In this study, it was aimed to investigate the relationship between three SNP on the BRCA1 gene and subclinical mastitis, as well as milk yields during four lactation periods in Holstein breed cattle. The animal material of the study consisted of 151 Holstein cows reared under the same care and feeding conditions. Complete DNA was isolated from blood samples by using phenol: chloroform: isoamyl alcohol method. Genotyping of G22231T, T25025A and C28300A SNPs on the BRCA1 was done by the PCR-RFLP method. Subclinical mastitis of animals was determined in milk samples by California Mastitis Test (CMT). In the study, CMT data, four lactation periods' milk yields, and proportional distributions of SNP genotypes were calculated. Statistical significance of the data was determined by the Pearson chi-square test. The relationship between C28300A SNP, which was monomorphic, and subclinical mastitis has not been analyzed. In the samples examined, the difference between the proportional distribution of SNP genotypes of G22231T and T25025A in subclinical mastitis and healthy groups was not found statistically significant (P>0.05). As a result of the Chi-square (χ2) analysis conducted, it was observed that the Holstein cattle were in the Hardy-Weinberg equilibrium in terms of G22231T and T25025A SNPs. Considering the physiological processes in which the BRCA1 gene is involved, it was thought that these genes and SNPs should be evaluated with more samples in studies on resistance to mastitis.

Özet: Bu çalışmada Türkiye'deki Holştayn melezlerinde Sığır Lökosit Bağlanma Eksikliği (BLAD) ve Faktör XI Eksikliği (FXID) kalıtsal hastalıklarına sebep olan mutant allellerin varlığının araştırılması amaçlanmıştır. Çalışmada toplam 48 baş sığır incelenmiştir. Yapılan moleküler analizlerden sonra incelenen melez sığırların birinin BLAD taşıyıcısı olduğu, FXID taşıyıcısı bireye rastlanılmadığı görülmüştür. Bu çalışma ile bu kalıtsal hastalıkların görüldüğü saf Holştayn ırkı dışında da BLAD ve FXID'ne sebep olan mutant allellerin varlığı araştırılmıştır. Böylece saf Holştayn ırkının haricinde de BLAD'a sebep olan mutant allelin varlığı ilk kez gösterilmiştir. Çalışma sonunda özellikle ıslah ve çevirme melezlemelerinde baba hat olarak kullanılacak damızlıkların, önemli kalıtsal hastalıklardan ari olduklarının kontrol edilmesi gerektiği sonucuna varılmıştır. Eğer bu konuda gerekli özen gösterilmez ise daha önce ırka özgü olduğu bilinen kalıtsal hastalıklara (BLAD, FIXID vb.) sebep olan mutant allellerin diğer sığır ırklarına da yayılabileceği sonucuna varılmıştır. Anahtar kelimeler: BLAD, FXID, Holştayn melezi, kalıtsal hastalık, sığır Investigation of FXID and BLAD Diseases in Holstein Crossbreed Cattles Reared in TurkeySummary: This study aimed to investigate the presence of mutant alleles of Bovine Leukocyte Binding Deficiency (BLAD) and Factor XI Deficiency (FXID) hereditary diseases in Holstein crossbreeds reared in Turkey. Total of 48 cattle were examined in the study. After molecular analysis, it was observed that one of the crossbreed cattle examined was a BLAD carrier and no FXID carrier was found. With this study, the presence of mutant alleles that cause BLAD and FXID, except for the purebred Holstein in which these hereditary diseases are seen, was investigated. So, It was determined for the first time that the presence of mutant allele was also seen in crossbreed Holstein. At the end of the study, it was concluded that breeds to be used as sire lines in breeding and crossbreeding should be checked which they had free from important hereditary diseases. It is concluded that mutant alleles that cause hereditary diseases (BLAD, FIXID, etc.), which were previously known to be breed-specific, can spread to other cattle breeds if the necessary care is not taken.