The objective of this study was to investigate the effects of different trough types on the water consumption and drinking behaviour of pasture-based beef heifers. Two trials were implemented with 32 beef heifers to test two different types of water troughs, namely a rectangular concrete trough (RC) and a round polyvinyl chloride water tank (PVC). In Trial 1, both troughs were simultaneously available to groups of four animals within eight paddocks. In Trial 2, the animals were distributed in pairs throughout 16 paddocks and, in a crossover design, were exposed to one type of trough at a time. In both trials, estimated water intake was per four animals. Number of drinking bouts, time spent drinking and amount of water intake from the RC and PVC trough were recorded in both trials. Data were statistically analysed by analysis of variance. In Trial 1, group and trough effect were in the model. In Trial 2, stage, pair and trough were tested. In Trial 1, where both types of troughs were available, animals had a higher number of drinking bouts (3.32 v. 0.57 6 0.09; P , 0.01), longer drinking periods (144.21 v. 22.81 6 7.3 s; P , 0.01) and greater intake (160.21 v. 23.76 6 13.06 l; P , 0.01) from the PVC water tank, compared to the RC trough. In Trial 2, all groups drank more often (5.10 v. 3.28 6 0.32; P , 0.001), for longer periods (167.23 v. 115.23 6 15.61 s; P , 0.02) and with higher intake (141.36 v. 118.47 6 5.01 l; P , 0.02) from the PVC than from the RC trough. Thus, heifers not only prefer, but also drink more from a PVC water tank in comparison to a RC trough.
Water is a major nutrient for all animals, affecting dry matter intake, health and productivity. Our research shows that pasture-based beef cattle have preferences over what type of water trough to drink from and that the trough type offered may affect water consumption as well. When exposed to two types of water troughs, a rectangular concrete trough and around polyvinyl chloride (PVC) tank, cattle drank more often, for longer periods and with higher intake from the PVC trough. Maximizing water intake is a low-cost investment with
immediate results and prompt rewards that may still affect production and welfare positively.
Brazil has the largest cattle herd in the world (FAO, 2008),and most of its beef production relies on pasture. Water supply may be a major constraint on the welfare, health and productivity of cattle on pasture. It is known that if given the choice, cattle will drink more often from a water trough than from a stream or pond (Sheffield et al., 1997; Bica, 2005). Despite prevailing recognition of the nutrient value of water (NRC, 2000), few plans and investments are made in relation to animal water supply, especially when dealing with pasture-based systems. This is particularly evident in pasture-based beef cattle farming, where secular traditions of herd handling generally supplant techniques. Water access may perhaps be more important than
quantity. Factors which interfere with animal access to resources, such as water and feed, are space per animal, density and distribution of animals, quantity of available resources, time at hand when resources are accessible and internal social organization of the group (Albright, 1993; Ho¨tzel et al., 2003). Using tanks instead of direct natural sources of water, as preferred by cattle, enhances water intake and animal weight-gain, hence improving animal performance and welfare, and economic and environmental efficiency (Bica et al., 2006)
Cattle prefer tanks to natural bodies of water in as much as the trough design can affect water intake among cattle and other animal species. Nyman and Dahlborn (2001) observed a greater water intake from buckets when compared to automatic troughs among horses, possibly due to greater ease for drinking. Sows prefer suspended nipple drinkers with heights varying from 51 cm to 76 cm (Phillips et al., 2001). Newborn piglets, on the other hand, prefer bowl drinkers of wider formats (Phillips and Fraser, 1990). Greater consumption rates among animals with favoured supplies suggest that productive systems should take their
forms into consideration for possible increases of productivity, of animal welfare and of profits for producers.
Animals apparently seek a more comfortable, less energy-consuming way of obtaining water. Studies have
demonstrated that cows prefer certain types of troughs and that they drink more water when provided in preferred tanks. Dairy cows prefer larger troughs with larger surface areas (Machado Filho et al., 2004; Teixeira et al., 2006). When water is restricted, social dominance interacts with physiological states and dominant lactating cows drink more water; subordinate dry cows can stay up to 48 h without drinking any water (Ho¨tzel et al., 2003).
When studying water supply, beef cattle have received less attention than dairy cows. The impact of lack of water on dairy production is immediate. To produce a kilo of milk, a cow must consume 3 to 5 l of water (National Research Council, 2001), and, as such, the effect of water intake is more evident in dairy than in beef cattle. Although the relevance of the matter has already been demonstrated for dairy cows (Ho¨tzel et al., 2003; Machado Filho et al., 2004; Teixeira et al., 2006), until today we do not know of any study which has analysed the influence of trough type on the water intake of pasture-based beef cattle. Hence, the objective of this study was to uncover the influence a trough type might exert on the drinking behaviour and water intake of pasture-based beef heifers.
In Trial 1, when animals had access to both water trough types, the number of drinking bouts, time spent drinking and water intake was greater in the PVC than in RC water tank (Figure 2).
As in Trial 1, in Trial 2, heifers with access to only one trough type at a time drank more often for longer periods and had a higher water intake when the PVC water trough was available (Figure 3). During the first stage of Trial 2, air temperatures were lower and relative humidity was higher than the second stage (Table 1). Accordingly, in the second stage, heifers individually spent more time drinking (98 v. 184 6 15 s/day; P 5 0.001) and water intake by the groupwas greater (113.9 v. 145.9 6 5.5 l/day; P 5 0.006).
Various factors may have led the heifers to use the PVC trough more. This round and polyvinyl chloride tank was larger, whereas, the rectangular and concrete trough was smaller and lower. Trials with dairy cattle have been conducted in order to disclose the physical factors that effectively influence cow trough preference. Machado Filho et al. (2004) have revealed that cows prefer larger troughs, with greater water surface and depth. These authors verified a greater number of drinking bouts, time spent drinking and water intake at a larger trough (60 cm height; 139 3 95 cm) over a smaller one (30 cm height; 126 3 68 cm). In another
experiment, Teixeira et al. (2006) tested preference, comparing two different troughs in terms of surface area, height and depth. Their findings attested to a relation between the water surface and the animals’ preference: drinking bouts were more frequent, time spent drinking was longer and water intake was greater from the trough of larger water surface.
As in Trial 1 of this experiment, Teixeira (2005) also tested the drinking behaviour of dairy cows in troughs of different formats and sizes. In this particular study, three distinct but commonly utilized troughs in pasture-based systems were compared by means of preference trials: one was a round 500 l trough (60 cm height 3 120 cm diameter), another a round 125 l trough (60 cm height 3 60 cm diameter) and a third rectangular 100 l trough (30 cm height 3 100 cm length 3 60 cm width). The animals preferred the first trough, having there drank more often, spent more time drinking and ingested more water.
The latter-favoured trough had the same dimensions of the most utilized trough in this experiment. This thus indicates that pasture-based bovine, dairy cows and beef heifers prefer troughs of larger water surfaces, quite like the PVC trough of this study.
The estimated daily average intake per animal at the troughs was 29.6 l at the RC trough and of 35.6 l at the PVC tank. The total daily requirements of water intake (water contained in feed, produced by the body’s metabolism and of free intake) for beef heifers with an approximate weight of 273 kg ranges from 29.5 to 48.1 l, in average temperatures of 21.18C to 32.28C (National Research Council, 2000), as were the conditions of this experiment. The heifers were, hence, drinking adequate amounts of water according to the indications of the NRC. Water consumption is highly associated to the intake of dry matter (National Research Council, 2000). Even though we did not measure the dry matter content of the heifers’ diet, we may consider that the content of both treatments was equal, since the paddocks were set up on the same pasture. A greater free intake of water, as such, may stimulate a greater intake of feed and, consequently, a greater weight-gain. This is the explanation of Bica et al. (2006) for greater weight-gain of pasture-based beef cattle which had either a trough or a natural rain basin as water source.
The experiment was conducted under high temperatures, during the hottest months of the summer, when the average temperature was above 258C. Temperature and humidity have a direct relation with water consumption among cattle (Murphy et al., 1983; Murphy, 1992; Rouda et al., 1994). Additional water requirements of young calves are 0.5 l/day for each additional degree Celsius of air temperature (Meyer et al., 2006). In this study, this tendency was also observed: in Trial 2, time spent drinking and intake increased in the second stage, thus, in accordance to the hotter and dryer conditions of the weather at the time.
Other authors have also noted a correlation among cattle between water intake and rises in air temperature and falls in relative humidity (Meyer et al., 2004). Loneragan et al. (2001) have found the daily average temperature to be responsible for 25.7% of an observed variation in water consumption.
We conclude that the trough type not only affected the drinking behaviour of pasture-based beef heifers but water intake as well. Observations show a preference, leading to increased intake, for round PVC tank water over RC trough water.
