Previous investigations have shown lamb vigour to be improved by including long chain omega-3 fatty acids in maternal diets during late pregnancy (Capper et al., 2003; Dawson and Edgar 2005; Pickard et al., 2005). However, these trials fail to elucidate whether there is a period in late gestation when supplementing diets with omega-3s would be optimal. Omega-3 fatty acids, particularly docosahexaenoic acid (DHA), are found in high concentrations in brain and nervous tissue (Arbuckle and Innis, 1993), and are therefore required at times of neural and brain tissue growth. This study explored the effects of feeding an algal source of EFAs, with a high content of DHA, during different time periods on measures of lamb viability.