Detection of Recessive Mutations (BLAD and CVM) in Holstein-Friesian Cattle Population in Republic of Macedonia

BLAD and CVM are Holstein-specific recessive mutations which have had significant economic impact on dairy cattle breeding worldwide. The aim of this study was to optimize a diagnostic test for detection of these two disorders and to obtain a preliminary picture about theire existence in Macedonian HF population. Blood samples were obtained from 84 HF cows from several different farms in Macedonia. Genomic DNA was extracted using DNeasy blood and tissue kit (Qiagen) which was also used for DNA extraction from deeply frozen sperm doses from 6 different HF bulls. Genotyping was performed by PCR-RFLP analysis with TaqI and HaeIII restriction endonucleases for BLAD and with PstI for CVM. The correctness of the genotyping was evaluated by direct sequencing of the amplified products. Among 90 HF cattle tested two cows were identified as carriers of the BLAD allele and one was carrier of the CVM allele. No bulls were found to be carriers of either of the two disorders. This study demonstrates that carriers of BLAD and CVM are present in Macedonia, although at low frequency. PCR followed by RFLP is efficient and inexpensive method for detection of the carriers and should be used as laboratory test in eradication programs. In order to establish a more accurate picture of the prevalence of these disorders, it is necessary to screen a larger number of animals. It is indispensable to test each bull before entering the A.I. program to prevent accidental transmission to a large number of offspring.