Redistribution of Extracellular Water and Sodium May Contribute to Saline Tolerance in Wild Ducks

Abstract

The compartmentalization of body fluids was measured in three species of ducks that differ in saline tolerance. Half of the birds of each species drank freshwater, while the other half drank saline (300 mM NaCl). Among ducks that drank freshwater, total body water (TBW) was similar among all species, but Barrow's goldeneyes (Bucephala islandica), the most marine species, had larger extracellular fluid volume (ECFV) than freshwater mallards (Anas platyrhynchos) or estuarine canvasbacks (Aythya valisineria). When acclimated to saline, only goldeneyes shifted extracellular water and Na+ into the intracellular compartment. ECFV was correlated with plasma aldosterone concentration in goldeneyes, but not in canvasbacks (aldosterone was not measured in mallards). Data summarized from the literature showed that TBW does not differ among terrestrial, freshwater, or marine species, but marine species have a larger part of their TBW in the extracellular compartment. Saline induced movement of extracellular water and Na+ into the cells only in goldeneyes. ECFV and redistribution of extracellular water and Na+ into the cells may be important components in saline tolerance of marine birds.

Production performance of Alabio ducks (Anas platyrhynchos Borneo) under different levels of drinking water salinity

“…No adverse effects were identified from the provision of drinking water with a salinity of 0.75–3.0 PSU on the egg shape index, yolk index (%), albumen index, and HU. This finding is consistent with Bennett et al [ 17 ], who pointed out that ducks could adapt to the salinity of drinking water that reaches 3 gm/l without affecting productivity. Likewise, Chen and Balnave [ 16 ] revealed that IsaBrown hens could maintain egg production and eggshell quality by including 2 gm/l NaCl in the drinking water.…”

“…Feed consumption of the controlled group did not differ from that of the treated groups because the duck’s capability to produce salinity from glandular secretions in their bodies was higher than that from drinking water [ 17 ]. This result indicated that Alabio ducks could tolerate NaCl provision up to 3 gm/l by increasing the availability of beneficial bacteria strains, such as probiotics, in the gastrointestinal tract [ 18 ].…”

“…Ducks are less sensitive to salinity than other waterfowl [ 17 ]. This evidence aligns with the current study, which found that Alabio ducks could acclimatize to the saline drinking water up to 3 gm/l without affecting the production performance.…”