where IEL was basal endogenous losses of AA; AID ¼ apparent ileal digestibility; SID ¼ standardized ileal digestibility Crd was Cr concentration in diets Cri was Cr concentration in ileal digesta AAd was AA concentration in diets and AAi was AA output in ileal digesta. All values used were expressed as milligrams per kilogram of DM, except the IEL was expressed as milligrams per kilogram of DMI