Table 6. Non-specific immune parameters and antioxidant enzyme activities of Pacific white shrimp Penaeus vannamei fed the experimental diets for 8 weeks

	PO¹⁾	NBT²⁾	Lysozyme³⁾	Antiprotease⁴⁾	SOD⁵⁾	GPx⁶⁾
Con	0.13 ± 0.01^c	2.61 ± 0.26^b	2.70 ± 0.23^b	46.0 ± 0.47^c	51.1 ± 1.53^b	27.3 ± 3.04^b
TB5	0.14 ± 0.01^bc	3.02 ± 0.13^a	3.18 ± 0.45^b	48.9 ± 0.72^bc	68.8 ± 1.26^a	29.7 ± 4.05^b
TB10	0.16 ± 0.01^ab	3.12 ± 0.03^a	4.53 ± 0.59^a	51.6 ± 1.49^ab	69.4 ± 2.32^a	41.0 ± 2.94^a
TB20	0.17 ± 0.01^a	3.09 ± 0.04^a	4.70 ± 0.99^a	54.3 ± 2.16^a	69.5 ± 0.85^a	45.9 ± 1.84^a
Pr > F*
ANOVA	0.001	0.001	0.002	0.000	0.000	0.000
Linear	0.000	0.001	0.000	0.000	0.000	0.000
Quadratic	0.892	0.011	0.632	0.893	0.000	0.412

Values are mean of four replicate groups (n = 4) and presented as mean ± SD.
Values with different superscripts in the same column are significantly different (p < 0.05).
Phenoloxidase activity (absorbance).
Nitro blue tetrazolium activity (absorbance).
Lysozyme activity (μg/mL).
Antiprotease (% inhibition).
Superoxide dismutase (% inhibition).
Glutathione peroxidase (mU/mL).
Con, basal diet; TB, tributyrin; TB5, TB10 and TB20 are 0.05%, 0.1% and 0.2% TB supplemented diets; ANOVA, analysis of variance.
Probability value associated with the F-statistic. Values < 0.05 indicate significant differences among treatments.