the following online material is available for this article : table s1 - primer sequences used to analyse bovine th and dbh genes .
dna from four cattle breeds was used to re - sequence all of the exons and 56% of the introns of the bovine tyrosine hydroxylase ( th ) gene and 97% and 13% of the bovine dopamine -hydroxylase ( dbh ) coding and non - coding sequences , respectively . 
 two novel single nucleotide polymorphisms ( snps ) and a microsatellite motif were found in the th sequences . 
 the dbh sequences contained 62 nucleotide changes , including eight non - synonymous snps ( nssnps ) that are of particular interest because they may alter protein function and therefore affect the phenotype . 
 these dbh nssnps resulted in amino acid substitutions that were predicted to destabilize the protein structure . 
 six snps ( one from th and five from dbh non - synonymous snps ) were genotyped in 140 animals ; all of them were polymorphic and had a minor allele frequency of > 9% . 
 there were significant differences in the intra- and inter - population haplotype distributions . 
 the haplotype differences between brahman cattle and the three b. t. taurus breeds ( charolais , holstein and lidia ) were interesting from a behavioural point of view because of the differences in temperament between these breeds .