Bar, A., Department of Animal Science, The Volcani Institute of Agricultural Research, Bet Dagan, Israel
Hurwitz, S., Department of Animal Science, The Volcani Institute of Agricultural Research, Bet Dagan, Israel

1. 1. Changes in duodenal calcium-binding protein (CaBP) in the fowl (Gallus domesticus) were followed by the Chelex assay and gel electrophoresis. 2. 2. CaBP increased at the onset of egg production; the high level was sustained as long as egg production continued. A decrease in CaBP due to arrest of egg production occurred within 3-5 days. 3. 3. A long-term (16-32 days) calcium restriction resulted in an elevation of the CaBP level. 4. 4. There was no change in CaBP during shell formation. 5. 5. It was concluded that only some of the regulatory changes in calcium absorption in the laying fowl could be explained on the basis of changes in the CaBP level. © 1972.