An Evaluation of Differences in Mean Body Surface Temperature with Infrared Thermography in Growing Pigs Fed Different Dietary Energy Intake and Concentration

Abstract

Loughmiller, J.A., Spire, M.F., Tokach, M.D., Dritz, S.S., Nelssen, J.L., Goodband, R.D. and Hogge, S.B. 2005. An evaluation of differences in mean body surface temperature with infrared thermography in growing pigs fed different dietary energy intake and concentration. J. Appl. Anim. Res., 28: 73–80. Eighty pigs were used to determine the relationships among feed intake or diet composition and mean body surface temperature (MBST). In Exp. 1, 80 castrates (initially 24 kg) were allotted to one of the four feed intake levels [1.4x, 2.50x, 3.8x and ad libitum or 4.7x ME maintenance (MEm)]. Infrared (IR) thermographic images were collected at 0700, 1100 and 1900 h on d 4, 5 and 6. Quadratic effects were observed for ADG and G/F (P<0.05) and linear effects for ADFI (P<0.01) as ME intake increased. Treatment × time interactions were observed for MBST (P<0.01). The interaction was because MBST increased linearly at 0700 and at 1900 h as daily ME intakes increased (P<0.05) but increased quadratically with a plateau at 2.5x MEm at 1100 h (P<0.05). At 0700 h, MBST increased linearly as daily ME intakes increased from 1.5x MEm to ad libitum (P<0.05). In Exp. 2, pigs (initially 40 kg) were fed a common diet, and IR images were collected daily at 0700 h. Average daily gain was dependent upon changes in ADFI, mean body surface heat loss (MBSL) and the natural log of MBST (r2=.38; P<0.01). In Exp. 3, pigs (initially 59 kg) were allotted to diets containing 11.5, 12.6, 13.6 and 14.6 MJ ME/kg. Increasing dietary ME increased ADG, G/F, ME intake, MBST and MBSL (linear, P<0.05). The data indicate that IR thermography can detect MBST changes in pigs caused by changes in dietary intake or energy level. These changes can be detected under more variable environmental conditions than those used with a calorimeter and may be adapted as a low cost noninvasive tool to categorize factors impacting swine thermoenergetics.