Airway Metrics, Anatomy and Growth Performance of Pigs Reared Indoors and Outdoors

While the swine industry has made incredible strides to improve ventilation, air quality in confinement buildings remains an issue. The goal of this study is to characterize correlation between large airway metrics and growth performance in piglets reared indoors and outdoors on pasture. Three experimental trials were conducted: Trial 1 included three breed types that were strictly raised indoors, Tamworth X Berkshire, Berkshire X Berkshire and Hereford X Berkshire (n = 4-5 each). Trials 2 and 3 consisted of animals reared in both environments; trial 2 had 28 pigs (n = 14, indoor and n = 14, outdoor) and trial 3 had 48 pigs (n = 24, indoor and n = 24, outdoor). For trial 3, body weights were recorded weekly for seven weeks to adjust tracheal measure for body size. Total tracheal and lumen diameters were determined for all animals on trial. Histological evaluations were performed to evaluate potential differences among indoor and outdoor pig populations. One-way and two-way Analyses of Variance (ANOVA) were performed and LS means with the PDIFF option was used to separate means as applicable. Animals reared indoor shad significantly larger tracheal diameters and lumens compared to those reared outdoors (p-value<0.05). Outdoor animals had a larger variation of body weights than indoor animals; however, no correlation between tracheal measurements and body weights was present. Histological evaluation of airway sections revealed a 1.4 fold increase in the total population of goblet cells in tracheas of indoor pigs (p-value<0.0152) versus outdoor pig tracheas. Taken together, subtle differences may exist in airways of pigs reared indoors versus outdoors; however, airway distinctions do not appear to effect growth performance of piglets.