ANALYSIS OF INDIVIDUAL-DIFFERENCES IN A HABITUATION PROCESS IN PIGS OF DUROC BREED

Habituation of orientation-investigative behavior was followed in 21 pigs of Duroc breed in a test chamber (320 x 420 cm) (boars n = 10, sows n = 11). In two 30-minute tests at the age of 90 days and 180 days at the mean weight of 34 kg and 96 kg the occurrence of locomotor activity (the number of grid crossings over the grid drawn on the floor of the test chamber - their frequency), voice signals (their frequency) and sniffs (their duration in time) was observed. The pigs show responses to stress in agreement with their behavioral characteristics. The data indicate negative impacts of stress on the behavior of pigs in social groups (canibalism, caudophagia, aggressivity), on their performance and carcass value. Therefore trials are focused on determination of optimum characteristics in the behavior of animals and of appropriate carcass values in relation to these characteristics. The acquired material makes it possible to evaluate CNS excitability and habituation process described by locomotor activity, voice signals and sniffs. A decrease in the frequency of locomotor activity was observed in all animals. As for age differences, three-month barrows and gilts were more active than six-month ones (Figs. 1 and 2). Voice signals were characterized by dishabituation in form of the higher frequency of voice signals in sows at the age of six months at the end of the test (Figs. 3 and 4). Evaluation of sniffs revealed insignificant differences between the sexes at the age of three months (p = 17.65%). On the contrary, the differences at the age of six months were significant (p = 99.97%, p < 0.01). While the frequency of sniffs was increasing in boars at the end of the test, sows showed habituation in 20 minutes (Fig. 6). The results make it possible to discuss the fact that the categories of behavior are different in the boars and in the sows at adolescence, as they are influenced by neurohumoral and physiological mechanisms, as well as there differences in behavior between the sexes in relation to innate investigative activity in the environment concerned. Besides the locomotor activity, the sows have an important ability of acoustic communication used in epimeletic signals of taking care of the young and to communicate with the young. In the investigative process of boars sniffs are dominant, besides the locomotor activity, in their territorial, social and sexual behavior.