Effects of pen location on thermoregulation and growth performance in grow-finish pigs during late summer

Authors: KPODO, KOUASSI - Purdue University; DUTTLINGER, ALAN - Purdue University; Johnson, Jay

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2019
Publication Date: 3/23/2019
Citation: Kpodo, K.R., Duttlinger, A., Johnson, J.S. 2019. Effects of pen location on thermoregulation and growth performance in grow-finish pigs during late summer. Translational Animal Science. https://doi.org/10.1093/tas/txz033.
DOI: https://doi.org/10.1093/tas/txz033

Interpretive Summary: In intensive production systems, pigs are reared in confinement to provide optimal environmental conditions and maximize welfare and productivity. However, despite these attempts, increasing summer temperatures and heat waves can overwhelm cooling systems in barns and subject pigs to heat stress conditions. Heat stress negatively impacts reproductive efficiency, growth rate, and health resulting in economic losses despite advances in barn cooling technologies. In addition, variation in either ambient temperature, relative humidity or airflow creates microenvironments in swine barns. Although numerous reports have evaluated the direct effects of heat stress on production losses and temperature regulation, few have investigated the impact of microenvironments on swine thermoregulation and productivity. Therefore, the study objective was to ascertain the existence of microclimates in grow-to-finish barns and characterize their impacts on swine productivity and temperature regulation during late summer. It was determined that microclimate variations in growing-finishing barns caused by air flow differences, can negatively affect swine thermoregulation and performance. Specifically, pigs housed in pens with a reduced air flow had increased body temperature and a reduction in feed efficiency. These data may have implications towards ventilation system management within swine facilities and the impact of pen-to-pen environmental variation on thermoregulation and productivity of pigs during hot summer months.

Technical Abstract: The effects of pen location on swine thermoregulation and productivity were determined over six weeks during late summer. A total of 128 mixed sex pigs [Duroc x (Landrace x Yorkshire)] were randomly assigned to 16 pens in two grow-finish barns [n = 8 pens/barn; 57.4 ± 1.3 kg initial body weight (BW)]. Pen locations were determined based on orientation to ventilation fans and air inlets. Internal pens (IP; n = 4/barn) were in direct line of sight between the fans and air inlets while peripheral pens (PP; n = 4/barn) were located 0.70 ± 0.29 m from a fan. Two sentinel gilts per pen were selected and vaginal temperature (TV) was measured in 10 min intervals using TV data loggers. Additionally, skin temperature (TS) was measured with an infrared camera and respiration rate (RR) was measured by counting flank movements of the sentinel gilts twice daily (0800 and 1500 h). Pen airflow was measured twice daily (0800 and 1500 h) with an anemometer. Individual pen ambient temperature (TA) and relative humidity (RH) were recorded daily in 10 min intervals. Average daily gain (ADG) and average daily feed intake (ADFI) were determined bi-weekly. Data were analyzed using PROC MIXED in SAS 9.4. Although airflow was reduced overall (P = 0.04; 11%) in PP compared to IP, no differences (P > 0.56) in TA (27.53 ± 1.73°C) or RH (68.47 ± 5.92%) were detected. An overall increase (P < 0.03) in TV (0.23°C), minimum TV (0.18°C), and maximum TV (0.29°C) was detected in PP versus IP housed pigs. Similarly, from 0800-1900 h and 2000-0700 h, TV was greater overall (P < 0.02; 0.22 and 0.25°C, respectively) in PP compared to IP housed pigs. An overall decrease in TS (P = 0.04) was observed in PP (37.39 ± 0.14°C) compared to IP (37.61 ± 0.14°C) housed pigs. No RR differences (P > 0.64; 76 ± 4 bpm) were detected with any comparison. While no ADG or ADFI differences were detected (P > 0.14; 0.75 ± 0.02 kg/d and 2.26 ± 0.07 kg/d, respectively), feed efficiency was decreased (P = 0.04; 6%) in PP compared to IP housed pigs. In summary, pigs located in PP had greater body temperature and reduced feed efficiency despite similarities in TA and RH between all pens. These data have implications towards management of ventilation systems within swine facilities and the impact of pen-to-pen environmental variation on thermoregulation and productivity of pigs during hot summer months.