Abstract: The novel means by which an efficiency of ovum collection can be easily determined in bovine at gene level is disclosed. The present inventors performed the genomic linkage analysis using bovine populations with high and low efficiency of ovum collection and to identify GRIA1 gene, which encodes an ion channel protein, as a factor deeply related to an efficiency of ovum collection. Bovines having a mutation (e.g. the amino acid substitution of aa306) in GRIA1 produce significantly fewer ova on superovulatory treatment than those not having the mutation. Therefore, the efficiency of ovum collection can be determined based on the existence of a mutation in GRIA1 gene.