Weaning is a considerable challenge to the young piglet and represents the beginning of a critical period in its life. It is also the period which has a significant effect upon both short- and long-term growth and development. Rapid early growth results in higher and more efficient growth in the subsequent growing and finishing periods. Indeed, it is a common commercial experience that the ability to produce quality lean carcases from fast-growing modern genotypes is enhanced by rapid post-weaning growth. The objective of the current trial was to measure the performance and growth potential of modern pig genotypes in the 5-week post-weaning period, when offered non-limiting diets under commercial conditions.