Haplotype HH6: identification of carriers in holstein cattle

The article presents the results of monitoring the prevalence of the HH6 fertility haplotypes, a lethal recessive genetic defect relevant to modern Holstein cattle breeding. The study was conducted on a sample of 194 animals (94 bulls and 100 cows) selected from three leading breeding enterprises in the Russian Federation. Genotyping was performed using a combination of PCRRFLP and real-time PCR methods aimed at detecting a point mutation (g.29020700 A>G) in the SDE2gene (telomere maintenance homolog). The PCR-RFLP method involved the amplification of a 524 bp gene fragment, followed by analysis of restriction-patterns. To validate the results, real-time PCR was performed using the commercial reagent kit «HH6-RT-100» (VetGenomika LLC, Novosibirsk). The analysis identified one carrier bull of the HH6 mutation among the 94 bulls tested, corresponding to a carrier frequency of 1.1%. No carrier cows were detected. The obtained data underscore the importance of continued systematic screening to control the spread of the HH6 haplotype. The developed PCR-RFLP methodology proved to be reliable and is recommended for implementation in the practice of breeding farms and laboratories engaged in genomic selection. The implementation of DNA testing will prevent inbred matings and minimize economic losses associated with embryonic mortality, thereby contributing to the improvement of breeding and selection programs in dairy cattle farming.

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