Antioxidant defence system based oxidative stress mitigation through dietary jamun tree leaf in experimentally infected snubnose pompano, Trachinotus blochii

Dietary Syzygium cumini leaf extract influences growth performance, immunological responses and gene expression in pathogen-challenged Cyprinus carpio

This study evaluated the effects of jamun leaf extract (JLE) as a feed supplement on growth performance, haemato-immunological, oxidative stress-related parameters, and cytokine gene expression in Cyprinus carpio challenged with Aeromonas hydrophila.. Diets containing four different JLE concentrations, that is, 0 (basal diet), 5 (JLE5), 10 (JLE10), and 15 g kg^-1 (JLE15), were fed to carp (6.27 ± 0.43 g) for eight weeks. Growth performance was significantly higher in JLE10. Haemato-immunological and antioxidant parameters were determined in fish at 48 h post-challenge with A. hydrohila. The cumulative survival was highest in JLE10 (69.69%) 14 days post-challenge. Serum protein (2.18 ± 0.06 g dL^-1), lysozyme (32.38 ± 1.2 U mL^-1), alternative complement pathway (70.43 ± 1.61 U mL^-1), phagocytic activity (21.18 ± 0.48%), respiratory burst activity (0.289 ± 0.09 OD_630nm), and immunoglobulin levels (6.67 ± 0.36 U mg mL^-1) were significantly higher in JLE10 than in the control. Serum alanine aminotransferase (44.06 ± 1.62 Unit mL^-1), aspartate aminotransferase (31.58 ± 1.82 Unit mL^-1), and malondialdehyde (2.57 ± 0.26 nmol mL^-1) levels were lower in JLE10 than in the control (p < 0.05), whereas myeloperoxidase activity was significantly higher in JLE5 and JLE10 than in the control. Superoxide dismutase levels in the serum were higher (p < 0.05) in JLE5 and JLE10 than in the other groups. Gene expression analysis revealed that the mRNA expression of pro-inflammatory cytokines TNF-α and IL-1β was upregulated (p < 0.05) in the liver, head-kidney, and intestine of challenged carp in JLE10. The signalling molecule NF-κB p65 was upregulated in lymphoid organs in JLE10 but not in the liver. The anti-inflammatory cytokine IL-10 was significantly downregulated in challenged carp in JLE10 compared with that in the control. Quadratic regression analysis showed that optimal dietary JLE was estimated to be 9.03-10.15 g kg^-1 to maximize the growth performance. Results of the present study revealed that dietary JLE at 10 g kg^-1 can significantly improve the immunity and disease resistance of C. carpio. Thus, JLE is a promising food additive for carp aquaculture.

Enzymological, histological, and serum biomarker responses of snubnose pompano on complete replacement of fishmeal using cottonseed meal supplemented with lysine and methionine in the diet

In a feeding experiment, cottonseed meal (CSM) was used to replace fishmeal (FM) in the diet of snubnose pompano, Trachinotus blochii, supplemented with lysine and methionine to assess the growth, nutritive profile, hematological, histological, and stress biomarker response. Experimental fishes were randomly stocked in five treatments each with triplicates. Five isonitrogenous and isolipidic diets with graded level of CSM (0, 8.7, 17.4, 26.0, and 34.7%) as replacement for FM protein (0, 25, 50, 75, and 100%) were formulated and fed to respective treatments. Comparison between various parameters among the treatments was made using orthogonal polynomial contrasts to indicate the statistical significance. Higher alkaline phosphatase, acid phosphatase, lactate dehydrogenase, malate dehydrogenase, aspartate, and alanine aminotransferase activities were observed in 0CSM group and followed by 100CSM group as higher inclusion level of CSM with higher free gossypol content did not affect the metabolic enzyme activities. The maximum muscular free gossypol accretion of 1.28 mg kg^-1 (on wet basis) was recorded in 100CSM group which was very well below the critical limit set by FDA. As a conclusion, fishmeal can be completely replaced using cottonseed meal in the diet of pompano without adverse effect on growth, metabolism, and general health.