Survival of Ascaris suum and Ascaridia galli eggs in liquidmanure at different ammonia concentrations andtemperatures

Summary in the original language of the document

tEggs of Ascaris suum from pigs are highly resistant and commonly used as a conservativeindicator of pathogen inactivation during slurry storage. Eggs of Ascaridia galli, the poultryascarid, are also known to be highly resistant but the suitability as an indicator of pathogeninactivation has never been tested. Pig slurry has to be stored for several months to inac-tivate pathogens but chemical treatment of slurry may reduce this time. The suitability ofA. galli as an indicator of slurry sanitation was tested by comparing the survival of eggsof A. suum and A. galli in pig slurry. In addition, the effect of urea treatment on inactiva-tion of ascarid eggs in relation to storage time was also tested. Nylon bags with 10,000eggs of either species were placed in 200 ml plastic bottles containing either urea-treated(2%) or untreated pig slurry for up to 120 days at 20◦C, 6 days at 30◦C, 36 h at 40◦C or2 h at 50◦C. At all the temperatures in both slurry types, A. galli eggs were inactivated ata significantly faster rate (P < 0.05) compared to A. suum eggs. For each 10◦C raise in tem-perature from 20◦C, T50(time needed to inactivate 50% of eggs) for both types of eggswas reduced markedly. At all temperatures, viability of eggs of both species was signifi-cantly higher (P < 0.05) in untreated slurry compared to urea-treated slurry except A. gallieggs at 20◦C where no significant difference was detected. In untreated slurry, the levelsof pH (6.33–9.08) and ammonia (0.01–1.74 mM) were lower (P < 0.0001) compared to thatof urea-treated slurry (pH: 8.33–9.28 and ammonia 1–13 mM). The study demonstratedthat A. galli eggs are more sensitive to unfavourable conditions compared to A. suum eggs.The use of A. galli eggs as hygiene indicator may thus be suitable to assess inactivation ofpathogens that are more sensitive than A. galli eggs. Addition of urea may markedly reducethe storage time of slurry needed to inactivate A. suum and A. galli eggs.