Bioavailability of iron in growing rabbits fed excess levels of dietary iron, under Egyptian conditions.

Five levels of dietary iron (Fe), 215, 290, 365, 415 and 515mg/kg were fed for 56 days to five groups of growing New Zealand White rabbits (average initial body weight 728g) each of 14 rabbits (7 males and 7 females) to investigate Fe bioavailability and determine the maximum safe level of dietary iron, under Egyptian conditions. Ferrous sulfate (FeSO4 2H(2)O) was used as the supplemental Fe source. The results of the present study indicated that viability of rabbits (\%) daily feed intake, NFE digestibility, haemoglobin and blood serum contents of total lipids, calcium, magnesium and iron were not affected significantly by the dietary iron treatments. Increasing the dietary iron above 290mg/kg decreased (P<0.01 or 0.05) the final live body weight. daily body gain, feed conversion efficiency, DM, OM, CP, CF, EE digestibilities, N-utilization and blood serum concentrations of phosphorus, glucose and total protein. Levels of serum GOT and GTP enzymes were increased (P<0.05 and 0.01, respectively) with increasing the dietary iron level. No clinical signs of iron toxicity were observed in rabbits of any dietary group throughout the experimental period. Gross and microscopical examination did not reveal any significant alteration in liver, spleen, kidneys and lungs of rabbits given the dietary iron levels up to 365mg/kg. Mild to moderate degenerative hyperplastic, emphysema and proliferating changes were observed in the indicated organs of rabbits fed the dietary iron levels 415 or 515mg/kg.