Oligonucleic acid molecules comprising a SNP site at a position corresponding to position 7480 of the bovine signal transducer and activator of transcription (STAT5A) coding sequence (SEQ ID NO: 1). Also disclosed are an array or a kit comprising the same, a method for detecting the SNPs, a method for progeny testing of mammals, a method for increasing human and non-human mammal pregnancy rate in natural and artificial reproduction processes. Further provided are cattle breeding methods for improved milk production traits.
