Impact of a porcine epidemic diarrhea outbreak on swine productivity in Japan: a retrospective cohort study

YAMANE, Itsuro; YAMAZAKI, Hisanori; ISHIZEKI, Sayoko; WATANABE, Yugo; OKUMURA, Hanako; OKUBO, Mitsuharu; KURE, Katsumasa; HAYAKAWA, Yuiko; FURUKAWA, Makoto; OOI, Munetaka; MIZUKAMI, Yoshihiro; ITO, Mitsugu

The mean values of all the parameters differed significantly at different time points, so the time factor was significantly associated with all the variables investigated in this study. The expression as "interaction between time and groups was significant" means some groups (S-PED-positive and L-PED-positive groups) had significantly lower or higher values for these variables at specific time points compared with the other group (PED-negative group). For example, the average preweaning mortality in April-June was significantly lower in the PED-negative group than in the L-PED-positive group, even though it did not differ among the groups at the other sampling times, which can be explained by the interaction between time and group. We observed significant time-group interactions for PRWM, POWM, PWL and MP, in that the values for these parameters were significantly lower in specific groups (S-PED-positive and L-PED-positive) than in the other group (PED-negative) at specific time points.