Bovine Lymphocyte Intestinal Retention Deficiency – detection of causal mutation among Holstein-Friesian bulls using the PCR-RFLP technique

The aim of this study was to develop a PCR-RFLP diagnostic test to detect the causal mutation for Bovine Lymphocyte Intestinal Retention Deficiency (BLIRD). A total of 217 bulls were tested, including 112 bulls being sons of a known BLIRD-carrier sire and 105 bulls used in insemination from 2020 - 2024 with no indication of BLIRD in their pedigree data. Genomic DNA was isolated from the commercial semen straw. The method developed for identifying the causative BLIRD mutation involved PCR amplification of a 412 base pair fragment of the ITGB7 gene and its digestion with the restriction enzyme Ssi I, which allowed for the clear and cost-effective genotyping of BLIRD. In the first group of 112 bulls, 60 BLIRD carriers and 2 BLIRD-affected bulls were identified. They were sons of internationally known top sires, Manfred (US2183007), Convincer (US2249055) and Justice (US22358313). In the second group of 105 bulls, 7 BLIRD carriers were found, giving a frequency of 6.67% among bulls born within the last five years. Further research should be conducted on a larger number of bulls, particularly those for which there is a risk of carrier status based on the bull's pedigree.