Use of industrial amino acids to allow low protein concentrations in finishing diets for growing Muscovy ducks

1. Three experiments were performed to assess the effects of decreasing protein concentration in the finishing diets for growing Muscovy ducks (8 to 12 weeks of age) by adding 4 essential amino acids (AAs, lysine, methionine, threonine and tryptophan). Experimental diets with crude protein (CP) contents from 105 to 142 g/kg, were compared with control diets providing 150 to 160 g/kg CP. In each trial, all diets were isocaloric. No significant modification in growth or carcase quality was observed when CP was greater than 124 g/kg in diets supplemented with the 4 essential AAs. 2. There was no advantage in supplying more than 4.3 g of digestible lysine per kg of diet (12.75 MJ ME/kg). When threonine was not added, breast yield decreased significantly (-4.3%), while omitting tryptophan supplementation did not influence performance. 3. Furthermore, the experiments confirmed that reducing CP had little or no effect on food conversion efficiency and fatness in Muscovy ducklings, unlike the observed situation in broiler chickens.