摘要Background Commercial diets are frequently formulated to meet or exceed nutrient levels including those of lim-iting essential amino acids(AA)covering potential individual variations within the herd.However,the provision of dietary excess of AA,such as Lys,may lead to reduced appetite and growth in pigs.The mechanisms modulat-ing these responses have not been extensively investigated.This study evaluated the effect of Lys dietary excesses on performance and satiety biomarkers in post weaning pigs.Methods Twenty-four pigs aged 21 d and weighing 6.81±0.12kg(mean±SEM)were individually housed and offered 1 of 4 dietary treatments for 3 weeks:a diet containing a standardized ileal digestible Lys reaching 100％(T0),120％(T1),150％(T2)or 200％(T3)of the NRC(2012)requirements.At the end of the experiment,blood samples from the cephalic vein of theT0 and T3 groups were obtained for AA analysis.In addition,primary intestinal cultures from T0 pigs were used,following their humane killing,to evaluate the effect of Lys on gut hormone secretion and AA sensors gene expression under ex vivo conditions.Results Feed intake was linearly reduced(P＜0.001)and the weight gain to feed ratio reduced(P＜0.10)with increased dietary levels of Lys during the third-and first-week post weaning,respectively.Cholecystokinin con-centration(P＜0.05)and the metabotropic glutamate receptor 1 and the solute carrier family 7 member 2(P＜0.10)gene expression was enhanced in proximal jejunum tissues incubated with Lys at 20mmol/L when compared to the control(Lys 0mmol/L).Plasma Lys and Glu(P＜0.05)concentration increased in theT3 compared to T0 pigs.In contrast,plasma levels of His,Val,Thr,Leu(P＜0.05)and Gin(P＜0.10)were lower inT3 thanT0 pigs.Conclusion The present results confirm that excess dietary Lys inhibits hunger in pigs.Moreover,the results provide evidence of pre-and post-absorptive mechanisms modulating these responses.Lys dietary excesses should be nar-rowed,when possible,to avoid negative effects of the AA on appetite in pigs.