Comparison of endogenous amino acid flow in broilers, laying hens and caecectomised roosters

1. This study was conducted to determine and compare endogenous amino acid (EAA) flow in broilers, laying hens, and caecectomised roosters fed on either a nitrogen-free diet (NFD) or a highly digestible protein diet (HDP). 2. Also, the EAA flows using three methods (fasted, NFD, or HDP) in precision-fed caecectomised roosters were compared. 3. EAA flow did not differ between broilers and laying hens on either the NFD or HDP diets. 4. Endogenous amino acid flow in caecectomised roosters was 3.5-12-fold higher than for broilers and laying hens for both methods (NFD and HDP) of estimation. 5. When caecectomised roosters were fasted or precision-fed (NFD or HDP), there was no difference in EAA flow between the NFD- or HDP-fed birds. 6. However, flows from fasted roosters were lower than from roosters receiving either the NFD or HDP diet. 7. Results from this study showed that EAA flow is method-dependent. Total amino acid flow from fasted birds was 31% less than when a NFD was fed to caecectomised roosters.