James et al. (2002c,d) observed that pigs reared in a commercial facility and fed diets containing 50 mg/kg L-carnitine during the last 3 to 4 wk before slaughter had improved growth performance, which was in contrast to a number of studies where L-carnitine did not affect ADG of growing-finishing pigs (Smith et al., 1996; Owen et al.,
2001a,b).