Survey of classical swine fever immunization status in pigs in large-scale pig farms and optimization of primary vaccination in piglets.

In order to investigate immunization schedules of classical swine fever(CSF) in large-scale pig farms,and to evaluate the immune status,seven large-scale pig farms in Hubei province were selected.Pigs were divided into the sows,the boars,the prepubertal gilts,the breast-feeding piglets(about 0-30 days),the nursing piglets(about 31-60 days old) and the growing pigs(above 61 days old).In each herd,blood were collected from 5%-8% of pigs and antibody titers were tested.Results showed that the qualification rate of all immunized herds were 99.55%,96.43%,99.22%,89.88%,81.68% or 78.64%,and different immunization schedule induced different immune status.Overall,the nursing piglets and the growing pigs were the weakest of all pig groups.Piglets received primary vaccination on day 14,21,28 and 35 after birth based and the antibody examined 7 and 14 days after immunization.Results indicated that 28 days after birth was the best time for primary immunization.This study provides valuable references to the control of CSF.