Studies on social facilitation in the feeding behaviour of the pig

Abstract

The relationship between social facilitation and feeding behaviour was studied, using growing and finishing pigs. The results showed that the pigs' feeding activity was influenced by their social environment.Both positive and negative social facilitation was found in the feeding behaviour of pigs kept in groups. The factors which caused these different types of social facilitation were studied. Moderate competition in an 8-hour feeding regime may produce positive social facilitation of feeding behaviour while serious competition, eg in a newly founded group, can cause negative social facilitation of feeding behaviour.Pigs with different social ranks show different reactions to the stimulation from their social environment, which produces different results with regard to social facilitation. The dominant pigs reacted more strongly to the social environment than the inferior pig in the present results.The group size of the pigs may also cause differences in social facilitation, but results are not clear on this point. The feeding speed of a companion pig seems to be unimportant in causing differences in social facilitation of the feeding behaviour of the subject pigs.The physical character of feeds may play an important rôle in influencing social facilitation in some circumstances. The present results demonstrated that, if the feeding drive is the dominant drive, it can be positively facilitated by social environment, but when the feeding drive is a subordinate drive, then social facilitation can be decreased by the social environment.The pigs showed strong allelomimetic behaviour in feeding activity. The food intake and eating speed of the pigs increased with increase in body weight but the total feeding time decreased, or kept constant, when the body weight increased. The eating speed may vary according to the following factors: the individual pig, the pig's body weight, competition, the length of the period of food availability and physical characteristics of the feeds. The pattern of feeding behaviour changes with increasing body weight. The present thesis also strongly indicates that the food in the form of meal is not as easily ingested by pigs as pelleted food.