Physiological Relationship Between Thirst Level and Feed Intake in Goats Fed on Alfalfa Hay Cubes

다국어 초록 (Multilingual Abstract)

The present study was carried out to measure changes of feed intake and thirst level caused by water deprivation in goats fed on dry feed and to elucidate the relationship between those two parameters. Water deprivation significantly (p<0.01) decreased cumulative feed intake and rate of eating at 30, 60, 90 and 120 min, respectively, after feed presentation. Cumulative feed intake, after completion of 2 h feeding, was reduced by about 20, 21 and 64 % due to water deprivation during feeding for 2 h (WD2), for 22 h (WD22) and for 46 h (WD46), respectively, compared to free access to water (FAW). Compared to the FAW, WD2, WD22 and WD46 increased thirst level by about 5, 5 and 9 times, respectively. Mean thirst level (X, g/30 min) was negatively correlated with cumulative feed intake (Y, g DM) after completion of 2h feeding (Y=1302-0.2 X, $r^2=0.97$, p<0.05). Water deprivation depressed plasma volume and there was a significant positive regression between plasma volume (X, ml) and cumulative feed intake (Y, g DM) after completion of 2h feeding (Y=-1003+0.6 X, $r^2=0.99$, p<0.01). Mean plasma osmolality (X, mOsmol/l) correlated significantly and negatively with cumulative feed intake (Y, g DM) after completion of 2h feeding (Y=27004-84.9 X, $r^2=0.95$, p<0.05). In conclusion, a decrease of feed intake during water deprivation is mainly due to an increase of thirst level quantitatively, and the act of feeding itself induces thirst more than the length of water-deprivation periods in goats fed on dry feeds. The present findings suggest that plasma osmolality and plasma volume which affect thirst level are involved in the decrease of feed intake in water-deprived goats.