Evaluation of the effect of the indoor environment on the physiological responses of early-gestation sows in a commercial house in China

Yangyang Li; Tong Li; Bin Shang; Yang Zhao; Xiuping Tao; Feng Peng; Xiaojun Zou; Sixin Zhang

doi:10.3389/fvets.2023.1178970

Evaluation of the effect of the indoor environment on the physiological responses of early-gestation sows in a commercial house in China

Front Vet Sci. 2023 Jun 1:10:1178970. doi: 10.3389/fvets.2023.1178970. eCollection 2023.

Authors

Yangyang Li¹, Tong Li², Bin Shang¹, Yang Zhao³, Xiuping Tao², Feng Peng⁴, Xiaojun Zou⁴, Sixin Zhang⁵

Affiliations

¹ Key Laboratory of Energy Conservation and Waste Management in Agricultural Structures, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.
² Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China.
³ Department of Animal Science, The University of Tennessee, Knoxville, Knoxville, TN, United States.
⁴ Henan Zhumei Swine Breeding Co., Ltd., Zhumadian, China.
⁵ Zhengyang Pig Farm in Henan Province, Zhumadian, China.

Abstract

Objective: The environment influences the sow's health and physiology during gestation. This study was conducted to evaluate indoor environmental parameters and physiological responses of early-gestation sows and investigate the possible methods for assessing the thermal environment in commercial houses.

Methods: A total of 20 early-gestation sows (commercial purebred Yorkshire) with an average body weight of 193.20 ± 3.62 kg were used for this study in winter, spring, summer, and autumn. The indoor environment parameters comprising dry-bulb temperature (T_db), relative humidity (RH), and carbon dioxide (CO₂) were recorded in 30-min intervals. Physiological parameters including heart rate (HR) and respiration rate (RR) of sows were also measured every 30 min. Wet-bulb temperature (T_wb) was calculated using T_db, RH and atmospheric pressure was recorded at a nearby weather station.

Results: The average indoor T_db and RH were 12.98 ± 2.03°C and 80.4 ± 6.4% in winter, 18.98 ± 2.68°C and 74.4 ± 9.0% in spring, 27.49 ± 2.05°C and 90.6 ± 6.4% in summer, and 17.10 ± 2.72°C and 64.5 ± 10.9% in autumn. A higher average concentration of CO₂ was observed in winter (1,493 ± 578 mg/m³) than in spring (1,299 ± 489 mg/m³), autumn (1,269 ± 229 mg/m³), and summer (702 ± 128 mg/m³). Compared with the HR and RR in the optimum environment, high RH in the house led to a significant decrease in both HR and RR (P < 0.05). In addition, a significant decline in HR was also obtained at high temperatures (P < 0.05). A temperature humidity index (THI), THI = 0.82 × T_db + 0.18 × T_wb, was determined for early-gestation sows, and the THI thresholds were 25.6 for HR. The variation in THI in summer showed that heat stress still occurred under the pad-fan cooling system.

Conclusion: This study demonstrated the critical significance of considering physiological responses of early-gestation sows in commercial houses and THI thresholds. We recommend that much more cooling measures should be taken for early-gestation sows in summer.

Keywords: index; physiology; sow; temperature humidity index; threshold.

Grants and funding

The co-authors appreciate the support of staff from the pig-breeding farm during the experiment. This research was supported by the Shanghai Agriculture Applied Technology Development Program, G20190301 and the Agricultural Science and Technology Innovation Program, CAAS-XTCX2016011-01.