Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/1998
Publication Date: N/A
Technical Abstract: Pigs have been selected to gain weight rapidly and deposit minimal amounts of fat. Combining genotype selection with segregated early weaning raises questions about the behavior and well-being of the pig. Two groups of 44 d old pigs were compared using a completely randomized design. One treatment group was selected for high levels of lean gain (Hi-L) (n=12) and the other rwas selected for low levels of lean gain (Lo-L)(n=12). The effect of genotype on behavior was compared using an open-field arena (150 cm X 180 cm). Pigs were tested for 5 min and vocalization, defecation and activity level was recorded. Salivary cortisol samples were collected immediately after the open-field test and at 15, 30 and 45 min post-behavioral test. Results indicated higher levels of activity in the Lo-L treatment group compared to the Hi-L (P<.05). There was large variation in the number of of vocalizations regardless of treatment. Due to this variability, no treatment differences were detected. Higher levels of activity usually suggest less anxiety and more interest in exploration of the environment. Defecation indicates an increase in anxiety in a novel situation. However, there was a trend toward a positive correlation between defecation and activity level (P=.09). Although baseline cortisol levels were higher in the Lo-L compared to the Hi-L group (P<.05), a repeated measure analysis of cortisol did not suggest significant treatment differences in salivary cortisol over time. Pigs selected for a lower lean-gain showed higher activity level in the open-field test. It is possible that by selecting for high lean gain, an animal's ability to cope with a novel situation is changed, thus affecting the well-being of the animal.