Synthetic lysine and fat supplements are widely used in diets for growing pigs. However, there is evidence to suggest that free lysine is more rapidly absorbed than protein bound amino acids resulting in reduced growth performance particularly under infrequent feeding regimes. In addition, the incorporation of conventional fat supplements into cereal based diets is problematic particularly where on-farm mixing of feed is carried out. One potential solution to both these problems is to use fat coated synthetic lysine sources which have recently become available and two such materials were evaluated in this study.

Four dietary treatments were compared. These were a control diet (C) with soya bean meal as the protein supplement and diets in which 0.3 of the total lysine was supplied from either synthetic lysine (S) or synthetic lysine coated with a single (SC) or a double layer(DC) of hardened soya oil. All diets were barley based and were formulated to contain the same level of total lysine (0.01) and hardened soya oil.