Chemical analysis
Crude protein and crude fibre of the experimental diets were carried out using the methods of AOAC (2000). Broken egg shells were rinsed in water, air dried and ground with pestle and mortal. Eight shell samples per treatment were digested by dry ash-procedure at 6000C for 6 hours to estimate eggshell ash. Furthermore, 8 egg shell samples per treatment were digested by wet-ash procedure using perchloric acid and nitric acid. Phosphorus concentration was determined colorimetrically (Genesys 5 Spectrophotmer; Thermo Electron Corporation, Madison, WI) at 410nm according to AOAC (1995) methods.