Partial substitution of frozen-fresh food by an experimental diet in Litopenaeus vannamei (Boone, 1931) (Decapoda: Dendrobranchiata: Penaeidae) broodstock.

The aim of this study was to determine the effect of completely or partially replacing fresh foods from the broodstock diet with an experimental diet. During a 40-day period, three dietary treatments were tested on Litopeaneus vannamei broodstock. As part of the first dietary treatment, denoted as "FF", broodstock shrimp were fed only fresh frozen food (squid, polychaete, mussel and Artemia biomass). The second treatment denoted as "ED" was 100% an artificial experimental diet. The third treatment, denoted as MD, comprised both the experimental diet and the fresh-frozen food (only squid and mussel were used). In terms of fertile spawns, females with ≥ 1 spawn, females with ≥ 2 spawn, and fecundity, the MD treatment did not differ significantly from the FF treatment. Fecundity was lowest among females receiving the ED treatment. MD treatment demonstrated equivalent fertility in females, and sperm rate in males to that of the FF treatment. The highest normal sperm rate was found in the ED and MD treatments. As a result, a combination of fresh food and the experimental diet resulted in a more balanced reproduction performance.

Immune gene expression and antioxidant response to vitamin E enriched diets for males Litopenaeus vannamei breeder (Boone, 1931).

The is aim of this study was to evaluate if vitamin E supplementation to diet could improve the spermatic quantity and quality in males of Litopenaeus vannamei. A basal diet with 171.5 mg/kg (included in commercial vitamin premix) and experimental diets with 3 concentrations of vitamin E: 620 (diet A), 1069 (diet B) and 1517 (diet C) mg/kg were tested by 30 days. 500 L tanks were set up for each treatment, and seven males were set in each tank. Circulant cholesterol, triglyceride (TG), glucose, total protein was measured. Sperm quantity and quality were classified as normal, abnormal, or dead. In reproductive tract was measured the activity and differential expression lipid soluble antioxidant system (LSAS) and of immune genes system. The higher sperm quantity was obtained in A diet and decreased in shrimp fed B and C diets (p < 0.05). Males fed diets B and C presented a higher activity and relative expression of lipid system oy suggesting oxidative stress. A significant increment of prophenol oxidase (proFo) and α-2-macroglobulin (α-2 M) transcripts were observed in males fed C diet (p < 0.05). All these variables were present in males with low sperm amount and low hemocyanin gene expression (p < 0.05). Therefore, diet A supplemented with 620 mg/kg vitamin E could benefit males L. vannamei broodstock, taking a count the sperm quantity and all the lipid and immune genes response.

Effects of using the biofloc system and eyestalk ablation on reproductive performance and egg quality of Litopenaeus vannamei (Boone, 1931) (Decapoda: Dendrobranchiata: Penaeidae).

The aim of this study was to evaluate egg production and quality of females of the Pacific white shrimp, Litopenaeus vannamei, in which there was or was not unilateral eyestalk ablation after there was pre-maturation culturing in biofloc or clear-water systems. Acylglycerides, cholesterol, glucose and total soluble protein were determined for the hepatopancreas, ovaries, hemolymph and eggs. Females cultured using the biofloc system had a larger number of eggs released per spawning and per gram of spawning specimen body weight. The number of total spawning's per week was comparable among treatments. Females cultured in the biofloc system in which there was no eyestalk ablation had that greatest concentrations of nutrient reserves in the hepatopancreas (P < 0.05) with the females cultured in the biofloc and clear-water system that had eye stalk ablation having the next most abundant nutrient reserves. There were the least concentrations of nutrient reserves in females with eyestalk ablation cultured in the clear-water system (P < 0.05). There, however, were no difference in nutrient reserve concentrations in the hemolymph and ovaries. In the eggs, there was the same trend among treatments as the hepatopancreas nutrient reserves, indicating that both eyestalk ablation and pre-maturation culture conditions (i.e., either biofloc or clear-water) affected the quality of eggs in L. vannamei.

A vibriosis outbreak in the Pacific white shrimp, Litopenaeus vannamei reared in biofloc and clear seawater.

In May and June 2015, moderate and severe lesions were observed in Litopenaeus vannamei reared in clear seawater while, at the same time, lesions in shrimp reared in biofloc were considerably fewer. The signs of disease included anorexia, lethargy, melanization, expanded chromatophores, luminescence and necrotic areas in the uropods, suggesting a possible vibriosis. However, lesions observed in shrimp reared in biofloc disappeared after a certain time and without mortality in tanks, whereas mortality and severe signs continued to be observed in shrimp reared in clear seawater. To treat the possible vibriosis, oxytetracycline was administered only in clear seawater tanks, but the results were not successful. Bacterial cultures from hepatopancreas tissues of shrimp from both rearing systems confirmed a vibriosis outbreak only in the clear seawater system. Subsequently, Vibrio harveyi, Vibrio rotiferianus, Photobacterium sp. and Photobacterium damselae were identified from bacterial culture previously isolated for both rearing systems by molecular methods. Shewanella sp. was isolated and identified only in biofloc. To understand the possible pathogenicity and resistance mechanisms of the Vibiro strains for both rearing systems, pathogenicity (toxR) and oxytetracycline resistance-related genes (tet(B), tet(D), tet(G)) were determined. Although these genes were expressed for both rearing systems, biofloc proved to have the ability to control the development of the disease, in comparison to clear water, where the vibriosis was evident regardless of the administration of oxytetracycline as a treatment.

The effect of copper on the color of shrimps: redder is not always healthier.

The objective of this research is to test the effects of copper on the color of pacific white shrimp (Litopenaeus vannamei) in vivo. Forty-eight shrimps (L. vannamei) were exposed to a low concentration of copper (1 mg/L; experimental treatment) and forty-eight shrimps were used as controls (no copper added to the water). As a result of this experiment, it was found that shrimps with more copper are significantly redder than those designated as controls (hue (500-700 nm): P=0.0015; red chroma (625-700 nm): P<0.0001). These results indicate that redder color may result from exposure to copper and challenge the commonly held view that highly pigmented shrimps are healthier than pale shrimps.

Nutritive value of diets containing fish silage for juvenile Litopenaeus vannamei (Bonne, 1931).

BACKGROUND: Fish wastes has been used for many years as an alternative in feeds for aquaculture. In the present study weight gain of juvenile white shrimp Litopenaeus vannamei fed diets including fish waste silage (WS), fish waste silage with soybean meal SBM (WS + S) or fish waste meal (WM) was compared. A conventional acidic silage process was applied to obtain from wastes (skin, heads, bones and viscera) of snapper (Lutjanus spp.), grunt (Haemulon plumieri), and grouper (Epinephelus spp.) an ingredient rich in protein. RESULTS: After 3 days ensilage more than 90% protein was hydrolysed. Waste material processed at pH 3.8 lost about 24% tryptophan. Butylated hydroxytoluene (BHT) prevented lipid oxidation, as shown after 45 days with malonaldehyde production. Shrimp fed WS + S diet gained 0.7 g per week higher than those fed WS and WM diets with 0.3 g per week (P < 0.05). CONCLUSION: WS processed with formic acid under conditions of low pH is beneficial for the white shrimp L. vannamei. It sustained reasonable weight gain combined with soybean meal in practical diets. On the other hand, BHT addition was beneficial in preventing oxidative action during silage preparation.

Relation between reproductive, physiological, and immunological condition of Litopenaeus setiferus pre-adult males fed different dietary protein levels (Crustacea; Penaeidae).

The present study was designed to evaluate the effect of amount of dietary protein levels on blood indicators of protein metabolism and immune condition (blood protein, hemocyanin, osmotic pressure, and hemocytes concentrations), and reproductive capacity of pre-adult Litopenaeus setiferus males (F0). Assessments were made of the relationship between amount of dietary protein, immune condition, and reproductive condition of the shrimp during the maturation process. Three different diets, with different amounts of protein (DP; 35, 45, and 55%), were evaluated over 55 days and compared with shrimp that were from a baseline group before treatments were administrated. Osmotic pressure, hemocyanin, blood protein, and hemocytes were greater in shrimp from control ponds than those obtained of shrimp fed 35 and 45% DP and similar to that obtained in shrimp fed 55% DP, demonstrating that food in the control pond had a nutritional value to that obtained by feeding amounts of dietary protein beyond 45%. Osmotic pressure, hemocyanin (Hc), blood protein (BP), and hemocytes were influenced by amount of DP with the physiology and immune system of shrimp being influenced by diet. At the same time, a maximum reproductive condition (measured as a proportion of normal cells of the total sperm cells) of shrimp males was observed in shrimp fed 45% DPL with lesser normal cells being present in shrimp fed 35 and 55% DPL. These results indicate that an immune reaction can occur in response to dietary protein with excess DP affecting several physiological functions included the sperm synthesis and sperm quality. Influence on hemocytes concentration in shrimp fed protein in excess could activate an attack on sperm cells in the vas deferens provoking lose of sperm quality in such conditions. Results indicate an optimal DP of 45 for maintaining the broodstock bank of L. setiferus.

Factorial effects of salinity, dietary carbohydrate and moult cycle on digestive carbohydrases and hexokinases in Litopenaeus vannamei (Boone, 1931).

Litopenaeus vannamei were reared in close cycle over seven generations and tested for their capacity to digest starch and to metabolise glucose at different stages of the moulting cycle. After acclimation with 42.3% of carbohydrates (HCBH) or 2.3% carbohydrates (LCBH) diets and at high salinity (40 g kg(-1)) or low salinity (15 g kg(-1)), shrimp were sampled and hepatopancreas (HP) were stored. Total soluble protein in HP was affected by the interaction between salinity and moult stages (p<0.05). Specific activity of alpha-amylase ranged from 44 to 241 U mg protein(-1) and a significant interaction between salinity and moult stages was observed (p<0.05), resulting in highest values at stage C for low salinity (mean value 196.4 U mg protein(-1)), and at D0 in high salinity (mean value 175.7 U mg protein(-1)). Specific activity of alpha-glucosidase ranged between 0.09 and 0.63 U mg protein(-1), an interaction between dietary CBH and salinity was observed for the alpha-glucosidase (p<0.05) and highest mean value was found in low salinity-LCBH diet treatment (0.329 U mg protein(-1)). Hexokinase specific activity (range 9-113 mU mg protein(-1)) showed no significant differences when measured at 5 mM glucose (p>0.05). Total hexokinase specific activity (range 17-215 mU mg protein(-1)) showed a significant interaction between dietary CBH and salinity (p<0.05) with highest value (mean value 78.5 mU mg protein(-1)) found in HCBH-high salinity treatment, whereas in the other treatments the activity was not significantly different (mean value 35.93 mU mg protein(-1)). A synergistic effect of dietary CBH, salinity and moult stages over hexokinase IV-like specific activity was also observed (p<0.05). As result of this interaction, the highest value (135.5+/-81 mU mg protein(-1)) was observed in HCBH, high salinity at D0 moult stage. Digestive enzymes activity is enhanced in the presence of high starch diet (HCBH) and hexokinase can be induced at certain moulting stages under the influence of blood glucose level. Perspectives are opened to add more carbohydrates in a growing diet, exemplifying the potential approach for less-polluting feed.