Effects of ammonia on growth and molting of Litopenaeus vannamei postlarvae reared under two salinity levels

ABSTRACT

Litopenaeus vannamei postlarvae were exposed to 0, 6, 13, and 19 mg/L total ammonia nitrogen (TAN) treatments. After 45 days, shrimp weight and length were lowest under TAN concentrations of 13 and 19 mg/L (P ≤ 0.05). Maximum weight gain was observed in control and 6 mg/L treatments. Mortality was highest (80.55 ± 4.80%) under 19 mg/L reared in 35 ppt salinity. Average intermolt periods of PLs exposed to 0, 6, 13, and 19 mg/L TAN were 11.5 ± 0.7, 10.8 ± 1.3, 9.4 ± 1.0, and 8.7 ± 0.6 days under 35 ppt and 11.1 ± 0.5, 10.7 ± 0.6, 10.1 ± 0.5, and 9.5 ± 0.2 days under 45 ppt salinity. Although TAN increased postlarvae molting frequency, its negative effects on the shrimp growth and survival of PLs was directly linked to its concentration and exposure duration. Higher salinity reduces the effects of ammonia and increases the survival.     

Effects of the addition of Calanopia elliptica,Artemia franciscana,and Brachionus rotundiformis in a nursery biofloc system on water quality,growth, gut morphology,health indices,and transcriptional response of immune and antioxidant-related genes in Penaeus vannamei

Aquaculture International - A 56-day study was carried out to examine the addition of live foods a biofloc technology (BFT) system on Penaeus vannamei postlarvae performance (PL25, initial weight:...     

Dietary simultaneous replacement of fish meal and fish oil with blends of plant proteins and vegetable oils in yellowfin seabream (Acanthopagrus latus) fry: Growth,digestive enzymes,antioxidant status and skin mucosal immunity

A 56‐day nutritional research was performed to examine the influence of alternative vegetal protein and lipid sources on performance of yellowfin seabream fry (Acanthopagrus latus) (0.5 ± 0.0 g). In this regard, five isoproteic (Ca. 500 g/kg) and isolipidic (Ca. 150 g/kg) diets were formulated in which fish meal (FM) and fish oil (FO) were simultaneously replaced with blends of plant proteins (PP, soybean meal and corn gluten) and vegetal oils (VO, canola and soybean oils) at 20% (SR20), 40% (SR40), 60% (SR40) and 80% (SR80) levels, respectively; meanwhile, a control diet (SR0) was formulated based on FM and FO. Growth and feed utilization were not influenced by experimental diets. The fatty acid profile of fillet drastically altered by dietary treatments. Fish fed with the SR60 and SR80 feeds had higher total protease, trypsin and α‐amylase activities than other treatments. The antioxidant enzyme activities and glutathione content in liver were enhanced in fish fed with the SR40, SR60 and SR80 diets. Skin mucosal immune parameters including total protein content, alkaline phosphatase and alternative complement pathway activities in the control group were relatively lower than the vegetal treatments. According to these results, it is recommended that 410 g/kg of FM and 45 g of FO/kg can be replaced with alternative vegetal sources in diet for A. latus fry.     

Effects of different carbon sources and dietary protein levels in a biofloc system on growth performance,immune response against white spot syndrome virus infection and cathepsin L gene expression of Litopenaeus vannamei

A 5‐week study was performed to evaluate the effect of spoilage date extract (SDE) as the biofloc carbon source on Litopenaeus vannamei (5.4 ± 0.3 g) performance. The two levels of dietary protein (15% and 25% crude protein) and two carbohydrate sources (molasses‐M and SDE‐P) were tested including: M15, M25, P15 and P25. The minimum (0.2 ± 0.0 mg/L) and the maximum (0.5 ± 0.0 mg/L) of total ammonia nitrogen were observed in the P15 and M25 groups respectively. The highest protein efficiency ratio (6.1 ± 0.3) and protein productive value (112.3 ± 5.8%) were found in the P15 group (p < 0.05). No significant difference was found between biofloc treatments in the expression of cathepsin L gene in hepatopancreas (p > 0.05). The number of total haemocyte count (THC), semigranular cells (SGC) and granular cells (GC) of shrimp in SDE‐based biofloc treatments was relatively higher than those in molasses‐based biofloc treatments. Following the white spot syndrome virus (WSSV) challenge, a significant decrease in THC, SGC, GC and hyaline cell values was observed in all treatments (p = 0.001). Plasma biochemical parameters were significantly influenced by dietary protein levels, biofloc carbon sources as well as WSSV challenge test. In conclusion, SDE successfully could be used as an alternative carbon source for establishing a biofloc system in L. vannamei production.     

Effect of short‐term fasting and re‐feeding on growth,digestive enzyme activities and antioxidant defence in yellowfin seabream,Acanthopagrus latus (Houttuyn, 1782)

An 80‐day feeding trial was conducted to evaluate the influence of different short‐term fasting and re‐feeding strategies on growth and physiological responses in yellowfin seabream, Acanthopagrus latus (2.4 ± 0.2 g) fingerlings. The fish were subjected to four different feeding regimes, and the control group fed four times daily to apparent satiation throughout the whole feeding period, while the other three groups were deprived for 2, 4 and 8 days followed by 8, 16 or 32 days of re‐feeding (F₂R₈, F₄R₁₆ and F₈R₃₂, respectively) in repeated cycles for 80 days. The fish in the control and F₂R₈ groups had the highest and the lowest total length, respectively (p < .05). Moreover, fish exposed to F₄R₁₆ had the highest hepatosomatic indices, while control fish had the lowest hepatosomatic indices (p < .05). Fish in the F₂R₈ group relatively had higher catalase and glutathione‐S‐transferase activities than other groups (p < .05). Furthermore, total protease, α‐amylase and alkaline phosphatase activities in the F₄R₁₆ and F₈R₃₂ were higher than the F₂R₄ and control groups (p < .05). Overall, this study showed that compensatory growth in weight and length and digestive enzyme activities were observed in the F₄R₁₆ and F₈R₃₂; however, the increase in the activity of antioxidant enzymes in the F₈R₃₂ group indicated that oxidative stress remained after 80 days of re‐feeding in the liver.     

Production of biofertilizers using baker's yeast effluent and their application to wheat and barley grown in north Sinai deserts

Abstract

Effluent from the baker's yeast industry was experimented on as a culture medium for the growth and biomass production of diazotrophs. The effluent supported good growth of Azotobacter chroococcum, Enterobacter agglomerans and Klebsiella pneuomoniae, Azospirillum brasilense, Bacillus polymyxa and Pseudomonas putida and strongly proposed for biofertilizers production of associative diazotrophs. Slurry preparations containing natural polymers, e.g. Arabic gum (5%), pero-dextrin (20%), starch granules (10%) or gelatine (20%) were impregnated with cells of tested diazotrophs. With storage, entrapped cells of B. polymyxa were viable up to 160 days, while gradual decreases in Azospirillum numbers were recorded. Pero-dextrin, a by-product of the starch industry, was selected as the appropriate biocarrier accommodating diazotroph cells and maintaining prolonged survival rates and nitrogenase activity. Cell cultures of A. brasilense, A. chroococcum, B. polymyxa, E. agglomerans and P. putida were equally mixed and entrapped into pero-dextrin slurry biofertilizer formulation named as “BIOGRAMINA”. Tested diazotrophs successfully survived (ca. 10⁸ cfu ml^?1) in such formulation up to 6 months at both ambient and cold temperatures. The response of wheat and barley to “BIOGRAMINA” in the presence or absence of N fertilizers was evaluated in greenhouse and field trials. Highest total biological yields were recorded for inoculated plants simultaneously supplemented with rational N fertilizer dose.     

Enriched Artemia with L-lysine and DL-methionine on growth performance,stress resistance,and fatty acid profile of Litopenaeus vannamei postlarvae

A 15-day study was conducted to evaluate the effect of enrichment of Artemia metanauplii with four different emulsions, including: (A) Easy-DHA Selco; (B) Easy-DHA Selco + L-lysine (4 g/L); (C) Easy-DHA Selco + DL-methionine (4 g/L); and (D) Easy-DHA Selco + L-lysine (2 g/L) + DL-methionine (2 g/L) on growth and stress resistance of white leg shrimp Litopenaeus vannamei larvae (from Mysis I to postlarvae12). It is noticed that shrimp PL in group B had the highest wet (36.1 ± 3.1 mg) and dry (1116.7 ± 60.0 µg) weights as well as stress resistance to fresh water (64.0 ± 5.5%).