| Eight experiments were conducted to determine the effects of acute disease challenges and to determine the usefulness of infrared thermography (IR) to detect differences in mean body surface temperature (MBST) in growing pigs. In Exp. 1, 35 pigs were used to determine S. typhimurium effects on N balance, growth performance, and metabolic indicators. Salmonella typhimurium decreased short-term growth performance, and N balance, and increased the acute phase proteins (P < 0.05). In Exp. 2, 47 barrows were used to determine A. pleuropneumoniae effects on N balance, growth performance, metabolic indicators, carcass characteristics, and organ weights. Actinobacillus pleuropneumoniae decreased short-term growth performance, N balance, IGF-I, and increased two of three acute phase proteins (P < 0.05). In Exp. 3, four barrows were used to determine the MBST and ambient temperature relationship with IR. A linear relationship was observed (r2 = .97; P < 001). In Exp. 4, 24 pigs were used to evaluate febrile detection with IR following A. pleuropneumoniae infection. A febrile condition was detected following infection (P < 0.05). In Exp. 5, 80 pigs were used to evaluate differences in MBST associated with four feed intakes (0.75 x ME maintenance (MEm), 1.5 x MEm, 2.5 x MEm, and ad libitum) with IR. Differences in MBST by treatment were apparent (P < 0.05). In Exp. 6, 80 pigs were fed a common diet, and used IR to determine the relationship between growth performance and MBST. Daily gain is dependent upon changes in feed intake, mean body surface heat loss, and natural log of MBST (r2 = .38; P < 0.01). In Exp. 7,80 barrows were allotted to treatment (2,750 ME/kg, 3,000 ME/kg, 3250 ME/kg, or 3,500 ME/kg) to measure MBST differences with IR. Infrared thermography detected differences based upon treatment (P < .05). In Exp. 8, 80 pigs were assigned to treatment (12, 15.5, 19, or 22.5% total dietary CP) to measure MBST differences with IR. No differences were observed (P > 0.10). These results indicate that acute disease challenges have mainly short-term effects. Additionally, IR can detect differences in MBST due to fever or energy intake. |
