Effects of Water-Deprivation on Renal-Function and Plasma Arginine Vasotocin in the Feral Chicken, Gallus-Gallus (Phasianidae)

Abstract

Feral chickens occur on a coral atoll off the coast of Queensland, Australia, where the availability of water is limited. Glomerular filtration rate (GFR) was measured in conscious unrestrained feral chickens by means of osmotic minipumps in fully hydrated birds and in birds subjected to a four-day period of water deprivation. Plasma ionic and osmotic concentrations were measured on each day of the experiment. During water deprivation, body weight decreased and plasma ionic and osmotic concentrations increased. Haematocrit was not significantly affected by dehydration. GFR fell on days 2, 3 and 4 of water deprivation to 62% of hydrated values. The plasma levels of the avian diuretic hormone, arginine vasotocin (AVT), increased by a factor of 2.8 over the period of water deprivation. The sensitivity of release of AVT in the feral chicken is higher than that reported for domestic strains of chickens. This may be related to the ability of the feral strain to survive in regions of limited water availability. GFR was measured also by the 'constant infusion' method, which was not significantly different from GFR measured by osmotic minipumps.