A study on the effect of pig ratio to cup waterers in a pen was performed by researchers at Iowa State University, in cooperation with Boehringer Ingelheim Vetmedica, Inc. (BIVI) and Cargill Pork.

The results of the study showed that pigs having access to three waterers in a nursery pen drank more frequently than those provided with one or two cup-waterers per pen. Additionally, there was a trend for pigs provided two or three cup-waterers per pen to have increased average daily gains, however these results were not statistically significant.

The recommended number of waterers for nursery pigs is one waterer for every 10 pigs. However, in general, pork producers in the United States tend to have one waterer for every 25 pigs. Because of this, the trial was set up using 25 nursery pigs per pen.

BIVI was interested from the standpoint of further understanding drinking behaviour as related to group vaccination via drinking water. "We investigated this with Anna Johnson's help a few years ago," says Roy Edler, Field Research Services Group Leader, for BIVI.

"You need to allow 4 to 6 hours for all pigs in a group to get an immunizing dose. We would hope that providing more water sources would increase the pig's opportunity to consume water and vaccine."

The importance of nursery system design, in regard to the impact of drinkers is limited, say the authors. "Previous work has addressed swine feeder placement and design. Therefore, the objectives of this study were firstly to determine the total number of visits made to a water bowl drinker by pigs over a 6-hour period and second, to calculate average daily gain when pigs were offered either one, two or three water-bowl drinkers per pen."

A total of 225 crossbred gilts weighing approximately 5.38kg (11.84lbs.) were housed in nine pens that provided for 0.22m²/pig (2.45 square feet per pig) in a commercial nursery facility near Jefferson City, Missouri. The research was conducted over six weeks from October to December 2006. The nursery was equipped with side curtains providing the pigs with a natural lighting cycle.

Further studies will likely be designed for wean-to-finish units, since many operations no longer have traditional nurseries. Mr Edler explained, "There is the behavioural aspect of [these units] that has not been touched on yet, and this will be important."

Pigs were housed on plastic slatted flooring, and pens were separated using steel pipe gating (0.91m or 3 feet in height). Pigs had ad libitum access to a pelleted corn/soybean-based diet formulated to meet nutritional needs.

A total of nine pens were used for behavioural and performance measures. Three pens per treatment were compared, all using stainless steel waterers. Treatment one (T1) is defined as one water bowl drinker per pen. This provided one water bowl drinker per 25 gilts per pen. Treatment two (T2) was two water bowl drinkers per pen. This provided one water bowl drinker per 12 gilts per pen. Treatment three (T3) is defined as three water bowl drinkers per pen, providing one water bowl drinker per 8 gilts per pen.

Gilts were approximately 7 weeks of age when behavioural observations were recorded over a two-day period (15 and 16 November 2006). One day prior to visual recording, all pigs were identified with an individual number placed between their shoulder blades, using an animal-safe crayon.

Individual pig weights were taken at placement (day 0) and at exit (day 42) for calculation of average daily gain (ADG).

Total number of drinking visits over 6 hours differed between the groups, with T1 and T2 pigs having fewer total visits (10.32±0.95 and 10.60±0.84) to the water bowl drinker when compared to T3 (13.88±0.84).

Ending weights for pigs on trial were 23.78±8.13 kg. There were no differences (P=0.06) for ADG (0.41±0.03, 0.43±0.02 and 0.46±0.02) between treatments, respectively.

The authors report, "This study demonstrated that when pigs were offered more places to drink, they visited the water bowl drinker more frequently over a 6-hour period, which tended to increase ADG in nursery-age pigs."

Additional studies will likely result from this work. For example, one might consider the cost benefit of adding more waterers to increase average daily gain.

"Providing additional water access may improve the gain, it will require more research to determine the full value of adding more water lines, etc." says Mr Edler of BIVI.

"What is not demonstrated in this study is the behavioural aspects of providing more waterers. If you put more waterers in the pen, will it change the pen dynamics? Will the smaller pigs drink more often?

"The hypothesis is that by providing more waterers you increase the pigs' opportunity to have more waterer visits," he continues.

"Again, referring to the behaviour, does adding more waterers reduce aggressive behaviour and what does that do to the social dynamics within the pen? These are questions that require additional research."

Physical placement of the waterers is also important, says Mr Edler, and this factor would also have behavioural implications. "I think continuing to investigate the previously mentioned aspects will be worth considering, in addition to looking at water consumption patterns over time."

The authors of the original report were: Larry J. Sadler, ag. specialist; Jill R. Garvey, undergraduate; Tony J. Uhlenkamp, undergraduate; Ciara J. Jackson, graduate student; Ken Stalder, associate professor; Anna K. Johnson, assistant professor of animal science; Locke A. Karriker, assistant professor, VDPAM; Roy A. Edler and J. Tyler Holck, Boehringer Ingelheim Vetmedica, IA, USA; Paul R. DuBois, Cargill Pork, KS, USA.