Factors Affecting Water Consumption by Holstein Cows in Early Lactation

Our objective was to examine relationships between water intake by dairy cows in early lactation and dry matter intake, milk production, sodium intake, and ambient temperature. After parturition, 19 multiparous Holstein cows were assigned randomly to one of four diets for 16 wk. Water consumption, dry matter intake, milk production, and maximum and minimum temperature were recorded daily and averaged weekly. There was no significant dietary effect on water intake, dry matter intake, or milk production; therefore, data were analyzed by stepwise multiple linear regression across diets. The final equation was: water intake (kg/day) = 15.99 + 1.58 (standard error .271) × dry matter intake (kg/day) + .90 (.157) × milk production (kg/day) + .05 (.023) × sodium intake (g/day) + 1.20 (.106) × minimum temperature (°C). Coefficient of multiple determination was .59. All temperature measures (mean, minimum, maximum) were closely correlated which justified the use of only one. Dry matter intake and milk production also were correlated but out of phase. Regression coefficients for milk production and sodium intake agreed with literature estimates. Major factors determining water consumption in early lactation have been identified and quantitated.