The detaset describes the response of a suckler cow in terms of plasma non-esterified fatty-acids (NEFA) concentrations, that was exposed to a feed restriction that consisted in the reduction of net energy requirements by 50%. The dataset has two columns, one for time (t) in days (d) and another column for plasma NEFA concentrations (g·L-1). The feed restriction started at t = 1 d and lasted untill t = 4 d. Negative values for t represent the pre-challenge period.