Possible Causes and Consequences of the Distribution of Separate Allelic Variants of the LEP Gene in the Groups of Ayrshire and Holstein Cattle

Abstract

PCR/RFLP technology was implemented to identify genotypes for the Y7F, A80V, R25C loci of the leptin gene in 912 cattle of Holstein and Ayrshire breeds. This analysis revealed polymorphism for SNP allele Y7F (A → T substitution at Y7F site at position 95 689 996 bp in LEP gene), which is practically absent in Holstein animals (n = 410), where the frequency of occurrence of allele F is 0.01. In contrast, in the Ayrshire animal group (n = 502), Y7F SNP polymorphism is common, with the frequency of the occurrence of allele F at 0.25, while A80V SNP allele polymorphism for this gene (C → T substitution at the position 95 691 973 bp of the leptin gene) was not detected. In Ayrshire cattle, the FF genotype (at the Y7F site) was detected only in combination with the RRAA genotype (T → C substitution at the R25C site at position 95 690 050 bp in the LEP gene) in 100% of all possible combinations of genotypes (FFCCAA, FFRCAA and FFRRAA). In addition, genotype VV (site A80V) was detected in Holstein cattle in combination with the YYCC genotype (Y7F, R25C sites) in 100% of all possible combinations of the genotypes (YYRCVV, YYRRVV, YYCCVV). We also found that Ayrshire cattle displaying RR genotype at the LEP R25C locus are more likely to have a longer productive life than animals with other genotypes (in particular, with the CC genotype at the R25C locus). Taken together, we conclude that A80V polymorphism affects the predicted transmitted ability for milk production (PTAM), the fertility index of daughters (FI), and the pregnancy rate of daughters in Holstein cattle (DPR).