The impacts of viral infection and subsequent antimicrobials on the microbiome-resistome of growing pigs

Microbiome

Table 1 Experimental design of control and treatment protocols for PRRSv challenge and antimicrobial treatments

Treatment group^a	PRRSv challenge	Antimicrobial exposures
Treatment group^a	PRRSv challenge	Individual pigs	In-water	In-feed	UDD^b
Minimal (N=36)	None/negative	As-needed to treat disease (penicillin G procaine or lincomycin HCl)	None	None	15
Moderate (N=36)	Experimentally-infected (2×10^3.5 TCID50 of a PRRSv 1-7-4 field isolate, intramuscularly)	As-needed to treat disease (penicillin G procaine or ceftiofur crystalline free acid)	Pulmotil® AC (tilmicosin phosphate, 250 mg/mL) for 5 days, starting 5 days post-PRRSv challenge	None	238
Intensive (N=36)	Experimentally infected (2×10^3.5 TCID50 of a PRRSv 1-7-4 field isolate, intramuscularly)	EXCEDE® (ceftiofur crystalline free acid, 5 mg/mL) to every pig, starting 7 days post-PRRSv challenge	Pulmotil® AC (tilmicosin phosphate, 250 mg/mL) for 5 days, starting 5 days post-PRRSv challenge	Chlortetracycline (400g/ton) and tiamulin, (35g/ton) for 14 days, starting 13 days post-PRRSv challenge	946

^aAll groups received modified live PRRSv vaccine (Ingelvac PRRS® MLV, Boehringer Ingelheim Vetmedica Inc., 2mL/pig) 10 days post-weaning
^bUsed daily doses were calculated as the total number of pig-days of treatment summed across all active ingredients; chlortetracycline and tiamulin were defined as a combined product as one of the treatments [41]

ISSN: 2049-2618