Table 6. Treatment effects on protein carbonyl (PC, nmol/mg protein), malondialdehyde (MDA, nmol/mg protein), anti-superoxide anion (ASA, U/g protein), anti-hydroxyl radical (a-HR, U/mg protein), copper/zinc superoxide dismutase (Cu/Zn-SOD, U/mg protein), glutathione peroxidase (GPx, U/mg protein), catalase (CAT, U/mg protein) activities and glutathione (GSH, mg/g protein) content in grass carp muscle.
| Dietary isoleucine levels (g/kg diet) | ||||||
| 3.8 | 6.6 | 9.3 | 12.5 | 15.2 | 18.5 | |
| PC | 8.27±0.83d | 4.40±0.52b | 2.26±0.25a | 4.47±0.50b | 4.95±0.66bc | 5.18±0.38c |
| MDA | 1.54±0.12d | 0.92±0.09c | 0.60±0.06b | 0.61±0.04b | 0.36±0.04a | 1.63±0.16d |
| ASA | 29.71±1.99c | 33.91±3.79d | 30.42±1.27c | 25.75±1.59b | 18.95±0.63a | 19.65±1.08a |
| a-HR | 419.8±28.9c | 415.0±21.5c | 446.4±11.1d | 381.7±11.6b | 292.9±8.0a | 297.5±29.3a |
| Cu/Zn-SOD | 4.24±0.30b | 5.43±0.53c | 5.65±0.41c | 4.12±0.37b | 3.58±0.31a | 3.31±0.20a |
| GPx | 99.5±4.8a | 113.5±8.6b | 135.1±9.9c | 119.4±10.2b | 102.7±9.6a | 97.9±7.3a |
| CAT | 1.76±0.16d | 1.37±0.13c | 1.13±0.10b | 0.97±0.07a | 1.11±0.10b | 1.19±0.08b |
| GSH | 3.02±0.21a | 5.99±0.56c | 7.36±0.61d | 7.94±0.65e | 6.06±0.51c | 4.49±0.17b |
| Regression | ||||||
| YPC = 0.063×2−1.498x+12.264 | R2 = 0.667 | P = 0.192 | ||||
| YMDA = 0.021×2−0.469x+3.087 | R2 = 0.859 | P = 0.053 | ||||
| YASA = −0.053×2+0.194x+31.923 | R2 = 0.815 | P = 0.080 | ||||
| Ya-HR = −0.784×2+7.220x+410.426 | R2 = 0.810 | P = 0.083 | ||||
| YCu/Zn-SOD = −0.020×2+0.325x+3.710 | R2 = 0.683 | P = 0.178 | ||||
| YGPx = −0.493×2+10.376x+69.181 | R2 = 0.709 | P = 0.157 | ||||
| YCAT = 0.008×2−0.217x+2.457 | R2 = 0.976 | P<0.01 | ||||
| YGSH = −0.074×2+1.711x−2.261 | R2 = 0.958 | P<0.01 | ||||
Values are means ± SD (n = 6), and mean values within the same row with different superscripts are significantly different (P<0.05).