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Summary Seven sequence variants (SVs) have been identified in exon 1 and in the promoter region upstream of the bovine gonadotrophin releasing hormone (GnRH) receptor gene, at nucleotides g.−331A>G, g.−108T>C, g.+206G>A, g.+260C>T, g.+341C>T, g.+383C>T and g.+410C>T relative to the translation start site. The SVs at nucleotides g.−108, g.260, g.341 and g.410 and those at g.206 and g.383 formed two groups with complete linkage disequilibrium within groups, but incomplete linkage disequilibrium between groups, and none of the SVs altered receptor amino acid sequence. The g.−108T>C allelic variants were associated with an approximately 0.4 day reduction in predicted transmitting ability for days to first service. None of the allelic variants affected the pattern of circulating LH following administration of GnRH. The g.260C>T alteration introduced a new transcription factor binding site in a region of DNA with relatively low nucleosome formation potential. The data suggest that selection for animals carrying the g.-108T>C group of alterations will improve fertility in the dairy cow.

Summary Mutations within a number of genes have been associated with variations in fertility in various mammals. However, to date there have been no such associations reported for cattle. Herein, we describe three single nucleotide polymorphisms (SNPs) in the luteinizing hormone/choriogonadotropin receptor gene of cattle (Bos taurus). These polymorphisms include two missense mutations and one sense mutation, and all are located in areas of conserved synteny. When assessed in terms of haplotypes, these SNPs were significantly associated with variations in cattle fertility and production traits, most notably on calving interval, days to first service and production index (the UK economic index of milk yield measured in £GB).