caa a22 4500 397567006 CHVBK 20180308164830.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.3382/ps.0750495 doi (NATIONALLICENCE)oxford-10.3382/ps.0750495 Effect of Dietary Iron Concentration, Age, and Length of Iron Feeding on Feed Intake and Tissue Iron Concentration of Broiler Chicks for Use as a Bioassay of Supplemental Iron Sources [Elektronische Daten] [J. CAO, X. G. LUO, P. R. HENRY, C. B. AMMERMAN, R. C. LITTELL, R. D. MILES] Three experiments were conducted with day-old chicks to study the effects of dietary Fe concentration and age on Fe accumulation in tissues as an estimate of supplemental Fe bioavailability, and of delaying the time of initial high Fe supplementation up to 7 d of age on feed intake to 3 wk of age. In Experiment 1, chicks were fed a basal corn-soybean meal diet (188 mg/kg Fe, DM basis) or the basal supplemented with 400, 600, or 800 mg/kg added Fe as reagent grade FeSO4·7H2O for either 1, 2, or 3 wk. Dietary Fe depressed (P < 0.001) feed intake and body weight gain, especially at 3 wk. Kidney Fe concentrations increased linearly (P < 0.001) with increasing dietary Fe. Liver Fe concentration also increased linearly, but reached a plateau in birds fed 600 mg/kg Fe. Bone Fe increased linearly (P < 0.05) at 1 wk, but not at 2 or 3 wk. Liver and kidney Fe regressed on daily Fe intake had the best fit to a linear model at 2 wk. In Experiment 2, chicks were fed either a basal diet (320 mg/kg Fe, DM basis) continuously, the basal supplemented with 800 mg/kg added Fe as FeSO4·7H2O continuously, or were started on the control diet and switched to the high Fe diet on Day 3, 5, or 7. Feed intake was lower (P < 0.05) in birds started on Fe on Days 1 or 3, but delaying feeding of high Fe diets until Day 5 resulted in intake at 3 wk similar to that of birds fed the basal diet. In Experiment 3, the basal diet (123 mg/kg Fe) was fed to chicks for 6 d, then experimental diets were fed for 14 d. Diets were the basal or basal supplemented with 400, 600, or 800 mg/kg added Fe as reagent grade or feed grade Fe sulfate or an Fe methionine complex. When estimated from regression of log10 liver Fe concentration on total analyzed dietary Fe concentration, relative bioavailability was set at 100% for reagent grade Fe sulfate, and the feed grade sulfate was 92.3% and Fe methionine was 88.3%. Liver Fe concentrations may be useful criteria for determining Fe bioavailability and 2 wk of feeding was the optimal time required for such a bioassay. Delaying feeding high Fe diets until 5 d of age alleviated the decreased feed intake associated with high Fe diets. © 1996 Poultry Science Association, Inc. Metabolism and Nutrition nationallicence iron nationallicence age nationallicence feed intake nationallicence bioavailability nationallicence chick nationallicence CAO J. Departments of Animal Science, aut LUO X. G. Departments of Animal Science, aut HENRY P. R. Departments of Animal Science, aut AMMERMAN C. B. Departments of Animal Science, aut LITTELL R. C. Statistics, and aut MILES R. D. Dairy and Poultry Science, University of Florida, Gainesville, Florida 32611-0900 aut Poultry Science Oxford University Press 75/4(1996-04), 495-504 0032-5791 75:4<495 1996 75 ps https://doi.org/10.3382/ps.0750495 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.3382/ps.0750495 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- CAO J. Departments of Animal Science aut NATIONALLICENCE 700 1- LUO X. G. Departments of Animal Science aut NATIONALLICENCE 700 1- HENRY P. R. Departments of Animal Science aut NATIONALLICENCE 700 1- AMMERMAN C. B. Departments of Animal Science aut NATIONALLICENCE 700 1- LITTELL R. C. Statistics, and aut NATIONALLICENCE 700 1- MILES R. D. Dairy and Poultry Science, University of Florida, Gainesville, Florida 32611-0900 aut NATIONALLICENCE 773 0- Poultry Science Oxford University Press 75/4(1996-04), 495-504 0032-5791 75:4<495 1996 75 ps Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford