Responses of young chicks to amino acid supplementation of methanol-grown dried microbial cells

Two experiments have been conducted to examine the effects on chick growth and carcass composition of amino acid additions to diets containing spray-dried or flash-dried forms of methanol-grown microbial cells (S-DMC and F-DMC respectively). The spray-dried form was an early development product. An additional factor was the level of total nitrogen (N) in control diets containing soyabean (SBM) and in experimental diets containing 100 g S-DMC or 150 g F-DMC kg^?1 diet. In the first experiment, a diet containing S-DMC supported less growth than the control SBM diet containing equivalent concentrations of total N (39 g kg^?1 DM) and of the sulphur containing amino acids. Supplementation of S-DMC diets containing 36 and 32 g N kg^?1 DM with methionine had no substantial effect on growth or on carcass composition. In the second experiment, methionine supplemented SBM and F-DMC diets containing 43 g N kg^?1 DM elicited similar growth performance and efficiency of food conversion. However, the feeding of basal SBM and F-DMC diets containing sub-optimal concentrations of total N (35 and 36 g N kg^?1 DM respectively) resulted in inferior utilisation of the F-DMC diet, this effect being only partially alleviated by combined dietary supplements of arginine, lysine and methionine.