One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg)
Housing pigs within their thermal comfort zone positively impacts productivity and performance. However, fundamental information on behavioral thermoregulatory responses of individual and group-housed pigs is meager. As a gregarious species, pigs prefer to be near one another, touching and often hud...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-05-01
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| Series: | Animals |
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| Online Access: | https://www.mdpi.com/2076-2615/11/5/1447 |
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| author | Lindsey A. Robbins Angela R. Green-Miller Jay S. Johnson Brianna N. Gaskill |
| author_facet | Lindsey A. Robbins Angela R. Green-Miller Jay S. Johnson Brianna N. Gaskill |
| author_sort | Lindsey A. Robbins |
| collection | DOAJ |
| description | Housing pigs within their thermal comfort zone positively impacts productivity and performance. However, fundamental information on behavioral thermoregulatory responses of individual and group-housed pigs is meager. As a gregarious species, pigs prefer to be near one another, touching and often huddling. As pigs huddle together, they decrease their heat loss to the environment by decreasing exposed surface area and increasing mass. Additionally, pigs gain weight rapidly as they age. As an individual grows, their ability to withstand lower temperatures increases. We hypothesized that group size would alter pig thermal preference and that thermal preference would change based upon body weight. Thirty-six groups of pigs (n = 2 pigs/group) were tested in a factorial design based on group size (1, 2, or 4) and weight category (small: 5.20 ± 1.15 kg; medium: 8.79 ± 1.30 kg; and large: 13.95 ± 1.26 kg) in both sexes. Treatment groups were placed inside a chamber with a controlled thermal gradient (4.6 m × 0.9 m × 0.9 m; L × W × H) that ranged in temperature from 18 to 30 °C. Pigs habituated to the gradient for 24 h. The following 24 h testing period was continuously video recorded and each pig’s location during inactivity (~70% daily budget) within the thermal apparatus was recorded every 10 min via instantaneous scan sampling. Data were analyzed using a GLM and log10 + 0.001 transformed for normality. Tukey tests and Bonferroni-corrected custom tests were used for post hoc comparisons. Peak temperature preference was determined by the maximum amount of time spent at a specific temperature. Both group size (<i>p</i> = 0.001) and weight category (<i>p</i> < 0.001) influenced the thermal location choice of pigs. Individual pigs preferred 30.31 °C, which differed from a group of 2 (20.0 °C: <i>p</i> = 0.003) and 4 pigs (20.0 °C: <i>p</i> < 0.001). The peak temperature preference of the small pigs (30.2 °C) differed from the large pigs (20.0 °C: <i>p</i> < 0.001) but did not differ from the medium-sized pigs (28.4 °C: <i>p</i> > 0.05). Overall, heavier pigs and larger groups preferred cooler temperatures. |
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| id | doaj.art-ce744451d63846eb9585550bfefc246b |
| institution | Directory Open Access Journal |
| issn | 2076-2615 |
| language | English |
| last_indexed | 2024-03-10T11:18:27Z |
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| spelling | doaj.art-ce744451d63846eb9585550bfefc246b2023-11-21T20:14:54ZengMDPI AGAnimals2076-26152021-05-01115144710.3390/ani11051447One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg)Lindsey A. Robbins0Angela R. Green-Miller1Jay S. Johnson2Brianna N. Gaskill3Department of Animal Sciences, Purdue University, West Lafayette, IN 47906, USADepartment of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IN 61801, USAUSDA-ARS, Livestock Behavior Research Unit, West Lafayette, IN 47906, USADepartment of Animal Sciences, Purdue University, West Lafayette, IN 47906, USAHousing pigs within their thermal comfort zone positively impacts productivity and performance. However, fundamental information on behavioral thermoregulatory responses of individual and group-housed pigs is meager. As a gregarious species, pigs prefer to be near one another, touching and often huddling. As pigs huddle together, they decrease their heat loss to the environment by decreasing exposed surface area and increasing mass. Additionally, pigs gain weight rapidly as they age. As an individual grows, their ability to withstand lower temperatures increases. We hypothesized that group size would alter pig thermal preference and that thermal preference would change based upon body weight. Thirty-six groups of pigs (n = 2 pigs/group) were tested in a factorial design based on group size (1, 2, or 4) and weight category (small: 5.20 ± 1.15 kg; medium: 8.79 ± 1.30 kg; and large: 13.95 ± 1.26 kg) in both sexes. Treatment groups were placed inside a chamber with a controlled thermal gradient (4.6 m × 0.9 m × 0.9 m; L × W × H) that ranged in temperature from 18 to 30 °C. Pigs habituated to the gradient for 24 h. The following 24 h testing period was continuously video recorded and each pig’s location during inactivity (~70% daily budget) within the thermal apparatus was recorded every 10 min via instantaneous scan sampling. Data were analyzed using a GLM and log10 + 0.001 transformed for normality. Tukey tests and Bonferroni-corrected custom tests were used for post hoc comparisons. Peak temperature preference was determined by the maximum amount of time spent at a specific temperature. Both group size (<i>p</i> = 0.001) and weight category (<i>p</i> < 0.001) influenced the thermal location choice of pigs. Individual pigs preferred 30.31 °C, which differed from a group of 2 (20.0 °C: <i>p</i> = 0.003) and 4 pigs (20.0 °C: <i>p</i> < 0.001). The peak temperature preference of the small pigs (30.2 °C) differed from the large pigs (20.0 °C: <i>p</i> < 0.001) but did not differ from the medium-sized pigs (28.4 °C: <i>p</i> > 0.05). Overall, heavier pigs and larger groups preferred cooler temperatures.https://www.mdpi.com/2076-2615/11/5/1447thermal preferencepigsthermal comfort zonesocial aggregation |
| spellingShingle | Lindsey A. Robbins Angela R. Green-Miller Jay S. Johnson Brianna N. Gaskill One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg) Animals thermal preference pigs thermal comfort zone social aggregation |
| title | One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg) |
| title_full | One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg) |
| title_fullStr | One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg) |
| title_full_unstemmed | One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg) |
| title_short | One Is the Coldest Number: How Group Size and Body Weight Affect Thermal Preference in Weaned Pigs (3 to 15 kg) |
| title_sort | one is the coldest number how group size and body weight affect thermal preference in weaned pigs 3 to 15 kg |
| topic | thermal preference pigs thermal comfort zone social aggregation |
| url | https://www.mdpi.com/2076-2615/11/5/1447 |
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