Factors associated with fatigued, injured, and dead pig frequency during transport and lairage at a commercial abattoir1

Abstract

The objective of this study was to identify environmental and management factors that are associated with the frequency of fatigued, injured, and dead pigs on arrival and in resting pens during lairage at a commercial Midwest abattoir. The terms transport losses or total losses refer to pigs that die or become nonambulatory at any stage of the marketing process. In this study, fatigued, injured, and dead pigs were summed into a variable termed total losses. Relative humidity (%), temperature ( degrees C), wind speed (m/s), and dew point ( degrees C) data were collected on 12,333 trailer loads of pigs. Week, sort from barn (first or third pig removal from barn), farm, normal vs. split load type (from 1 or multiple barns), load crew, driver, trailer, and wind direction were used as fixed effects in the model for the analysis of losses per load using generalized mixed models for Poisson distributions. Seven temperature-humidity indices (THI) were calculated and compared as model covariates. Load time per pig, trailer density (pigs per trailer x average BW/trailer space; kg/m(2)), wait time before unloading at the abattoir, and wind speed were used as model covariates. The log of the number of hogs per trailer was used to standardize the response variable. The linear covariate density accounted for the greatest portion of variance (based on F-value) followed by the fixed effect sort from barn, the fixed effect load type (pigs from 1 or multiple barns within a farm), load time per pig linear covariate, and THI. Pigs transported to the abattoir from June through July experienced fewer losses (P < 0.001) when compared with pigs that were transported from November through December. Keeping other factors constant, the log of total losses (%) per load increased by 0.0102x + 0.000541x(2) per unit of THI and 0.0191 kg/m(2) of density. Similarly, of 9 farms, the poorest-performing farm in regards to total loss percentage experienced 0.93% more losses per load when compared with the farm with the least loss percentage. This study demonstrates that multiple environment and management factors influence the incidence of market hog transport losses.