Economic assessment of feed restriction or amino-acid deficiency during the pig fattening period The profitability of pig farms is influenced greatly by feed efficiency and carcass grading. The aim of this study was to assess the economic impact of two feeding strategies during the fattening period, compared to that of a control (T), which was ad libitum feeding with no amino-acid deficiency. The first strategy was ad libitum feeding with a three-phase sequence limited in amino acids (CA). The second strategy was restricted feeding at 85% of the ad libitum without amino-acid deficiency (RA). Each of the three feeding strategies was applied to 48 gilts and 48 barrows. Technical performances were estimated using a general linear model. Then, the feed conversion ratio (FCR) was standardized to the range of 30-120 kg. The lean meat percentage (LMP) was standardized to 120 kg. These criteria were input into a simulator (GT-DIRECT, "Calculate" module) to assess the economic feeding margin of each strategy. Two extreme economic contexts were considered using two assumptions for fattening feed price (HIGH and LOW). The CA margin was lower than that of T, by € 3.4 and € 5.6 per pig produced for the LOW and HIGH feed price contexts, respectively. The predominant effect was that of feed price, which penalized feed cost due to an FCR higher by 0.18 units. The RA margin was also lower than that of T, by € 0.7 and € 2.8 per pig produced for the LOW and HIGH feed price contexts, respectively. The higher FCR (+0.17 kg/kg) induced an increase in feed cost which was compensated only partially by the increase in output due to the better LMP ratio (+1.5 percentage point). Thus, meeting amino-acid needs and mastering feed restriction remain essential.