Using the domestic chicken (Gallus gallus) as an in vivo model for iron bioavailability

Authors: TAKO, ELAD - Cornell University; RUTZKE, MIKE - Cornell University; Glahn, Raymond

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2009
Publication Date: 3/14/2010
Citation: Tako, E., Rutzke, M.A., Glahn, R.P. 2010. Using the domestic chicken (Gallus gallus) as an in vivo model for iron bioavailability. Poultry Science. 89:514:521.

Interpretive Summary: Our lab evaluated the use of a chicken model for iron absorption in animals. Two treatment groups (iron-deficient vs. iron-adequate)were tested since other animal studies have shown increased iron absorption when they were in iron deficient status. After 6 weeks, birds were anesthetized to expose a small intestinal loop to allow blood sampling and iron absorption of the animal. Iron absorption was higher in the iron-deficient birds and expression of proteins involved in iron uptake and transfer were also elevated in the low-iron group. These results indicate that this model may be useful as an intermediate test of in vivo iron bioavailability observations in preparation for subsequent human studies.

Technical Abstract: Iron fortification of foods and biofortification of staple food crops are strategies that can help to alleviate Fe deficiency. The broiler chicken may be a useful model for initial in vivo screening of Fe bioavailability in foods due to its growth rate, anatomy, size and low cost. In this study, we assess the broiler as a model for hemoglobin maintenance studies and present a unique duodenal loop technique for direct measurement of intestinal Fe absorption. One week old chicks were allocated into Fe deficient vs. Fe adequate treatment groups. For 6 weeks, blood hemoglobin (Hb), feed consumption and body weights (BW) were measured. At week 7, birds were anesthetized and their duodenal loops were exposed. The loop was isolated and a non-occlusive catheter was inserted into the duodenal vein for blood sampling. A stable isotope solution containing 58Fe (1mg Fe in 10 mM ascorbic acid) was injected into the loop. Blood samples were collected every 5 min and for 120 min post injection and analyzed by ICP-MS for 58Fe concentrations. In the low-Fe group, hemoglobin (Hb) concentrations, total body Hb-Fe and body weights were lower and hemoglobin maintenance efficiency (indicator for dietary iron availability) was higher than in the high-Fe group (P<0.05). Iron absorption was higher in the Fe-deficient birds (P<0.05). In addition, expression of proteins involved in Fe uptake and transfer, ie. Divalent metal transporter 1 (DMT1; Fe uptake transporter), Ferroportin (involved in Fe transport across the enterocyte) and Duodenal cytochrome B reductase (DcytB; reduces Fe at brush border membrane), were elevated in the low-Fe group. These results indicate that this model exhibits the appropriate responses to Fe deficiency and has potential to serve as a model for Fe bioavailability. Such a model should be most useful as an intermediate test of in vivo iron bioavailability observations in preparation for subsequent human studies.