Myostatin mutation causing double muscling could affect increased psoroptic mange sensitivity in dual purpose Belgian Blue cattle

•Psoroptic mange sensitivity is associated with MSTN in dual purpose Belgian Blue.•Mange sensitivity was assessed by scoring lesions by size and severity.•The nt821(del11) mutation is known for causing double muscling in Belgian Blue.•Animals with the nt821(del11) mutation have larger lesions.•This association links the lack of MSTN to ectoparasitic susceptibility.