| Summary: | 碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作研究所 === 91 === The objective of the thesis was to study the drinking behavior of dairy cows (Bos taurus). There were 142 Holstein dairy cows observed and compared in this study. The experiment was designed in the basis of two different housing systems (wet pad with force ventilation cooling house and open house); two different seasons (winter and summer); four different stages (high milk yielding cows, low milk yielding cows, dry cows and heifers); and grouping (home and visitor animals). All cows had free access to water. Dairy cows spent 13.8 min/day in wet pad house and 11.7 min/day in open house. However there was no significant difference in the duration of water drinking between these two housing systems (P>0.05). The water consumption was significantly higher in wet pad housed animals (68 l/day) than open housed animals (31.5 l/day) (P<0.05). A significant interaction between housing and grouping (P<0.05) was found. Home and visitor animals spent more time drinking in open house, wet pad house, respectively. A highly significant interaction was found between housing and drinking time during the day (P<0.001). Animals in open house drank more during the morning (6:00 to 10:00h), whereas wet pad housed animals drank in the afternoon (14:00 to 15:00h) and evening (18:00 to 20:00h). The average time a cow spent in drinking in summer was no significant difference than a cow drank in winter. However the water intake was significantly higher in summer (61.9 l/day) than in winter (38.6 l/day)(P<0.05). Drinking activity had a highly significant interaction between season and physiological stage (P<0.01). High milk yield cows spent more time drinking in summer than in winter, whereas cows in all other stages followed the opposite drinking pattern. Grouping exchange did not influence the drinking behavior of dairy cows in both seasons (P>0.05), measuring that both home and visitor animals spent almost the same time in drinking water. A strong significant interaction between season and time during the day was found (P<0.01), suggesting that animal’s high drinking frequency occurred during the day time for both seasons, with a the peak in the midday in winter and two peaks at 10:00h in the morning and 19:00h in summer. Thus, drinking behavior was associated with the cooler time in a day in summer and with the warmer hours in a day in winter. High low and milk yielding cows and heifers spent 15.3 min/day, 14.3 min/day, and 12.8 min/day, respectively in water drinking activity but there was no significant difference among them (P>0.05). There was however a significant difference in water drinking activity found in dry cows, which spent less time in drinking at 8.2 min/day (P<0.05).
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