CLOACAL ABSORPTION OF URINE IN BIRDS

A survey of interaction of renal and cloacal function in birds is presented. The domestic fowl [Gallus domestica] and the Australian xerophilic parrot, the Galah [Cacatua roseicapilla] were studied in particular. The retograde flow of ureteral urine into the coprodeum and large intestine markedly affects the osmolality and ionic composition of the contents of this segment of the gut. Potassium-ammonium-phosphate constitutes more than 50% of the osmolality of ureteral urine in dehydrated xerophilic birds. The cloacal sojourn of ureteral urine in dehydrated or salt depleted birds may result in conservation of 10-15% of ureterally excreted water and 2/3 of the NaCl. The adaptation of the cloacal transport parameters to salt loading/depletion and dehydration should be studied, particuarly in birds possessing a salt gland.