Scientific Abstract
The finishing phase of pig production represents an area of opportunity in the swine industry. Feed accounts for the majority of costs at this stage of production. Impacts of indoor environment quality and management strategies have been highlighted individually in scientific literature. This study aimed to evaluate these factors on a large-scale field experiment under commercial conditions. Sixteen wean-finish barns in North Carolina of similar age and construction were monitored. All sites were within the same sow farm flow with 14 barns having a pig capacity of 880 and 2 barns with 1440 head capacity. Each barn was mechanically tunnel ventilated and had radiant tube heaters, standard dry feeders, and a shallow pit that was either pull-plug (12 barns) or flush type (4 barns). Barns were monitored for three turns of pigs, with the exception of site E being monitored for two turns. The same service technician and veterinarian serviced all sites. Sensors to measure temperature, relative humidity, and carbon dioxide were placed at the front and back of each barn to measure these parameters every 10 min. Ammonia was also recorded every 10 min in one barn per site and waste management system type, for six barns total. At week one and week 17 during the finishing period additional measurements of feed pan coverage, water flow rates, particulate matter, airspeeds, and pig health observations were collected. In week 17 for turns two and three oral fluids were collected via cotton ropes and tested for Influenza A, PEDV, PRRSV, and M. hyponeumoniae. One water quality sample was tested per site. Daily mortalities and pig treatments including vaccinations, NSAIDS, and antibiotics were recorded. A longitudinal generalized linear mixed model (GLMM) was developed to relate weekly mortality rates to measured conditions. Statistically significant factors were week after placement (p < 0.0001), proportion of barn fill capacity (p = 0.0019), season (p < 0.05), average relative humidity at the front of the barn (p < 0.0001), variation in relative humidity at the front of the barn (p < 0.0001), temperature difference from setpoint at the back of the barn (p < 0.0001), average (p = 0.0049) and variation (p = 0.0011) in CO2 at the front of the barn, variation in CO2 at the back of the barn (p < 0.0001), and a tendency for variation in temperature at the front of the barn (p = 0.052). Pigs placed during the Summer (June, July, August) had lower mortality compared to Winter (p <0.001), Spring (p < 0.001), and tended to have lower mortality compared to Fall (p = 0.0574). Spring placement groups had greater mortality compared to Fall (p < 0.0001) and Winter (p = 0.0110), but no differences were detected between pigs placed in Winter and Fall. The model had an R2 = 0.2372 and an RMSE of 0.38%. Ten percent of measured nipple water flow rates were below 1 L min-1. Respirable dust (< 2.5 µm) measurements were below the recommended OSHA 8 hour time weighted average limit for humans (5000 µg m-3) in 3.7% of measurements recorded, with no measurements for total dust (< 10 µm) above the recommended limit (15000 µg m-3). Results provide insight into quantitative relationships between environmental and management factors and finishing pig performance, highlighting opportunities for improved efficiencies.
