The transport of serum iron in hens in relation to laying

Abstract

Several authors (1, 2) have studied different aspects of iron’s metabolism on laying hens. They observe how upon rising its consumption due to the production of the egg, the sideremia rises considerably due to a rise in its absorption and to a mobilization of the reserves. They have not paid attention to the transports mechanisms of this high serie iron and thisproblem is the object of this paper.

We have studied 23 roosters, 23 hens not in laying and 16 laying hens. In all of them the serum iron and the total binding capacity has been determined following Ransay’s me- thod (4, 5). From both valúes a third has been calcu1ated. the so called saturation coefficient. The results can be observed on Tables I, II, and III, and on Table IV the average valúes, errors and deviations from the standard have been grouped. The sideremia valúes (S), and the total binding capacity

(CTF) is sensibly lower in the rooster (with a statistical signifi- cance) than in the hen, even if they are in laying or not. Limi- ting ourselves to the hens, the sideremia valúes are enor- mously higher in those that are in laying. Even so the CTF valúes in both groups of hens are sensibly equal and the small difference there appears is not statistically significative. The saturation coefficient valúes (CS) transíate what already has been said and so while the valúes corresponding to roosters and hens not in laying are lower than 100 (normal), in the layiny hens they are higher than said value.

Therefore there is an outstanding fact, and at first wiew it is illogical, this is that the sideremia in the laying hens issuperior to the serum’s iron transport capacity. This pheno- mcnon admits only one explanation and we have to look for it in the method used to determine the total binding capacity. This method consists, the one used by us (5), in adding iron in excess to the serum in order to satúrate the siderophiline, eliminating the surplus with MgCO3. Therefore, in our case,part of the circulating iron must be bound in such a way that the affinity that the carbonate has for it, turns out to be higher to that of the protein which transports it. This we have been able to verify by the simple addition of MgCO3 (compare the S and the Sme, sideremia after the addition of MgCO3, valúes) on Tables I, II and III.

It remains to be decided if this iron, unstably bound, is so to the siderophiline (even though in a form other than normal) or to another proteic fraction.

This problem is discused with the existing bibliographic facts, taking into consideraron the possible intervention of conalbumin (3). In any way, we hope that the works going on at the present with Fe-59 will allow to clear up this problem.