Submitted to: European Conference on Precision Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/4/2015
Publication Date: 8/1/2015
Citation: Brown-Brandl, T.M., Hayes, M.D., Rohrer, G.A., Eigenberg, R.A. 2015. Thermal comfort evaluation of three genetic lines of modern pigs using thermal images. In: Guarino, M., Berckmans, D., editors. Precision Livestock Farming '15, September 15-18, 2015, Milan, Italy. p. 700-710.
Interpretive Summary: Swine thermal comfort is important for enhanced well-being and peak performance. As the genetics of swine have increased growth rate and changed carcass composition – the temperature at which pigs feel the most comfortable may have changed. A study was conducted to determine the ideal temperature for nursery pigs. Measurements taken include behavior observations, and thermal images. Two points of interest were evaluated – average skin temperature of the pig's trunk, and a centerline down the ear (from the head to the tip of the ear). The best temperature for Duroc sired pigs was 26.1°C, for Yorkshire sired pigs was 27.9°C, and for Landrace sired pigs was 28.8°C. It was determined that while both points of interest were valuable the pattern of temperature down the center of the ear was very helpful on determining piglet comfort. Overall, based on the results of this study the standard set point of 27.5°C is appropriate for nursery pigs.
Technical Abstract: Previous ARS research found that heat production of growing-finishing swine is 6 – 41% higher than documented in the ASABE and ASHRAE standards. The smallest changes were noted at the lightest weight pigs. This change is most likely due to larger, faster growing genotypes used in modern swine production. As a result of this higher heat production, the ideal temperature the pigs are kept at has likely changed. Thermal comfort of the new genetics is critical to maximize production and well being of the modern swine. Measurements of posture, skin temperature and ear temperature profile changes with temperature were evaluated for three modern pig genetic lines. A total 180 nursery pigs (30/sire – 3 different breeds: Duroc, Landrace, and Yorkshire) – with 2 sires for each breed) were acutely exposed (~6-hours) to each of seven different temperatures (20°C, 22.5°C, 25°C, 27.5°C, 30°C, 32.5°C, 35°C) over a 13-day period. Both group (10 pens of 18 pigs each) and individual pig (12 pigs/sire line - 36 total) thermal images were captured at each of the thermal conditions. In addition, time-lapse images were taken on a 5-minute basis to document posture. First region of interest (ROI) was the average truck surface temperatures; evaluated using an oval of the trunk of the pig. Temperatures along the centerline of the ear were evaluated for each pig (12 pigs/sire line - 36 total) as the second ROI. Changes in the average trunk surface temperature were fit to two separate linear regression equations – above and below the standard temperatures. Two regression lines were solved simultaneously to estimate the thermal comfort zone. The threshold temperatures were determined to be 26.1°C for Duroc sired pigs, 27.9°C for Yorkshire sired pigs and 28.8°C for Landrace sired pigs. Changes in ear surface proved to be a useful tool in evaluating thermal comfort. Based on the results of this study the standard set point of 27.5°C is appropriate for nursery pigs. These results demonstrate the ear is an ideal target for determining thermal comfort. Using current infrared temperature technology, an application could be developed to focused on the temperature of pig ears to ensure the building thermal environment is appropriate.