Linear models fitted to data of milk synthesis efficiency (I), 4% FCM synthesis efficiency (II), milk fat synthesis efficiency (III), and milk protein synthesis efficiency (IV), which are expressed asy, in response to concentrations of IL-8 (expressed asx) in mammary gland venous plasma of dairy cows. I, y = −0.0022x + 1.457 (R2 = 0.0477, r = −0.2184, SE = 0.1840, P = 0.2462, n = 30); II, y = −0.0056x + 1.746 (R2 = 0.1879, r = −0.4335, SE = 0.2207, P = 0.0167, n = 30); III, y = −0.0236x + 7.037 (R2 = 0.1595, r = −0.3394, SE = 1.031, P = 0.0288, n = 30); IV, y = −0.0149x + 5.255 (R2 = 0.1622, r = −0.4027, SE = 0.6458, P = 0.0273, n = 30).