Effect of amino acid blend as alternative to antibiotics for growing pigs

This study aimed to evaluate the effect of supplementing arginine (Arg) + glutamine (Gln) replacing antibiotics on performance, immune response, and antioxidant capacity of pigs in the growing phase. One hundred and fifty 63-d-old pigs with initial body weight (BW) of 25.0 ± 1.46 kg were distributed in a randomized block design, with three treatments and ten replicates. The three diets were control; antibiotic, control + 100 mg/kg tiamulin and 506 mg/kg oxytetracycline; amino acid, control + 10 g/kg Arg and 2 g/kg Gln. Dietary treatments were fed from 63 to 77 d. Following the treatment period, all pigs were fed the control diet from 77 to 90 d. Data were analyzed using GLIMMIX and UNIVARIATE in SAS 9.4. From 63 to 70 d, pigs fed diets with antibiotics had improved (P < 0.05) average daily feed intake (ADFI), average daily weight gain (ADG), gain to feed ratio (G:F), and 70 d BW compared to those fed control or amino acid diets. From 70 to 77 d, including antibiotics in the diet increased (P < 0.05) ADG and 77 d BW. From 77 to 90 d, pigs fed the amino acid diet had greater (P < 0.05) ADG and ADFI than those fed an antibiotic diet. From 63 to 90 d, although pig performance was not affected (P > 0.05), growth curve of pigs fed the antibiotic diets was different (P < 0.05) from those fed the control and amino acids diets. At 70 d, serum tumor necrosis factor-α and diamine oxidase (DAO) were lower (P < 0.05) in pigs fed the antibiotic diet than the control diet, and pigs fed the amino acid diet had intermediate results. Ferric reducing antioxidant power (FRAP) was lower (P < 0.05) in pigs fed the amino acid diet than the antibiotic diet, and pigs fed the control diet had intermediate results. At 70 and 77 d, serum urea nitrogen was higher (P < 0.05) in pigs fed the amino acid diet. At 77 d, DAO and serum immunoglobulin G was lower (P < 0.05) in pigs fed the antibiotic diet. FRAP was lower (P < 0.05) in pigs fed the amino acid and control diets. Serum malondialdehyde was higher (P < 0.05) in pigs fed the amino acid diet than those fed the control diet, and pigs fed the antibiotic diet had intermediate results. At 90 d, antibiotics or amino acids did not affect (P > 0.05) serum parameters. Amino acid blend supplementation at the selected doses in this study did not positively affect growing pigs. Although from 63 to 77 d, antibiotics improved performance, when considering the overall study period, growing pigs did not benefit from a diet containing antibiotics.