It has been shown that the jejunum represents the most important site for the nutrient’s absorption in several species. However, in pigs, this information seems to be controversial and limited information are available about differences in intestinal physiology between female and castrated male pigs. The trans-epithelial electrical resistance (TEER) and the active uptake of L-glutamate (L-Glu), L-arginine (L-Arg), L-methionine (L-Met) and D-glucose (D-Glu) in the jejunum and ileum of female (n = 5) and castrated male (n = 7) pigs fed a protein-restricted grower and finisher diet (128 and 112 g of crude protein/kg dry matter) were investigated. The intestine segments were collected at slaughter and mounted in Ussing chambers. Results were further investigated by protein expression analysis of the D-Glu transporter Sodium-dependent Glucose Transporter 1 (SGLT1) and using serum creatinine, non-esterified fatty acids (NEFAs) and serum glucose concentrations measurements as indicators of muscle mass deposition and metabolic status of the animals. A linear mixed-effects regression (Lme4) model was used for data analysis. Independent of sex, the uptake of both L-Met and D-Glu was higher (p < 0.001) in the ileum than in the jejunum (2.1- and 3.6-fold increases, respectively). The L-Arg uptake was higher (p = 0.001) in females compared to castrates (1.9-fold increase). No significant differences were observed between the segments in the SGLT1 protein expression, regardless of sex. Serum measurements were also not significantly different between the female and castrates. This study suggests that the ileum has an important role in the active uptake of amino acids and D-Glu uptake and differences exist between female and castrated finishing pigs.
