Table 2.

Inhibitory concentration fraction index (FICi) values of bioactive compounds interacting with antimicrobials showed synergism

Checkerboard	FICi
	UFV03	J
Tiamulin × Gut-A	0.2A	0.34A
Valnemulin × 7-Epic- Cu	0.56B	0.54B
Valnemulin × Gut-A	0.3A	0.4A
Enrofloxacin × 7- Epic	0.5A	0.55B
Enrofloxacin × 7-Epic- Cu	0.3A	0.3A

All other interactions tested did not show a synergistic effect, with interaction index indices in the range of 0.75 < FICi ≤ 2

^ATotal synergism

^BPartial synergism