Published online by Cambridge University Press: 18 August 2016
Quantitative water intake and excretion, urinary osmolality and urinary excretion of Na, K and cortisol were studied in an experiment with nine adult male mink. The experiment comprised four periods each of 3 days, and ambient temperature (Ta) was increased from 5°C to 20 °C (periods 1 to 2) and, after an interval of 1 day, continued at 20°C and then decreased to 5°C (periods 3 to 4). Three different water supplies were given, namely E: extra water in the food, N: normal ad libitum water supply or R: restricted, free access to drinking water twice daily. Intake of metabolizable energy (ME) was calculated, and the water intake and excretion data were related to ME intake. The effect of Ta on quantitative water intake and excretion was evident, with the greatest response recorded when Ta was decreased. Intake of drinking water was highest at 20 °C, as well as the total water balance. The water supply had some, but not a profound, influence on water intake and excretion, with tendencies for reduced drinking water intake and water excretion in urine for R mink. Intake of ME decreased during period 3 at 20 °C and then increased when Ta was decreased to 5°C, which was reflected by an increased 24-h excretion of Na and K as well as an increased osmolality of the urine. Therefore, it was concluded that water intake and excretion were affected by combined effects of Ta and ME intake. Generally, it was shown that the mink responded rapidly to changes in Ta, and within 24 h significant effects of the change could be recorded for several of the traits studied.
Present address: Department of Animal Science and Animal Health, Royal Veterinary and Agricultural University, Bülowsvej 13, DK-l870 Frederiksberg C, Denmark.