ANALYSIS OF INDIVIDUAL-DIFFERENCES IN A H ABITUATION PROCESS IN PIGS OF DUROC BREED

Habituation of orientation-investigative behavior was followed in 21 p igs of Duroc breed in a test chamber (320 x 420 cm) (boars n = 10, sow s n = 11). In two 30-minute tests at the age of 90 days and 180 days a t the mean weight of 34 kg and 96 kg the occurrence of locomotor activ ity (the number of grid crossings over the grid drawn on the floor of the test chamber - their frequency), voice signals (their frequency) a nd sniffs (their duration in time) was observed. The pigs show respons es to stress in agreement with their behavioral characteristics. The d ata indicate negative impacts of stress on the behavior of pigs in soc ial groups (canibalism, caudophagia, aggressivity), on their performan ce 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 mat erial makes it possible to evaluate CNS excitability and habituation p rocess described by locomotor activity, voice signals and sniffs. A de crease in the frequency of locomotor activity was observed in all anim als. As for age differences, three-month barrows and gilts were more a ctive than six-month ones (Figs. 1 and 2). Voice signals were characte rized by dishabituation in form of the higher frequency of voice signa ls in sows at the age of six months at the end of the test (Figs. 3 an d 4). Evaluation of sniffs revealed insignificant differences between the sexes at the age of three months (p = 17.65%). On the contrary, th e 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 be havior are different in the boars and in the sows at adolescence, as t hey are influenced by neurohumoral and physiological mechanisms, as we ll as there differences in behavior between the sexes in relation to i nnate investigative activity in the environment concerned. Besides the locomotor activity, the sows have an important ability of acoustic co mmunication 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 territor ial, social and sexual behavior.