No pig may leave the holding before the negative results of the serological tests are available; if none of the pigs has developed antibodies against African swine fever virus , full repopulation may then take place;. This sentence is hard to understand. A simpler version with equivalent meaning is the following:
No pig may leave the farm before the negative results of the serological tests are available . If no antibodies against the ASF virus have developed in any of the pigs , they can be fully replenished .