Drinking behavior of lactating dairy cows and prediction of their water intake.

The water intake of 41 lactating dairy cows managed according to current dairy farm practices was individually and continuously monitored to 1) investigate drinking behavior and 2) determine factors affecting water intake. The cows were housed in a free-stall barn and fed once daily with a corn silage and concentrate-based total mixed ration (48% dry matter content; 20.6 +/- 3.3 kg/d of dry matter intake). Cows were milked twice daily, with a yield of 26.5 +/- 5.9 kg/d. The daily free water intake (FWI) was 83.6 +/- 17.1 L, achieved during 7.3 +/- 2.8 drinking bouts. The drinking bout water intake was 12.9 +/- 5.0 L. Almost three-fourths of the FWI occurred during working hours (0600 to 1900 h). Consumption peaks corresponded to feeding and milking times. More than one quarter of the daily FWI was met during the 2 h after each milking. About 75% of the present cows visited the watering point at least once during the 2 h after the evening milking. It is probable that drinking behavior evolved with lactation, but further studies are required to identify the relationship between lactation stage and drinking behavior. The most relevant factors affecting the daily FWI of lactating cows were best combined according to the following predictive equation: (R(2) = 0.45; n = 41 cows, n = 1,837): FWI, L/d = 1.53 x dry matter intake (kg/d) + 1.33 x milk yield (kg/d) + 0.89 x dry matter content (%) + 0.57 x minimum temperature ( degrees C) - 0.30 x rainfall (mm/d) - 25.65. The results obtained using these equations were in agreement with the equations developed by other researchers.