ABSTRACT
Behavior is one of the most commonly used indicators of illness; however, few studies have investigated how different common diseases affect animal behavior. This experiment was conducted to investigate behavioral and clinical alterations in growing pigs experimentally infected with Salmonella spp. during a 4-week post-infection period. A total of 48 growing pigs were divided into one of the three treatment groups (1) control, (2) infection with Salmonella Typhimurium or (3) infection with Salmonella Enteritidis. Individual pigs' behavior was recorded daily (0900 to 1100 and 1600 to 1800 h) using a video-recording system. Pigs in both infected groups had lower weight gain and feed intake during week 0 to 2 and 0 to 4 experimental period. Bacteriological data revealed that pigs in both infected groups persistently shed bacteria throughout the period of study. Oral infection of growing pigs with S. Typhimurium and S. Enteritidis significantly reduced the frequency of morning large (except week 1) and small movement throughout the study period. In the evening, significantly lowest frequency of movements were observed in the S. Enteritidis-infected group compared with the control. The standing and sitting frequency were significantly lower in both infected groups only at the morning of week 4. Infection with Salmonella spp. led to a significant reduction in the frequency and duration of morning eating and drinking throughout the experimental period, with the exception of 4th week drinking duration. The lowest frequency of evening eating during week 1 and 4 was recorded in both infected groups; whereas, the duration differed only at week 1. The evening drinking frequency only tended to decrease in response to S. Typhimurium infection at week 1. This study shows that, pigs infected with Salmonella spp. had poor performance, shedding high levels of Salmonella with their feces and reduced feeding and drinking activity, which are adaptive responses to infection and may help caretakers to detect ill health.