Effect of sensory stimuli on huddling behavior of pigs

Two experiments involving pigs at 1, 3, and 8 d of age were conducted to 1) compare huddling between littermates and nonlittermates, 2) study the abil ity of pigs to distinguish an anesthetized piglet from a piglet-shaped obje ct, and 3) explore the importance of physical contact between pigs on huddl ing behavior. Experiments were conducted in an enclosed rectangular aluminu m test chamber having pressure sensors beneath floor panels to detect test pig location. Test objects were placed on a platform at one end of the cham ber and test pig location was monitored during a 45 min trial. Experiment 1 involved a total of 45 pigs (5 pigs/treatment on d 1, 2, and 3). The resul ts indicate that, regardless of age (P > .05), when either a littermate or a nonlittermate occupied the platform, average location of test pigs that " settled" (ceasing to move for 7 min or more) was closer to the platform (P < .01), time spent near the platform was greater (P < .01), and movement ab out the chamber was less (P < .01) than when the platform was empty. No dif ferences (P > .05) were observed between littermate and nonlittermate stimu li for these variables. During Exp. 2, the platform was covered with wire m esh. A total of 98 pigs were used in the study. Treatments were a cage cont aining 1) no object (n = 24), 2) a wooden block (n = 25), 3) a pig-shaped l atex casting (n = 24), or 4) an anesthetized 8-to 10-d-old pig (n = 25). Pi g age and treatment did not affect the percentage of time in each trial tha t pigs spent within 23.5 cm of the cage or the percentage of pigs settling within 23.5 cm of the cage. These studies show that pigs huddle similarly w ith littermates and nonlittermates and that physical contact with another p iglet but not visual recognition of another piglet affects piglet huddling.