Chromosomal distribution of cattle OR genes. Cattle OR genes were mapped to 49 regions across 26 chromosomes. The number of functional and pseudo OR genes at each cluster is indicated to the right of the chromosomes without and with parentheses, respectively. Clusters with and without functional OR genes are indicated by black and red lines, respectively. The position of each cluster is shown to the left of the chromosomes in Mb. Cluster naming scheme A-B: A, chromosome name and B, distance (Mb) from the top of that chromosome. “U” indicates a group of sequences with no chromosome assignment in the cattle genome assembly UMD3.1. Chromosome figures were modified from .