Evaluation of drinking water intake, feed water intake and total water intake in dry and lactating cows fed silages

Data of 46 water balance measurements were collected from dry and lactating Holstein cows in the controlled climatic chamber, which maintained at 20 degrees C and 60% relative humidity, to evaluate between drinking water intake (DWI), feed water intake (FWI), total water intake (TWI) and some variables in cows. Orchardgrass silage, alfalfa silage and corn silage were offered in dry cows, and alfalfa or orchardgrass silage and concentrates were given as a TMR in ratio of 60:40 in lactating cows. DMI and milk production were highly related to DWI and TWI of lactating cows. DWI in dry and lactating cows increased and FWI decreased as dietary DM increased, but there was a very weak correlation between dietary DM and TWI. In both dry and lactating cows, positive correlations were obtained between dietary CP or K and TWI, especially highly correlations between dietary K and TWI. There were strong positive correlations between N intake, K intake or urine volume and TWI rather than DWI in dry and lactating cows. These results suggest that dry and lactating cows accelerate DWI to excrete large amounts of K or N into urine in excess of their needs, but TWI is more suitable to evaluate the effects of dietary CP or K on water intake and urine volume in dairy cows. (C) 2009 Elsevier B.V. All rights reserved.