The response of broilers to dietary digestible lysine levels In the starter phase
Adequate dietary lysine supply is crucial for the optimal performance of broiler chickens. In most published research total lysine value is used for diet formulation. It has been demonstrated that the performance of broilers fed diets formulated using digestible amino acid values was superior to that of birds fed diets formulated using total amino acid values.
The current study was to determine the optimal dietary digestible lysine level for production performance. Day-old male Ross chicks and semi-purified diets with added synthetic amino acids were used in this study. All dietary digestible amino acids concentrations were based on the ideal amino acid concept (Baker, 1997) except lysine which was formulated at 6, 8, 10, 12 and 14 g/kg diet, respectively.
Chicks were weighed, wing tagged and allocated to five dietary treatments with five replicates of seven birds in each diet. Individual body weight and pen feed intake were recorded weekly and feed efficiency was calculated.
Birds body weights were significantly increased from 378g to 812g (p<0.0001) at day 21 when dietary digestible lysine content was increased from 6g to 12g/kg. Feed intake from day 1 to 21 was also significantly increased (p<0.001) as the lysine content increased from 6g to 10g/kg. Feed conversion rates were substantially reduced from 2.06 to 1.41 (p<0.0001) when lysine content increased to 12g/kg.
No beneficial effects were observed on production performance with further increase of lysine content to 14g/kg. The results from this study suggest that for optimal performance of broiler chicken during the starter phase, dietary digestible lysine content of 12g/kg is adequate.
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Article made possible through the contribution of the Australian Poultry Science Symposium (APSS) 2006.