“…The mutations or indels of MSTN have been shown to produce a double-muscling phenotype caused by muscular hyperplasia and hypertrophy in some of livestock species, such as cattle breeds (Belgian Blue, Piedmontese) (Grobet et al, 1997;McPherron and Lee, 1997;Kambadur et al, 1997;Miranda et al, 2002) and sheep (Texel sheep, East Friesian sheep) (Walling et al, 2004;Johnson et al, 2005;Clop et al, 2006;Bignell et al, 2010) and chickens (Gu et al, 2002 Furthermore, double-muscling is an autosomal recessive gene that can be inherited and it is occurred due to abnormal growth of muscles (Khaerunnis et al, 2016). A single nucleotide variation in intron region of the MSTN gene (g.66493737T>C) is using as a molecular marker for the breeding parameter such as race distance ability in horses and many morphological characters in livestock (Binns et al, 2010;Tozaki et al, 2010;2011;Hill et al, 2010a;2010b;2012a;2012b;Dall'Olio et al, 2010;Stefaniuk et al, 2014;Pereira et al, 2016;Işık et al, 2017;Tüten sevim et al, 2017;Cieslak et al, 2018). Many studies have been carried out MSTN gene polymorphisms in horses and its association with racing performances and body condition but in donkeys, there were a few published articles till now (Bertolini et al, 2015;Tozaki et al, 2010;2011;Hill et al, 2010a;2010b;2012a;2012b;Dall'Olio et al, 2010;Stefaniuk et al, 2014;Pereira et al, 2016;Cieslak et al, 2018;Dong-hua et al, 2017).…”