Publications at this Location » Publication #419021
Research Project: Increasing Accuracy of Genomic Prediction, Developing Algorithms, Selecting Markers, and Evaluating New Traits to Improve Dairy Cattle

Location: Animal Genomics and Improvement Laboratory

Title: Inheritance of BLIRD disorder affects Holstein production performance

Author
item Al-Khudhair, Ahmed
item Null, Daniel
item Van Raden, Paul
item NICOLAZZI, EZEQUIEL - Council On Dairy Cattle Breeding

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: A recessive disorder (BLIRD) affecting heifer survival and cow performance was discovered recently in France. The inherited marker occurred within a prevalent haplotype in US Holsteins. Our study used pedigree to track the unmutated haplotype present in many popular sires of the Holstein breed and the mutated haplotype version inherited from the earliest carriers. Homozygous calves who inherited the mutated haplotype from both parents had poorer performance in US data than estimated in France. Identifying and tracking the BLIRD disorder is difficult without using a direct gene test to implement proper breeding management and avoid welfare loss associated with such diseases.

Technical Abstract: Improved methods previously developed for tracking new mutations within existing haplotypes for cholesterol deficiency (HCD) and muscle weakness (HMW) now also were applied to track the bovine lymphocyte intestinal retention defect (BLIRD) discovered in France. Gene tests were available in U.S. data for HCD and HMW but not yet for BLIRD. Haplotype status for 3 million genotyped animals that also had U.S. phenotypes were used to compare recessive effects of BLIRD homozygotes with French estimates. Heifer livability was 97.6% for normal calves with no copies of the haplotype (code 0) but averaged 88.8% for 178 homozygotes (code 2) and 94.1% for 2,029 uncertain homozygotes (code 4) with corresponding estimates of -8.6% and -3.3% from an animal model. Haplotype carriers verified by pedigree (code 1) or uncertain carriers (code 3) were not affected. Yield trait effects for 412 code 2 homozygotes were -1,799 kg milk, -63 kg fat, and -55 kg protein with a cost of -$1,206 using lifetime net merit values; other traits not yet studied may increase that cost. Mating a BLIRD carrier randomly to a population with 8.9% allele frequency would cause an economic loss of $1,206 * 0.089 / 2 = $54 because half of the progeny would inherit the carrier’s normal allele. Those losses should already be reflected in evaluations which average the merit across normal, carrier, and homozygous daughters. Genomic predictions do not fully track those losses because new mutations are poorly correlated with nearby markers. However, U.S. adjustments for future inbreeding automatically reduce evaluations of popular ancestors by more than the cost of these individual defects. Gene tests are needed for new mutations within common haplotypes because tracking can be difficult even with accurate pedigrees.