Interactions were not evident between prenatal and pre weaning growth for subsequent growth, efficiency, carcass,yield and beef-quality characteristics, within our pasturebased production systems. Interactions between genotype and nutrition early in life studied using offspring of Piedmontese (a high muscling, higher birth weight breed,homozygous for a mutation that produces non-functional myostatin) and Wagyu (a high marbling, lower birth weight breed) sires mated to Hereford cows were not evident for any growth, efficiency, carcass, yield and beef-quality parameters.