Effects of Facility System Design on the Stress Responses and Market Losses of Market Weight Pigs During Loading and Unloading1

The objective of this study was to determine the effect of 2 grow-finish swine facility system designs and presorting on the stress responses and incidence of nonambulatory and dead pigs at the time of loading and unloading market pigs. A total of 5,901 pigs (n = 33 loads) were used in a randomized complete block design. The new facility system design (NFSD) had 192 pigs/pen, and internal swing gates were used to manually presort market weight pigs on the day before loading. The smaller traditional facility system design (TFSD) had 32 pigs/pen with no presorting. During loading, facility system design and presorting were randomly assigned to trailer decks. The time required to load a trailer deck was recorded by facility system design and presorting. Data were analyzed using generalized linear mixed model methodology, and loading time was analyzed using mixed model procedures. Loading time differed (P = 0.007) between facility system design and presorting, with TFSD taking longer to load compared with NFSD. The NFSD with presorting had lower (P < 0.05) percentages of open-mouth breathing, skin discoloration, and muscle tremors during loading and unloading compared with TFSD with no presorting. The NFSD had fewer (P = 0.006) dead pigs on arrival and fewer-total nonambulatory pigs (P = 0.041) and total losses (P = 0.003) at the plant compared with TFSD. In summary, the NFSD with presorting reduced physical signs of stress during loading and unloading and reduced total losses at the plant by 66% compared with losses attained when pigs were loaded from the TFSD with no presorting.