## 2 Materials and Methods
### Sampling and Measurements  
Individual pig weights were measured at the start of the study, as well as the 4 th, 8 th, and 13 th week of the experimental period. The study determined the average daily gain (ADG, kg). Also, average daily feed intake (ADFI, kg) and gain-to-feed ratio (G: F) were determined by the amount of feed ingests and scraps (pen basis). To evaluate the digestibility of dry matter (DM), energy (E), and nitrogen (N), 2 g/kg of chromium oxide (Cr\({}_{2}\)O\({}_{3}\)) was added to the diet. This marker was introduced for fecal collection for seven days prior to the 4 th week, 8 th week, and 13 th week of the study. Samples of the feed were collected and preserved on a weekly basis. In the 5 th and 10 th weeks, these samples were combined to create a demonstrative composite sample. Fecal samples were randomly collected from at least two pigs in each pen, consisting of one male and one female, resulting in a total of 14 pigs per treatment by rectal massage; these samples were combined by pen. According to the respective treatment conditions, all feed and fecal samples were dried at 70 \({}^{\circ}\)C for 72 h and then finely ground to a texture that enabled them to pass through a 1 mm screen. Following the guidelines of the AOAC [14], the nutrient digestibility of DM, N, and GE and chromium absorption in feed and fecal samples were analyzed following the method used by [PERSON] et al. [15]. Regarding the blood parameters, two pigs were chosen at random from each pen (one male and one female, 14 pigs/treatment). They underwent blood collection through jugular venipuncture in the 4 th week, 8 th week, and 13 th week of the study. The serum was separated through centrifugation at 3000 rpm for 20 min, at 3000\(\times\)\(g\) at a temperature of 4 \({}^{\circ}\)C, and subsequently preserved at \(-\)20 \({}^{\circ}\)C until further analysis. Thereafter, an assessment was conducted for epinephrine, norepinephrine, cortisol, and IgG levels. The quantification of serum epinephrine and norepinephrine levels was accomplished by employing an ion-exchange purification technique, followed by high-performance liquid chromatography (HPLC) and electrochemical detection, in accordance with the methodology outlined by [PERSON] and [PERSON] [16]. In brief, the samples were placed in cationic columns and a boric acid elution procedure was used to separate the catecholamines (epinephrine and norepinephrine). The eletents underwent analysis through high-performance liquid chromatography (HPLC) with electrochemical detection at an oxidizing potential of +0.65 V. The within-assay coefficient of variation (CV) for epinephrine and norepinephrine was recorded at 6.5% and 7.0%, respectively. The inter-assay CVs for epinephrine and norepinephrine were 11.6% and 7.1%, respectively. The level of cortisol in serum was determined by a commercial ELISA kit. The serum IgG levels were assessed using an automatic biochemistry blood analyzer (Hitachi 747, Hitachi, Tokyo, Japan). Backfat thickness (BFT) and lean meat percentage were measured from each pig in the 4 th, 8 th and 13 th week using a real-time ultrasound instrument (Pig-log 105, SFK Technology, Herlev, Denmark). Upon completion of the study, all pigs were transported to a nearby commercial slaughterhouse and processed using standard slaughtering techniques. The carcasses were cooled at a temperature of 2 \({}^{\circ}\)C for a duration of 24 h. Subsequently, a 2.54 cm thick section of the longissimus muscle (LM) was obtained by making a perpendicular cut at the 10 th and 11 th rib. Meat samples were selected at random from each pen, involving two pigs from each pen, comprising one gilt and one barrow, with a total of 14 pigs per treatment.