Evaluation of dietary selenium sources and levels on growth performance, carcass characteristics, selenium concentrations, and blood parameters of growing-finishing pigs

Selenium (Se) is an essential trace mineral that play an important role in physiological and biochemical responses by regulating the antioxidant system. Dietary Se is provided as a nutritional supplement to livestock diets in inorganic (ISe) or organic (OSe) form and has different bioavailability to animals. However, the comparison of the effects of dietary Se in different forms and levels of bioavailability are still limited. Therefore, this study was conducted to evaluate the effects of dietary Se sources and levels on growth performance, carcass characteristics, proximate composition of pork loin, Se concentrations, and blood parameters of growing-finishing pigs. In a randomized completely block design (block = initial body weight and sex), 160 pigs (28.17 ± 3.03 kg of body weight) were allotted to five dietary treatments (4 pigs/pen; 8 replicates/treatment) and fed for 14 weeks. Dietary treatments were 1) a non-Se-fortified diet based on corn and soybean meal provided as control (CON), 2) CON + 0.3 ppm ISe (ISe3), 3) CON + 0.5 ppm ISe (ISe5), 4) CON + 0.3 ppm OSe (OSe3), and 5) CON + 0.5 ppm OSe (OSe5). Data and sample collections were conducted at the specific time points during the study. Pigs fed dietary OSe tended to have an increased (<italic>p</italic> &lt; 0.10) gain to feed ratio in the grower phase compared with those fed dietary ISe. In addition, dietary OSe increased (<italic>p</italic> &lt; 0.05) hot carcass weight compared with dietary ISe. In contrast, dietary ISe increased (<italic>p</italic> &lt; 0.05) crude protein content of pork loin compared with dietary OSe. Se concentrations in the kidney and pork loin were higher when the dietary Se source was OSe (<italic>p</italic> &lt; 0.05) and increased with increasing dietary Se level (<italic>p</italic> &lt; 0.05). In the finisher phase, serum total protein, calcium, inorganic phosphorus, magnesium, and creatinine concentrations increased with increasing dietary Se level (<italic>p</italic> &lt; 0.05). In conclusion, our study verified that dietary ISe and OSe each affected crude protein content of pork loin and tissue Se concentrations, respectively. Furthermore, blood biochemical parameters were modulated by prolonged intake with increased levels of dietary Se, regardless of the Se source.