An experiment was conducted to evaluate the expression of insulin-like growth factor-I (IGF-I) and IGF-binding proteins (IGFBPs -II and -III) in response to a 10% inclusion of caramel plant wastewater (CPWW) in weaning pig diets; the objective was to assess associations between those growthrelated proteins to feed intake (Fl) and body weight gain (BWG). Sixteen purebred Landrace piglets were randomly distributed among eight pens (a gilt and boar per pen) and assigned to one of two treatments: 0% (control) and 10% inclusion of CPWW. During four consecutive weeks, live weight and Fl were recorded. Blood samples were drawn by jugular venipuncture during the first, second, and third weeks of the experiment and serum levels of IGF-I, IGFBP-II and IGFBP-III were determined. Feed intake, BWG and feed efficiency (FE) were not affected (P > 0.05) by the addition of 10% CPWW tothe diet, nor was animal health status visibly affected. Serum IGF-I levels were higher in control animals (P < 0.05) and increased from d 14 to d 28 of the experimental period (P < 0.05). Weekly increases were observed for IGFBP- III (P < 0.05) whereas IGFBP-II circulating levels decreased from d 14 to d 28 of the post-weaning test period. Simple correlation analysis revealed that there was a positive association between circulating levels of IGF-I and IGFBP-III (r = 0.88; P < 0.0001). However, the opposite was observed between these two and IGFBP-II (r = -0.84, P < 0.0001; r = -0.67, P < 0.0025, respectively). The changes observed in circulating levels of IGF-I, IGFBP-III and IGFBP-II were associated with weekly increases in Fl and BWG that occurred during the entire experimental period (P < 0.05).