Mature Minipigs Seek and Prefer Novelty

The novel object recognition (NOR) test is a toolset to determine the affective state of an animal because it quantifies cognitive abilities as they relate to memory, appetitive behaviors, and neophobia. The objective of this pilot study was to establish a NOR-standard operating procedure for mature mini-pigs (n = 8; age 25.6 ± 3.7 SD wk; NSRRC, Columbia, MO) housed individually in a biomedical facility (K-state Large Animal Research Center, Manhattan, KS). During a two week acclimation period, each pig was moved to a clean, empty test arena for 190 ± 5.22 SD sec and received twice-daily exposure to a red-ball (Familiar object; FO; Red-ball, The Kong Company, Golden, CO) during feedings. After the acclimation period (day 0), videos of the 3-min tests were collected and analyzed (Observer 11.5, Noldus, Leesburg, VA) each day for 12 days. The pen was object-free on day 1. On days 2-6, two FO were placed in the pen in either the front or back positions. On days 6-12 pigs were tested twice with each of the novel objects (NO), which replaced both the front and back FO on successive days. Each NO object differentiated from FO by a factor (NO1 = Oblong Classic red-kong, The Kong Company; NO2 = textured green-ball, Leaps & Bounds, Petco; NO3 = textured orange stick, Smart snacker dog toy, Leaps & Bounds). Videos were continuously timestamped for exploratory (Oral-nasal-facial; ONF) and spatial behaviors (near NO, FO, other). Pigs spent 10 ± 1.87 % more time in an ONF-state when the test arena had a non-ball shaped NO (NO2 and NO3) than when it had only FO or the ball-shaped NO2 (P < 0.01). The increased-ONF were directed at NO or the rest of the pen (P < 0.05). Pigs spent the most time making contact with NO3 (P < 0.01) than other NO. Results indicate that pigs were able to recognize the differences in novel objects, and preferred the objects that were most different from the familiar object. This pilot study established methods that are repeatable and established baseline novelty-seeking measures in healthy, mature minipig. These methods may be used to detect pigs when they are in prepathological states of injury or sickness.