Effect of Environmental Factors on the Frequency of Fatigued, Injured, and Dead Pigs at a Commercial Abattoir

The objective of this study was to identify the effects of harvest week, weather, and transport conditions that influence the frequency of fatigued, crippled, and mortalities pigs, often termed defects, on arrival and in the resting pen at a commercial abattoir. Relative humidity, temperature, wind speed, and dew point were collected for trailer loads of pigs (n = 10,993 loads) from May 2005 to April 2006. A temperature-humidity index was calculated (NOAA, 1976) and used as a model covariate along with load time per pig, trailer density, and pig rest time. Week, pull, farm, split or normal load type, load crew, driver, trailer, wind direction, and wind speed were used as fixed effects in the model for the analysis of the defect percentage per load using GLIMMIX procedures (SAS). The linear covariate density accounted for the greatest portion of variance (based on F value) followed by pull from barn, the linear covariate minutes of rest before harvest, fixed effect load type, load time per pig linear covariate, and the THI quadratic covariate. Pigs transported to the abattoir during summer months (June – August) resulted in fewer defects (P<0.001) than pigs transported during winter months (December – February). Assuming other factors are held constant, the log of percentage of defects per load increased by 0.0083x + 0.000461x2 per unit of temperature-humidity index and 0.019 per unit of density. The results of this study demonstrate that multiple factors influence and could be modified to reduce the percentage of defects per load of finishing pigs.