Drinking behavior in nursery pigs: Determining the accuracy between an automatic water meter versus human observers

Authors: MEISZBERG, ALLISON - IOWA STATE UNIVERSITY; JOHNSON, ANNA - IOWA STATE UNIVERSITY; SADLER, LARRY - IOWA STATE UNIVERSITY; Carroll, Jeffery - Jeff Carroll; Dailey, Jeffery; KREBS, NADEGE - TEXAS TECH UNIVERISTY

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2009
Publication Date: 8/14/2009
Citation: Meiszberg, A.M., Johnson, A.K., Sadler, L.J., Carroll, J.A., Dailey, J.W., Krebs, N. 2009. Drinking behavior in nursery pigs: Determining the accuracy between an automatic water meter versus human observers. Journal of Animal Science. 87:4173-4180.

Interpretive Summary: Behavioral observation is a type of tool used to quantify animal biological responses. Behaviors and postures can be classified as either behavioral events, whereby the behavior performed by an animal is relatively short in duration (for example drinking), or behavioral states, which by definition last a longer period of time (such as lying). To facilitate the collection of behavioral events and states, ethologists are able to choose between different sampling rules; ad libitum, focal and scan sampling, and continuous. Each sampling rule has both challenges and benefits. For example, scan sampling becomes appropriate when the observer wishes to record behavioral states, but data could be lost if a scan sample is used to record behavioral events like drinking due to its shorter duration. Continuous observation is, therefore, preferred to acquire drinking behavior, but this is time consuming and labor intensive. Furthermore, behavioral methodology should be used like physiological methodologies, in that they should be selected and validated based on the objectives of a given study. Therefore, if an automatic device could accurately record time spent at a waterer and the number of visits to a waterer, it would be a valuable alternative to the traditional use of human observers for behavioral studies and could reduce the labor and expenses associated with the collection of behavioral data. Scientists within the Livestock Issues Research Unit and Iowa State University conducted a collaborative research study to determine the accuracy in the time spent at the waterer and the number of visits to the waterer by individually housed nursery pigs between human observers scoring video files using Observer software (OBS) and an automatic water meter Hobo (WMHOBO, control) affixed onto the waterline. In addition, the amount of water consumed and wasted by individual pigs provided with ad libitum access to a nipple waterer was recorded. Collectively, the data from this study indicated that the use of the traditional OBS method for quantifying drinking behavior in pigs can be misleading and that quantifying drinking behavior, and perhaps other behavioral events, via the OBS method must be more accurately validated in future research studies. Perhaps a definition of 'drinking behavior' using actual water ingestion and the notion of bout would lead to a better accuracy with OBS, though we suggest that drinking behavior should not be recorded by human observers but by automatic recording devices. Practically, an automated system such as that used in the current study could also be used to generate alerts when the drinking pattern changes, allowing for a better management of the pig herd health, productivity, and overall well-being. The results from this study will be of interest to scientists working in the fields of animal behavior, swine production, and swine health. The information may also be useful to swine producers in the implementation of management systems that could be used to monitor water intake in their herds.

Technical Abstract: Assimilating accurate behavioral events over a long period can be labor intensive and relatively expensive. If an automatic device could accurately record the duration and frequency for a given behavioral event, it would be a valuable alternative to the traditional use of human observers for behavioral studies. Therefore, the objective of this study was to determine the accuracy in the time spent at the waterer and the number of visits to the waterer by individually housed nursery pigs between human observers scoring video files using Observer software (OBS) and an automatic water meter Hobo (WMHOBO, control) affixed onto the waterline. Eleven PIC USA genotype gilts (22 ± 2 d of age; 6.5 ± 1.4 kg BW) were housed individually in pens with ad libitum access to a corn-based starter ration and one nipple waterer. Behavior was collected on d 0 (day of weaning), 7, and 14 of the trial using one color camera positioned over four attached pens and a RECO-204 DVR at 1 fps. For the OBS method, two experienced observers recorded drinking behavior from the video files, which was defined as when the gilt placed her mouth over the nipple waterer. Data were analyzed using non-parametric methods and the general linear model (GLM) and regression procedures in SAS. The experimental unit was the individual pen housing one gilt. The GLM model included the method of observation (WMHOBO vs. OBS) and time (24-h) as variables and the gilt nested within method was used as the error term. Gilts consumed more water (P = 0.04) on d 14 than on d 0. The time of day affected (P < 0.0001) the number of visits and the time spent at the waterer regardless of the method. However, the OBS method underestimated (P < 0.0001) the number of visits to the waterer (3.48 ± 0.33 visits/h for OBS vs. 4.94 ± 0.33 for WMHOBO) and overestimated (P < 0.0001) the time spent at the waterer (22.6 ± 1.46 s/h for OBS vs. 13.9 ± 1.43 for WMHOBO) compared to WMHOBO. The relationship between the two methods for prediction of time spent at the waterer and number of visits made by the gilts was weak (R2 = 0.56 and 0.69, respectively). Collectively, these data indicate that the use of the traditional OBS method for quantifying drinking behavior in pigs can be misleading. Quantifying drinking behavior, and perhaps other behavioral events, via the OBS method must be more accurately validated.