Effects of dietary supplementation with different levels of selenium yeast on growth performance, carcass characteristics, antioxidant capacity, and meat quality of Tan sheep

This study was conducted to evaluate the influence of dietary supplementation with different levels of selenium yeast (SeY) on growth performance, carcass characteristics, antioxidant capacity and meat quality of Tan sheep. Sixty-four (n = 64) five-month-old male Tan sheep with an initial body weight of 32 ± 1.95 kg (BW ± SD) were selected and randomly assigned to four treatments with 16 replicates of one sheep each. The four groups received a basal diet (0.16 mg Se/kg) supplemented with 28.94, 105.46, 258.51, 564.60 mg/kg SeY to final dietary selenium (Se) concentrations of 0.25 (Se0.25), 0.5 (Se0.5), 1.0 (Se1.0), or 2.0 (Se2.0) mg/kg for 60 days, respectively. The feed-to-weight gain ratio showed a quadratic significant change of first increasing and then decreasing with the increase of dietary SeY supplemental level (p<0.01). Dietary Se at >0.25 mg/kg markedly decreased the GR value of the sheep (p<0.05). Thioredoxin reductase activity in sheep serum was markedly higher in the Se0.5 group (p<0.05) and glutathione peroxidase activity in sheep liver was significantly higher in the Se1.0 group (p<0.01), and both began to decline afterwards. Dietary Se at >0.25 mg/kg significantly enhanced muscle thioredoxin reductase activity (p<0.05) and decreased the content of thiobarbituric acid reactive substances in the liver and muscle tissues (p<0.01). Different supplementary levels of SeY had no significant effect on pH values at 45 min and 24 h postmortem (p>0.05). Moreover, final dietary Se at >0.25 mg/kg was associated with significant decreases in the lightness and yellowness values of muscle tissues at 45 min (p<0.01), but had no obvious effect on the redness value (p>0.05). Meat color of mutton had a less change over time in the Se0.5 group, and the color stability was better. Drip loss of muscle decreased significantly with an increase in dietary SeY supplementation (p<0.05). In general, dietary supplemented with SeY to a final Se concentration of 0.5–1.0 mg/kg can maintain antioxidant capacity at a high level and obtain better meat quality of Tan sheep. The results of this study pave the way for the rational application of Se in the feed of Tan sheep.