No abstract

Alternative sources of fish oil (FO) are one of the major problems in aquaculture; therefore, the goal of the present study was to examine insect (black soldier fly larvae) oil (BSLO) as a potential replacer of fish/soy oil in juvenile rainbow trout (initial average weight of 32 ± 0.15 g) feed. Four diets were formulated wherein FO (control diet) was completely replaced with either soybean oil (SO) or BSLO, and an additional BSLO-based diet supplemented with 1.5% bile acid (BSLO + BA) were fed to the fish for 10 weeks. Growth performance of the BSLO fed group was similar ( P > 0.05) to that of the FO and SO fed groups, however, the fish fed BSLO + BA diet registered the lowest growth ( P < 0.05). Oil sources did not ( P > 0.05) affect the major nutrient content of whole-body, however, the fatty acid composition of the muscle and liver was influenced ( P < 0.05), with the highest 14:0, 16:0, and total saturated fatty acid detected in BSLO or BSLO + BA fed trout compared to the others ( P < 0.001). No significant differences were observed in eicosapentaenoic acid + docosahexaenoic acid (EPA + DHA) or total n-3 polyunsaturated fatty acid (PUFA) content in muscle among the groups, whereas, the highest EPA:DHA and n-3:n-6 ratios were detected in the FO group. Gene expression for fatty acid binding protein ( fabp ) , fatty acid synthase ( fas ), and Δ5 desaturase in the liver was lower in FO ( P < 0.05), while BSLO + BA registered the highest Δ6 expression ( P = 0.006). Supplementation of BA in the BSLO diet increased superoxide dismutase (SOD) and catalase (CAT) activities compared to the other groups ( P < 0.05). In conclusion, BSLO could serve as a substitute for FO and SO in rainbow trout diet without negatively impacting growth performance, whole-body composition and nutrient retention, and modulate the expression of fatty acid metabolism-related genes in rainbow trout.

No abstract

Aquaculture is a growing agribusiness, and large-scale microbial infection frequently leads to considerable economic losses, as there are very few approved drugs available to counteract such a problem. Aloe vera is a natural therapeutic plant with biological activities, for example, antimicrobial, anticancer, mitigating, and immunomodulatory properties. Thus, an experiment was conducted to understand the effects of dietary Aloe vera on survival, growth performance, protein utilization, gastrosomatic index, and gut histomorphological studies in common carp in laboratory conditions. Aloe vera leaves were collected, washed, shade-dried, and homogenized to get a filtrate, which was extracted in ethanol (70%) using the Soxhlet apparatus. The carp with an average weight of 1.73 ± 0.14 g was divided randomly into 5 treatments (control and other 4 treated groups) with the extract of 0.0%, 0.2%, 0.4%, 0.8%, and 1.6% in the diet with 3 replicates and the stocking density was 25 fish per each replicate. Sampling was done on the 30th, 60th, and 90th days, and the results show that percent weight gain, specific growth rate, protein efficiency ratio, and feed conversion efficiency were significantly high in the treated diet compared to the control (0.0%). Gastrosomatic index, condition factors, and gut histology found better performance in common carp group fed 0.4% and 0.8% of Aloe vera after 90 days. In conclusion, it was found that Aloe vera extract between the amount of 0.4% and 0.8% is better for fish growth for common carp.

This study investigates the effects of Lapsi Fruit Extracts (LFE) Choerospondias axillaris (Roxburg 1832) on growth performance, haematology, biochemical with some growth and immune-related genes in silver carp fingerlings (Hypophthalmichthys molitrix). For this purpose, three hundred and seventy-five fish (5.17±0.13g) divided into six groups into eighteen aquaria and fish were fed six purified diets supplemented with ethanol extract (80%) of lapsi fruits (LFE) as A (0.0 g control), B (0.2 g), C (0.4 g), D (0.8 g), E (1.6 g), and F (3.2 g /100 g) for 90 days. Significantly higher (P<0.05) weight gain, %weight gain, SGR, and lysozyme were recorded in D (0.8 g) diet-fed group, while FCR was higher in the control diet group. In haematology, no significant differences (P>0.05) were observed among the treated and control diet-fed group while reducing trends were observed in SOD, CAT, and GPx levels as compared to control. Glucose, triglyceride, and cholesterol level were higher in control and the decreasing trend observed in continuous feeding of the LFE supplemented diet. Protein albumin and globulin level were always higher (P<0.05) in all the treated groups and was better in D (0.8 g) diet-fed group. As compared to -actin gene, growth hormone (GH), insulin-like growth factors I and II (IGF-I and IGF-II) in the liver were always higher and similar results were observed in immune‐related genes interleukin‐8 (IL-8), interleukin-10 (IL-10) and tumor necrosis factor (TNF- ) in the head kidney of silver carp. The results suggest that lapsi fruit extracts (LFE) can be useful as a feed supplement for proper growth and enhance disease resistance by improving immunity in blood, liver, and head-kidney tissues.

An experiment was conducted at Corona of Agriculture (COA)”, Gunjanagar-3, Chitwan, Nepal to complete a project granted by University Grant Commission (UGC), Second Higher Education Project (SHEP) in 2013. Four (average 380 m2) ponds (W, X, Y and Z) with four different diets as D1 (20%), D2 (30%), D3 (40%) and D4 (50%) protein contents were used to conduct the experiment properly to determine the varied proportion of dietary protein on the growth performance of major carp rohu Labeo Rohita (H) in relation with RNA: DNA ratio. After 12th weeks of culture, average length, average weight and specific growth rate of fish were found significantly (P<0.05) higher in the carp with D3 and D4 diet fed fish. Similar results were observed in average total protein, albumin and globulin contents. RNA content increased rapidly with age. The average RNA content increased highest in D2 and D3 diet fed fish while, DNA content were highest in D3 diet fed fish.  RNA: DNA ratio was recorded highest in D2 and D3 diet fed fish. RNA: DNA ratio, an indicator of protein synthesis and have been used to accurately estimate the growth rate and feeding condition of fish hence, as the dose of protein increased RNA and DNA contents also increased with age of carp cultured during experiment. Thus, it was clear from this study that the incorporation of protein in diet enhances the growth of fish regardless of species weight groups and the doses, as the average weight of fish was significantly lower in control diet fed fish as compared to the treated one.

No abstract

The present outdoor experiment was carried out to evaluate the effect of dietary supplementation of lapsi Choerospondias axillaris (Roxburgh, 1832) on haematological parameters in rainbow trout Oncorhynchus mykiss in Nepal. The lapsi fruits were obtained from local market of Kathmandu. The feeding trail was conducted for 90 days. About 270 trout with similar body weight (5±1g) were distributed randomly at the rate of 15 fishes per cage (1m3) into 18 cages placed in raceway pond. Six practical diets containing 40% protein were prepared as T1 (0.0 g kg-1) T2 (0.1 g kg-1), T3 (0.2 g kg-1), T4 (0.4 g kg-1), T5 (0.8 g kg-1) and T6 (1.6 g kg-1) supplemented by the ethanol extract of lapsi fruits along with other usual ingredients viz. fish meal, wheat flour and cod liver oil etc. At the end of the experiment the haematological parameters were measured. A significant difference (P< 0.05) in haematological parameters was observed between the treated diets fed groups to that of control diet fed group. Total erythrocytes count (RBC), Haematocrit (Hct), Haemoglobin concentration (Hb), and erythrocyte indexes (MCV, MCH and MCHC) were found significantly higher in T4 (0.4 %) diet fed trout as compared to the control. A minimum of 0.4 % (0.4g kg-1) lapsi fruit extract in fish feeds gave more increase in haematological parameters of Oncorhynchus mykiss. Inclusion of lapsi fruit extract at 0.4 % concentration is therefore could be used effectively in aquaculture.