Hyperthermal stress potentiates enhanced lipid utilisation in genetically improved farmed Tilapia, Oreochromis niloticus juveniles.

The present experiment evaluated whether dietary protein (P) or lipid (L) is preferred as an energy source by genetically improved farmed tilapia (GIFT) reared at high temperatures. A 60-day feeding trial was conducted at 28.3 °C and 33.3 °C, testing five diets with varying protein (34,36,38 %) and lipid (8,10,12 %) levels, viz., P38L8, P36L8, P34L8, P34L10, P34L12. Parameters assessed included growth, body composition, serum lipids, enzyme activities, fatty acid profiles, and PPAR-α mRNA expression. Results indicated that the fish fed optimum protein and highest lipid level (P34L12) showed significantly higher (P < 0.05) weight gain percent and thermal growth coefficient. Increasing dietary lipid content reduced whole-body lipid deposition and mobilised serum triglycerides and cholesterol at higher temperatures (HT). Hepatic malic enzyme activity decreased with rising temperature and lipid content, while lipoprotein lipase activity in muscle increased. The fatty acid composition altered substantially with the changes in rearing temperature and diets. Unsaturated fats were preferred as direct fuels for ß-oxidation, wherein the P34L12 groups preserved body (area %) EPA, DHA, and linolenic acid, especially at HT. The expression of PPAR-α, a lipolytic marker, was upregulated with increasing temperature and high dietary lipid content, peaking in P34L12 groups. The study concludes that high-lipid diets (12 %) are metabolically superior to high-protein diets for GIFT tilapia at elevated temperatures, optimising growth, enhancing metabolic efficiency, and maintaining essential fatty acid profiles under hyperthermal stress.

Antiparasitic potentiality of ethanol and methanol extracts of Azadirachta indica leaf for eggs and copepodid stage of Argulus japonicus: in vitro study.

In the present study, eggs and copepodid stages of Argulus japonicus were treated with ethanol and methanol extract of Azadirachta indica (neem) leaf and its antiparasitic efficacy (AE %) was determined. The experiments were performed in triplicate along with the positive (2% DMSO) and negative (without DMSO and extract) control groups. The reduced cumulative hatching percentage of eggs by 13% (in ethanolic) and 17% (in methanolic) extract of neem leaf at 1.5 g L-1 was obtained during 15-day exposure compared to the control group showing 70-85% eggs hatching. The AE of 100% for ethanolic and 91.66% for methanolic extract against the copepodid stage was found at 1.25 and 1.5 g L-1 respectively in 6 h. The histological analysis of the eggs showed the undifferentiated decaying mass of cells with extensively damaged eggs when treated with ethanolic extract of neem leaf. Further, severe degeneration in the branchial region, digestive tract and eye cells was observed in the copepodids treated with ethanol extract than the methanol extract. The terpenoids a potential antiparasitic compound of ethanolic extract produced more AE than the methanolic extract. Thus, the ethanolic extract of neem leaf can be potentially utilized as a natural parasiticide to disrupt the egg and other life phases of A. japonicus.

Physio-metabolic and haematological changes of Labeo rohita fed with graded level of de-oiled rice bran-based diet.

A 60-day feeding trial was conducted with six experimental diets containing 260 g/kg crude protein and 70 g/kg lipid with varying level of de-oiled rice bran (DORB), viz., 33 (T33), 38 (T38), 43 (T43), 48 (T48), 53 (T53) and 58% (T58) to assess the digestive, metabolic and haematological responses in Labeo rohita. One hundred and eighty (180) fingerlings with ten fish per tank having an average weight of 9.8 ± 0.5 g were randomly distributed within six treatments in triplicates following a completely randomised design. The amylase and lipase activities in the whole intestine did not vary significantly (P > 0.05), but protease activity varied significantly with respect to DORB level in the diet. At higher (53 and 58%) inclusion level of DORB, the protease activities were lower. T33, T38 and T43 groups showed significantly (P < 0.05) higher aspartate aminotransferase (AST) activity compared to the other groups, whereas lowest activity was recorded in the group fed with highest inclusion level (58%). The oxidative stress enzyme like superoxide dismutase (SOD), catalase and glutathione-S-transferase exhibited significantly higher activities in liver of T58 group of L. rohita. However, the activity of catalase and SOD showed no significant variation in gill tissue. The haematological parameter values such as red blood cell (RBC), white blood cell (WBC), haemoglobin (Hb) and packed cell volume (PCV) were lower in the highest DORB fed group (T58) as compared to their lower DORB inclusion counterparts. No change in NBT value was recorded irrespective of DORB inclusion level in the diet. Hence, from these results, it can be concluded that the dietary inclusion of DORB up to 43% in the diet of L. rohita at 26% crude protein and 7% lipid level is best for the optimal activity of digestive, metabolic and haematological parameters.

Effect of Withania somnifera (L. Dunal) root as a feed additive on immunological parameters and disease resistance to Aeromonas hydrophila in Labeo rohita (Hamilton) fingerlings.

The present study evaluated the efficacy of dietary doses of Withania somnifera (Ashwagandha) root powder on immunological parameters and disease resistance against the bacterial pathogen Aeromonas hydrophila infections in Indian major carp, Labeo rohita fingerlings. Fishes were fed with dry diet containing 0 gkg(-1) (control), 1 gkg(-1) (T(1)), 2 gkg(-1) (T(2)) and 3 gkg(-1) (T(3)) W. somnifera root powder for 42 days. Immunological (NBT level, Phagocytic activity, total immunoglobulin and lysozyme activity) parameters of fishes were examined at 0 days, 14 days, 28 days and 42 days of feeding. Fishes were challenged with A. hydrophila 42 days post feeding and mortalities (%) were recorded over 14 days post-infection. The results demonstrate that fishes fed with W. somnifera root showed enhanced NBT level, Phagocytic activity, total Immunoglobulin level and lysozyme activity (p<0.05) compared with the control group. The survivability was higher in experimental diets than the control group. Dietary W. somnifera at the level of 2 gkg(-1) showed significantly (P<0.05) higher protection (RPS 42.85+/-0.65%) against A. hydrophila infection than control. The results suggest that the W. somnifera root powder have a stimulatory effect on immunological parameters and increases disease resistance in L. rohita fingerlings against A. hydrophila infection.