Effects of social dominance, water trough location and shade availability on drinking behaviour of cows on pasture

The effects of water trough location and presence of shade on the behaviour of cows on pasture were investigated. The impact of social hierarchy on cows' use of shade and the water trough was also investigated. Thirty two non-pregnant dry cows were randomly divided in four groups in a 4 × 4 Latin square design. Each period had 14 days for habituation followed by 7 data days for collection. The treatments were: T1, shade was provided, and the water trough was located in the corridor; T2: no shade, and the water trough was located in the corridor; T3: shade was provided, and the water trough was located in the paddock; T4: no shade, and the water trough was located in the paddock. The animals were managed under rotational grazing, with an average of 4 days in a 0.1 ha paddock. Water troughs consisted of 500 L round PVC containers, 0.6 m high, positioned either at the corner of the paddock (T3 and T4) or in a 4 m wide access corridor, 150 m away from the paddock (T1 and T2). Shade consisted of a 24 m2 cover, 2.5 m high, located inside the paddock. Animals were observed for 12 h (6 am-6 pm), twice in each period. Instantaneous scans of each group were made every 10 min, and all drinking events, defecations and urinations were recorded. Water consumption was measured using a hydrometer attached to the water trough. In each group, all the agonistic interactions were recorded and the social status of each individual animal was estimated by the sociometric matrix model. Shade did not affect drinking behaviour. However, cows drank more often (P = 0.001), for longer periods (P = 0.02) and a larger amount (P = 0.02) when the water trough was inside the paddock than when it was in the corridor. Social hierarchy did not influence drinking behaviour when the water trough was placed inside the paddock (P = 0.3); however, when the water trough was located in the corridor, the number of drinking events (P = 0.05) and the time spent drinking (P = 0.05) were greater for dominant cows in comparison to subordinate cows. Social hierarchy did not influence the number of visits or the time spent in the shade, irrespective of the location of the water trough (P = 0.6). The location of the water trough and social hierarchy can influence drinking behaviour and water consumption by cows managed in rotational grazing systems.