Double muscling is a hereditary genetic syndrome affecting cattle, and is most notably characterised by the extreme hypertrophy of muscles, occurring in most breeds of cattle. While the double-muscled phenotype has the benefit of increased yield over the hook with a larger percentage of higher priced cuts, it is also associated with reproductive issues. The relationship between double muscling and calving ease has been well documented, with a general consensus that the homozygous affected - genotype - with two mutated myostatin alleles - is unfavourable for calving ease and birth weight compared to heterozygous and normal contemporaries. Calving difficulty in double muscled cattle is related to a morphological imbalance between the dam and calf at time of birth, where the calf width and weight is increased in homozygous affected calves, or a decrease in the pelvic area of the dam, or both depending on the mating. Carriers of the double-muscling gene are not significantly different for calving ease compared to normal cattle, but performed significantly better for post-birth production traits. For commercial beef production these findings indicate the usefulness of genomic testing for the identification of individuals with double-muscling alleles, allowing mating schemes to be built to maximise production of heterozygous animals to benefit from improved yield and avoid reproductive disadvantage.