At Iowa State University, purebred Yorkshire pigs have been divergently selected for increased and decreased feed efficiency based on residual feed intake for ten generations. In this study, juvenile IGF-I serum concentrations were measured in these divergently selected lines, with the goal of validating juvenile IGF-I as an early blood bio-marker to help select young piglets for later feed efficiency performance.

Previous findings (Bunter et al., 2002, 2005, 2010) and this validation study support that lower juvenile IGF-I concentration in piglets is genetically correlated with increased grow-finish feed efficiency. IGF-I concentration is a moderately heritable trait that is more cost and time effective to measure than feed intake and feed efficiency. These characteristics make IGF-I a useful bio-marker for feed efficiency in swine.