Fig. 2.

Effects of essential oils and protease on the serum cytokine concentrations of weaned pigs. (A) TNF-α concentration; (B) IL-1β concentration. CON = pigs fed basal diet; EO = pigs fed basal diet supplemented with 300 mg/kg essential oils; PRO = pigs fed basis diet supplemented with 500 mg/kg protease; EO + PRO = pigs fed basal diet with 300 mg/kg essential oil and 500 mg/kg protease; EO × PRO = interaction between EO and PRO; IL-1β = interleukin 1β; TNF-α = tumor necrosis factor-α. Values are means and standard errors represented by vertical bars (n = 8). ^a,b Means without a common letter differ (P < 0.05).