Synchronization of ovulation in cultured northern whitefish (Coregonus peled,Gmelin 1788) using [D‐Arg6Pro9Net]‐sGnRH analogue and its effect on egg quality

Female northern whitefish were treated with salmon [D‐Arg⁶Pro⁹Net]‐sGnRHa emulsified in Freund′s incomplete adjuvant as a sustained release treatment (sGnRHa‐FIA) or with [D‐Arg⁶Pro⁹Net]‐sGnRHa dissolved in physiological saline as acute release treatment (sGnRHa‐PS). Females in four experimental groups (A, B, C, D) and one control group (E) were injected intraperitoneally as follows: A and B – sGnRHa‐FIA at doses of 50 and 25 μg kg^?1, respectively; C – double injection (DI) of sGnRHa‐PS at 25 μg kg^?1 administered 3 days apart; D – single injection (SI) of sGnRHa‐PS at 25 μg kg^?1; and E – control group receiving a 1:1 mixture of FIA and physiological saline. All treatments induced and synchronized ovulation. Mean time to ovulation was significantly reduced (P < 0.05) in GnRHa‐treated groups compared with control. Hormone treatments did not affect the relative fecundity. Slight differences were found in ovarian fluid pH between group A and D (P < 0.05). Except for group C, egg size was significantly reduced (P < 0.01) in hormonally synchronized groups compared with the control. Survival to the eyed stage of eggs from females in groups A, B and C was significantly lower (P < 0.01) than in groups D and E. Per cent hatched alevins was lower (P < 0.01) in groups A, B and C than in groups D and E. We conclude that synchronization of ovulation in northern whitefish can be induced by a single acute injection of [D‐Arg⁶Pro⁹NEt]‐sGnRHa at 25 μg kg^?1 BW if given near the natural spawning time determined by water temperature below 2°C.     

Ovulation induction in jundiá (Rhamdia quelen,Heptapteridae) using carp pituitary extract or salmon GnRH analogue combined with dopamine receptor antagonists

Jundiá (Rhamdia quelen) is an important species for aquaculture in temperate and subtropical climates. In the present study, the results of different forms of GnRH analogue treatments on ovulation in jundiá have been compared with those from treatment with carp pituitary. Seven out of eight females ovulated in groups treated with carp pituitary (4.0 mg kg^?1 BW) and Ovaprim (0.5 mL kg^?1 BW). Injection with sGnRHa (10 μg kg^?1 BW) combined with metoclopramide (20 mg kg^?1 BW) caused a significantly lower rate of ovulation with three out of eight females responding. None of the fish injected with sGnRHa (10 μg kg^?1 BW) alone ovulated. Mean PGSI [(weight of stripped egg mass/BW of the female before stripping) × 100] and mean fertilization rate values were high and similar between treatment groups. The obtained results indicate that in jundiá, there is a strong dopamine inhibitory tone on gonadotropin secretion. The gonadotropin releasing activity of sGnRHa can be potentiated by dopamine receptor antagonists and the combined treatment is effective in inducing ovulation. In this regard, domperidone proved to be more potent than metoclopramide.     

Hormonal induction of ovulation in pikeperch (Sander lucioperca L.) using human chorionic gonadotropin (hCG) and mammalian GnRH analogue

The aim of the present study was to study spawning stimulation in artificial reproduction of females pikeperch (Sander lucioperca L.) using “Chorulon” containing the human chorionic gonadotropin (hCG) and compare with “Supergestran” containing a mammalian GnRH ([D-Ala⁶]GnRHProNhet) analogue. The females were divided into eleven experimental groups and injected with hCG at 250, 500, 750, and 1 000 IU kg^?1 body weight (BW) and mGnRHa at 1, 2.5, 5, 10, 25, and 50 μg kg^?1 BW. In all treatments, a single intramuscular injection of hormone was performed. Control group was injected with 0.9 % NaCl, 0.9 cm³ kg^?1 BW. The average percentages of ovulating females were 88.5 ± 12.3 and 80.8 ± 10.9 % in hCG- and mGnRHa-treated groups, respectively. The average diameter of eggs was 0.95 ± 0.06 and 0.98 ± 0.06 mm in hCG- and mGnRHa-treated groups, respectively. Neither ovulation rate nor diameter of egg was statistically differed among hormonally treated groups. Statistical difference was observed only in hatching rate, where the average were 73.6 ± 14.4 and 50.6 ± 17.7 % in hCG and mGnRHa-treated groups, respectively. Among hormonally treated groups, the best results were observed in groups treated with hCG at 500 and 750 IU kg^?1 and in groups treated with mGnRHa at 25 μg kg^?1. No ovulation was observed in the control group. This study indicated successful ovulation in pikeperch using a single intramuscular injection of hCG or mGnRHa analogue.     

The improvement of growth,digestive enzyme activity and disease resistance of white shrimp by the dietary citric acid

A 45-day feeding trial was conducted to evaluate the effects of dietary citric acid on growth, digestive enzyme and disease resistance of white shrimp, Litopenaeus vannamei. Shrimp with initial body weight of 5.57 ± 0.21 g were fed with basal diet supplemented with 0.0 g kg^?1 (control), 1.0, 2.0, 3.0, 4.0 and 5.0 g kg^?1 citric acid. Results showed that weight gain was increased by 15.9 % and feed conversion ratio was decreased by 0.17 by 2.0 g kg^?1 dietary citric acid compared with control group (P < 0.05). Intestinal protease activity of shrimp fed 2.0 g kg^?1 citric acid was significantly higher (P < 0.05) than that of control group. No significant difference was found in intestinal amylase activity among treatments (P > 0.05). The activities of serum phenoloxidase, superoxide dismutase and lysozyme in 2.0 and 3.0 g kg^?1 citric acid group were significantly higher, and accumulative mortalities of the two groups on the fourth day after injection of Vibrio alginolyticus were significantly lower than those of control group (P < 0.05). Results above demonstrated that dietary citric acid could improve growth performance, immunity and resistance against V. alginolyticus. The supplementation level of citric acid in diet was suggested to be 2.0–3.0 g kg^?1 for white shrimp.     

Effect of thiamine injection on growth performance,hematology and germinal vesicle migration in sterlet sturgeon Acipenser ruthenus L.

The present study aimed to investigate the effect of thiamine on growth, hematological, egg thiamine content and oocyte nucleus migration indices in sterlet sturgeon (Acipenser ruthenus). A total of 45 female fish (698.6 ± 8.9 g) were distributed in nine fiberglass tanks with three treatments (each in three replicates). Experimental fish were fed once a day with practical diet supplemented with 1 g kg^?1 amprolium hydrochloride (as the antithiamine) for 5 months before spawning. Thiamine hydrochloride was injected to fish with one of three doses at 0, 5 and 50 mg kg^?1 body weight (BW) at three different stages. At the end of each month, fish were weighed and growth parameters such as weight gain, specific growth rate, feed efficiency and final weight were determined. At the end of the 5-month period, hematological parameters and egg thiamine content were measured. The results showed no significant differences in terms of growth performance. Hemoglobin, number of red blood cells and white blood cells were not significantly different among the treatments, but hematocrit was significantly higher in fish injected with 5 mg kg^?1 BW thiamine. The mean corpuscular volume and mean corpuscular hemoglobin were not significantly different, but lower value of mean corpuscular hemoglobin concentration was observed in fish injected with 5 mg thiamine. Percentage of lymphocytes, neutrophils, eosinophils and monocytes were not significantly different among treatments. The results of the germinal vesicle migration index at different stages showed no significant differences in different groups. Results showed that free thiamine, thiamine pyrophosphate and total thiamine in eggs significantly increased at 50 mg kg^?1 injection dose compared with the control, but no significant different was found in thiamine monophosphate. The results revealed that thiamine injection to sterlet broodstocks has positive accumulation in egg thiamine content and some hematological parameters but have no effect on growth and ovarian maturation. We conclude that thiamine can affect some physiological features of broodstock, which needs to be specified in further studies.     

Effect of dietary mannan oligosaccharide (MOS) on growth performance, survival, body composition, and some hematological parameters in giant sturgeon juvenile (Huso huso Linnaeus, 1754)

The effect of dietary mannan oligosaccharide (MOS; activeMOS^®) on growth, survival, and body composition in giant sturgeon juvenile (Huso huso) with initially average weight 46.89 ± 2.57 was investigated for a period of 46 days. Basal diet were supplemented with 0 (control), 2, and 4 g kg^?1 MOS in a totally randomized design trial in triplicate groups. The results showed no significant differences in growth and feeding parameters between control and treatment groups (MOS supplementation diets) (P > 0.05). There was a statistically significant decrease (P < 0.05) in feed per fish level in only group treated with 4 g kg^?1 MOS. The highest and the lowest growth performances were observed in 2 and 4 g kg^?1 MOS, respectively. There were no significant differences in survival rate among all treatment groups (P > 0.05). In group treated with 2 g kg^?1 MOS was a significant difference in lipid carcass (P < 0.05), whereas protein, ash, and moisture remained unaffected (P > 0.05). However, no significant difference was observed in intestinal lactic acid bacteria between all treatment groups (P > 0.05). There were no significant differences in hematological parameters between control and MOS treatment groups (P > 0.05). These results suggested that the prebiotic mannan oligosaccharide did not influence the growth performance in giant sturgeon juvenile, and it is not appropriate for supplementation in the diet of cultured juvenile giant sturgeon.     

Effect of prebiotic konjac mannanoligosaccharide on growth performances,intestinal microflora,and digestive enzyme activities in yellow catfish,Pelteobagrus fulvidraco

In the present study, konjac mannanoligosaccharide (KMOS) was evaluated as a prebiotic in yellow catfish. The fish were fed with diets containing KMOS in four concentrations: 0 g kg^?1 (C), 1.0 g kg^?1 (KM1), 2.0 g kg^?1 (KM2), and 3.0 g kg^?1 (KM3) for 49 days, respectively. Another group fed with diets containing 3.0 g kg^?1 yeast cell wall mannanoligosaccharide (MOS) (M3) was set as positive control. The results indicated that fish receiving the diets supplemented with KMOS or MOS showed higher relative gain rate (RGR), specific growth rate (SGR), and lower feed conversion ratio (FCR) with significantly differences (P < 0.05) than those fed with the basal diets. Moreover, fish receiving the diets with 2.0 g kg^?1 KMOS inclusion showed higher RGR, SGR, and lower FCR (P < 0.05) than that feeding the diets supplemented with 3.0 g kg^?1 MOS. The quantities of Bifidobacterium spp. were significantly increased (P < 0.05). Meanwhile, Escherichia coli and Aeromonas spp. were significantly reduced (P < 0.05) in the fish-feeding diets with 2.0 g kg^?1 KMOS supplement. Compared with the control group, the significantly enhancement of protease and amylase activity (P < 0.05) in intestine and pancreas was observed in fish fed with diets containing KMOS or MOS. Collectively, an optimum level of KMOS inclusion in diets could modulate intestinal microflora, induce digestive enzyme activity, and improve the growth performance of yellow catfish significantly.     

Dietary protein and carbohydrate requirement of juvenile Hawaiian limpet (<Emphasis Type="Italic">Cellana sandwicensis</Emphasis> Pease, 1861) fed practical diet

This study was conducted to evaluate dietary protein and carbohydrate requirement of juvenile Hawaiian limpets Cellana sandwincensis. A total of 64 juvenile limpets (3.12 ± 0.86 g) were fed five different dietary protein levels ranging from 270 to 470 g kg^?1 for 90 days. Carbohydrate and lipid levels were held constant at 180 and 49.7 g kg^?1, respectively. Weight gain and growth rates of the animals did not differ significantly (P > 0.05) among the protein levels ranging from 270 g kg^?1 (0.30 % day^?1) to 470 g kg^?1 (0.23 % day^?1). Next, opihi were fed four diets with protein levels from 210 to 500 g kg^?1 with a constant carbohydrate level at 120 g kg^?1. Weight gain and specific growth rates of opihi increased with increasing dietary protein from 210 to 350 g kg^?1, and significantly (P < 0.05) decreased at the 500 g kg^?1 diet. Highest weight gain, growth rates, and protein efficiency ratio were achieved at 350 g kg^?1. Elevated carbohydrate levels (180–370 g kg^?1) produced a significant difference (P < 0.05) in growth. The fastest growth rates of animals were obtained with 270 g kg^?1 (0.27 % day^?1) and 320 g kg^?1 (0.26 % day^?1). The weight gain of animals fed 180 and 370 g kg^?1 carbohydrate diets were significantly (P < 0.05) lower than those of animals fed 270 and 320 g kg^?1. We conclude that about 350 g kg^?1 protein and 320 g kg^?1 carbohydrate levels could be used for opihi.     

Effects of practical dietary protein to lipid levels on growth,digestive enzyme activities and body composition of juvenile rice field eel (Monopterus albus)

A 10-week feeding experiment was conducted to evaluate the effects of dietary protein to lipid ratios (P/L) on growth, intestinal digestive enzyme activities and body composition in juvenile rice field eel (Monopterus albus) (initial mean body weight of 65.76 ± 1.07 g, mean ± SEM). Nine test diets were formulated in a 3 × 3 factorial design to contain three protein levels (350, 400 and 450 g kg^?1) for each of three lipid levels (40, 80 and 120 g kg^?1), respectively. Each diet was randomly assigned to triplicate groups of 60 fish per net cage (1.5 × 2.0 × 1.5 m). Results showed the survival was above 96 % and was not affected by dietary treatments. Fish fed the diet with 450 g kg^?1 protein and 40 g kg^?1 lipid showed the best weight gain (WG) (103.95 %) and feed conversion ratio (1.60) (P < 0.05). WG, protein efficiency ratio and energy retention increased with the increasing in lipid at 350 g kg^?1 protein level (P < 0.05). However, WG showed a little decline with increasing dietary lipid when fish fed the diets with 400 and 450 g kg^?1 protein level, but no significant difference was observed (P < 0.05). Hepatosomatic index, visceralsomatic index and intestinal lipase activity increased with the increasing of dietary lipid level irrespective protein level. Intestinal trypsin activity increased with the increasing of dietary lipid level when fish fed the diets with 350 g kg^?1 protein, but showed converse trend when fish fed the diets with 400 and 450 g kg^?1 protein. Serum triglyceride, body lipid and energy were positively correlated with the dietary lipid. Results of the present study showed that the dietary protein/lipid ratio of 450/40 g kg^?1 is considered optimum for rice field eel under culture conditions, and the increase in dietary lipid level has no efficient protein-sparing effect when fish fed the diets with 400 and 450 g kg^?1 protein level.     

Modulatory role of L-carnitine against microcystin-LR-induced immunotoxicity and oxidative stress in common carp

Microcystin-LR (MCLR), one of the most popular microcystins (MCs) found in many field water bodies around the world, poses great health risks to animals and humans. In the present study, healthy common carp (initial weight 24.8 ± 2.3 g) were randomly assigned to five groups. Group I was fed on normal diet as control. Group II was maintained on normal diet and received MCLR intraperitoneal injection (150 μg kg^?1 BW). Common carp in groups III, IV, and V were daily pretreated with L-carnitine (LC) at doses of 0.5, 1.0, and 2.0 g kg^?1 of the diet for 4 weeks prior to MCLR intraperitoneal injection. The results showed that MCLR alone led to a significant downregulation in immune response, including serum complement C3, lysozyme, and bactericidal activity. However, oxidative stress response: catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), and lipid peroxidation (LPO) levels were significantly increased. Similarly, gene expressions of inflammatory IL-1β, TNF-α, IFN I, and heat shock proteins (HSP70 and HSP90) were also upregulated after challenged with MCLR. However, LC pretreated group caused a significant elevation in immune response (C3, lysozyme, and bactericidal activity) and gene expressions of inflammatory IL-1β, TNF-α, IFN I, and heat shock proteins (HSP70 and HSP90) after MCLR stress. Antioxidant activities (CAT, SOD, GSH, GPx, and LPO) were returned to background levels at 96 h after MCLR challenge. Strikingly, LC supplementation at 2.0 g kg^?1 has been considered the optimum for common carp since it exhibited enhancement of immune response and antioxidant activity over the level 0.5 and 1.0 g kg^?1, and even better than that of control level. It was concluded that LC as a functional feed additive significantly inhibited the progression of MCLR-induced immunotoxicity and oxidative stress in common carp.     

Induced ovulation of yellow catfish (Pelteobagrus fulvidraco) using a combination of a gonadotrop‐releasing hormone analogue and domperidone

The effects of an intraperitoneal hormone injection of gonadotropin‐releasing hormone agonist (D‐Ala⁶, Pro⁹‐NEt GnRHa) alone or in combination with a dopamine antagonist, domperidone (DOM), on ovulation induction in yellow catfish Pelteobagrus fulvidraco were tested. The hormone treatments were as follows: 6 mg kg⁻¹ body weight (BW) of carp pituitary extract as a positive control, GnRHa 10, 20, 40 and 80 μg kg⁻¹ BW and a combination of GnRHa and DOM as follows: 10 μg+5 mg, 20 μg+10 mg, 40 μg+20 mg and 80 μg+40 mg kg⁻¹ BW. Physiological saline (0.7% NaCl) was used as a negative control. Significant differences in the ovulation ratio, latency period and ovulation index (OI) were observed among treatments (P<0.05). The combination of GnRHa and DOM at doses of 40 μg+20 mg kg⁻¹ BW had higher values of the ovulation ratio and OI, and a shorter latency period compared with other treatments. The highest OI in GnRHa treatments was only 56.67%, suggesting a dopaminergic tone on gonadotropin secretion in this fish at the pre‐ovulatory stage. Therefore, ovulation can be successfully induced in yellow catfish with 40 μg kg⁻¹ GnRHa+20 mg kg⁻¹ DOM without affecting the egg quality.     

Quantitative dietary isoleucine requirement of juvenile Pacific white shrimp,Litopenaeus vannamei (Boone) reared in low-salinity water

This study was designed to determine the isoleucine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low-salinity water (0.50–0.70 g L^?1). Six diets were formulated to contain 410 g kg^?1 crude protein with fish meal, peanut meal and pre-coated crystalline amino acids with different concentration of l-isoleucine (9.35, 11.85, 14.35, 16.85, 19.35, and 21.85 g kg^?1 dry diet, defined as diet I1, diet I2, diet I3, diet I4, diet I5 and diet I6, respectively.). Each diet was randomly assigned to triplicate treatments of 30 shrimps (0.43 ± 0.005 g), and the feed trial lasted for 8 weeks. The results indicated that the weight gain significantly increased with increasing isoleucine concentration up to 14.35 g kg^?1 (diet I3), whereas it was reduced in the treatments exceeding 16.85 g kg^?1 isoleucine (diet I4) significantly (P < 0.05). Moreover, the highest body protein deposition and protein efficiency ratio, and the lowest feed conversion ratio, haemolymph aspartate aminotransferase and alanine aminotransferase activities were also found at treatment I3–I4 (P < 0.05). And the haemolymph urea nitrogen concentration of shrimps-fed diet I6 was particularly higher than those fed with diets I1–I5 (P < 0.05). The results of polynomial regression based on weight gain, feed efficiency and body protein deposition indicated that the optimal dietary isoleucine requirement for L. vannamei reared in low-salinity water was 15.95 g kg^?1 isoleucine of dry diet, correspondingly 38.81 g kg^?1 of dietary protein.     

Modulation of appetite,lipid and glucose metabolism of juvenile grass carp (<Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>) by different dietary protein levels

This study was undertaken to explore the systemic metabolic strategies of juvenile grass carp (Ctenopharyngodon idellus) to maintain growth when fed with different dietary protein levels. The optimal growth group and two growing discomfort groups were selected through the basic data, to explain the growth difference from appetite regulation and lipid and glucose metabolism perspective. Three experimental diets were formulated with three dietary protein levels at 200.3, 296.1 and 442.9 g kg^?1, named P1, P2 and P3, respectively. Juvenile grass carp (initial body weight 12.28 ± 0.14 g) were fed with three diets with 3 replications per dietary treatment in an indoor recirculation system for an 8-week feeding trial. Fish fed with diet P2 dietary group showed significantly higher WG, SGR, FI and PER than other groups. Compared with other groups, mRNA expressions of NPY, Y8a and Y8b in fish fed with P2 significantly down-regulated, while the expressions of CCK and CART in fish fed with P3 significantly down-regulated (P < 0.05). With increasing dietary protein levels, G6Pase, GK, PK and PEPCK were all significantly inhibited (P < 0.05). For lipid metabolism, the mRNA expression of ACC in P1 dietary group was significantly higher than P3 dietary group; besides, LPL expression in P3 group was significantly higher than other two groups (P < 0.05). PPARα expression in P2 was significantly lower than other groups (P < 0.05). These results suggested that grass carp fed with P2 (296.1 g kg^?1 protein level) showed highest weight gain, contributed to more balanced nutrient metabolism and appetite regulation. Too high dietary protein (442.9 g kg^?1) should be avoided because it induced lowest PER, body lipid and liver lipid, and inhibited glucose and lipid metabolism in juvenile grass carp.     

Effects of replacing fish meal with rubber seed meal on growth,nutrient utilization,and cholesterol metabolism of tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis> × <Emphasis Type="Italic">O. aureus</Emphasis>)

A feeding trial was conducted to evaluate the effects of replacing fish meal with rubber seed meal (RSM) on growth, nutrient utilization, and cholesterol metabolism of tilapia (Oreochromis niloticus × Oreochromis aureus). Five experimental diets were formulated with 0, 150, 300, 450, and 600 g kg^?1 RSM replacing graded levels of fish meal, respectively. Each diet was randomly assigned to triplicate groups of 25 fish (initial average weight 65.3 g) per aquarium in a rearing system maintained at 29 ± 1 °C for 8 weeks. Dietary 150 g kg^?1 RSM inclusion did not affect the weight gain and daily growth coefficient, whereas these were depressed by a further inclusion. Additionally, feed efficiency ratio and protein efficiency ratio were not affected by dietary RSM inclusion regardless of inclusion level. However, the inclusion of 450 and 600 g kg^?1 RSM decreased the mid-intestinal trypsin, lipase, and amylase activities; the hepatic acyl-CoA/cholesterol acyl transferase; low-density lipoprotein receptor; and 3-hydroxy-3-methyl-glutaryl-CoA reductase activities. Similarly, dietary 600 g kg^?1 RSM inclusion inhibited the plasma catalase and hepatic glutathione peroxidase activities. These results indicated that 150 g kg^?1 RSM can be included in tilapia diets, whereas higher inclusion of RSM inhibited the growth rate, digestive enzyme activity, antioxidant capacity, and cholesterol metabolism.     

Fat deposition pattern and mechanism in response to dietary lipid levels in grass carp, <Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>

This study aimed to evaluate the fat deposition pattern and lipid metabolic strategies of grass carp in response to dietary lipid levels. Five isonitrogenous diets (260 g kg^?1 crude protein) containing five dietary lipid levels (0, 20, 40, 60, 80 g kg^?1) were fed to quadruplicate groups of 15 fish with initial weight 200 g, for 8 weeks. The best growth performance and feed utilization was observed in fish fed with lipid level at 40 g kg^?1. MFI and adipose tissue lipid content increased with increasing dietary lipid level up to 40 g kg^?1, and higher lipid level in diet made no sense. Fish adapted to high lipid intake through integrated regulating mechanisms in several related tissues to maintain lipid homeostasis. In the present study, grass carp firstly increased PPARγ and CPT1 expressions in adipose tissue to elevate adipocyte differentiation and lipolysis to adapt to high lipid intake above 40 g kg^?1. In liver, fish elevated hepatic lipid uptake but depressed biosynthesis of hepatic FAs, resulted in no difference in HSI and liver lipid content among the groups. Only in muscle, fish showed a significant fat deposition when the lipid intake above 40 g kg^?1. The excess lipid, derived from enhanced serum TC and TG contents, was more likely to induce deposition in muscle rather than lipid uptake by adipose tissue in grass carp fed with high dietary lipid, indicating the muscle of grass carp might be the main responding organ to high lipid intake.     

Dietary lipid concentrations influence growth,liver oxidative stress,and serum metabolites of juvenile hybrid snakehead (<Emphasis Type="Italic">Channa argus</Emphasis> × <Emphasis Type="Italic">Channa maculata</Emphasis>)

The study was conducted to evaluate the effect of dietary lipid levels on growth, liver oxidative stress, and serum metabolites of juvenile hybrid snakehead (Channa argus × Channa maculata). Five isonitrogenous (crude protein 420 g kg^?1) practical diets containing 58, 87, 115, 144, and 173 g kg^?1 crude lipid (named L58, L87, L115, L144, and L173, respectively) were fed to triplicate groups of 30 fish (mean initial weight 24 g) for 8 weeks. The results showed that the final body weight (58.68–78.81 g), specific growth rate (1.41–1.75 % day^?1), and protein efficiency ratio (1.66–2.64) increased significantly with the increasing dietary lipid levels. Liver lipid contents (71.65–101.80 g kg^?1) and crude lipid (52.10–83.63 g kg^?1) of whole body increased with increasing dietary lipid levels and reached the highest values in fish of L173. Fish of L173 showed lower alkaline phosphatase (23.81 King Unit gprot^?1) and catalase activities (4.44 U mgprot^?1) but higher malondialdehyde content (0.69 nmol mgprot^?1) in liver than the other groups. Higher alanine transaminase activity (8.20 U L^?1), aspartate transaminase activity (63.65 U L^?1), and triglyceride (0.29 mmol L^?1) in serum were observed in fish of L173 compared to the other treatments. Fish of L144 showed higher superoxide dismutase activity and glutathione peroxidase activities in liver than that of fish fed diet L58. Fish fed diet L58 showed lower total cholesterol (3.61 mmol L^?1), high-density lipoprotein cholesterol (1.39 mmol L^?1), and low-density lipoprotein cholesterol (0.46 mmol L^?1) in serum. These results suggested that juvenile snakehead (Channa argus × Channa maculata) achieved good growth performance with dietary lipid level 173 g kg^?1. Diet with 143 g kg^?1 lipid was more conductive to liver health. The appropriate dietary lipid supplementation needs to be determined in further studies.     

Effect of dietary garlic supplementation on lipid peroxidation and protein oxidation biomarkers of tissues as well as some serum biochemical parameters in common carp Cyprinus carpio

This study aims to investigate the effects of dietary garlic powder (25 and 50 g kg^?1 feed) supplementation for 6 weeks on lipid and protein oxidation biomarkers in various tissues as well as some blood biochemical parameters in common carp. Based on the present study results, serum malondialdehyde (MDA) concentrations were decreased following garlic supplementation, but the decrease was only significant (P < 0.05) in the group that received 50 g kg^?1 dietary garlic compared with the control group. Moreover, garlic at 50 g kg^?1 diet caused significant decrease in MDA values of liver and kidney. Additionally, the decreasing effect of garlic at 25 g kg^?1 diet on MDA values was only significant in liver. Protein carbonyl contents were only decreased significantly in muscle following garlic administration at 25 g kg^?1 diet. Serum aspartate aminotransferase activity decreased significantly in carp that received 25 g kg^?1 dietary garlic. Moreover, alkaline phosphatase activity decreased significantly in carp fed diets containing 25 and 50 g kg^?1 garlic. On the other hand, garlic supplementation had no significant effect on gamma-glutamyl transferase activity and total protein, albumin, and creatinine concentrations. The results of the present study indicate that garlic powder has potential to decrease oxidative stress to some extent by reducing lipid and protein oxidation in some tissues of common carp.     

Effect of gonadotropin hormonal stimulation on out-of-season propagation success of different year classes of indoor-reared pikeperch (Sander lucioperca (L.))

Three trials of hormonally induced out-of-season spawning of cultured pikeperch were performed. Two preparations containing human chorionic gonadotropin (hCG) (groups Bg-4 and Pl-4) were applied in experiment I. Injections of preparations containing hCG either alone (group P1-3) or in combination with pregnant mare serum gonadotropin (PMSG) of different producers (groups Sr-3 and Pg-3) were applied in experiment II. Spawning effectiveness was determined for four age groups (2+ to 5+) of pikeperch stimulated with hCG (groups Pl-2–Pl-5) in experiment III. The females from all the experimental groups were stimulated once with a single dose of hormone at 300 IU kg^?1 body weight (BW). Females from the control group were injected with a 0.9 % solution of NaCl (group C). The working fecundity (CF; % of BW), latency time (LaT; h), and eyed-egg survival (EES, %) were determined. No progress in oocyte maturation was noted among the females from group C. Significant differences were noted in LaT, which was lower in group Pl-3 than in groups Sr-3 and Pg-3. The youngest fish (2+) matured significantly more slowly and exhibited significantly lower values of the CF and EES indexes in comparison with older fish (LaT 102 vs 75–80 h; CF 5.4 vs 10.4–11.2 % BW; EES 47 vs 70–77 %). The hormonal preparations used had a positive impact on the ovulation and spermiation of the cultured pikeperch. No improvement in the effectiveness of out-of-season spawning was noted when combined preparations of hCG and PMSG were used.     

Dietary arginine requirement of fingerling Indian catfish (Heteropneustes fossilis, Bloch)

An 8-week feeding trial was conducted to determine the dietary arginine requirement of fingerling Indian catfish, Heteropneustes fossilis (6.25 ± 1.30 cm, 4.8 ± 0.65 g). Six isonitrogenous (400 g Kg^?1) and isoenergetic (17.90 kJ g^?1) amino acid test diets were formulated with gradation of 2.5 g Kg^?1 containing graded levels of l-arginine (8.5–21.0 g Kg^?1, dry diet). Fish were randomly stocked in triplicate groups, in 75-l circular trough with flow-through system and fed experimental diets at 4 % BW/day at 0800 and 1800 h. Maximum live weight gain (277 %), best feed conversion ratio (FCR) (1.52) and protein efficiency ratio (PER) (1.64) were obtained in fish fed diet containing 16.0 g Kg^?1 arginine. However, quadratic regression analysis of live weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary arginine at 16.80, 16.30, 16.11 and 16.10 g Kg^?1 of dry diet, respectively. Significantly (p < 0.05) higher whole body protein content, minimum carcass moisture and intermediate carcass fat contents were recorded at 16.0 g Kg^?1 dietary arginine diet. Ash content remained insignificantly (p > 0.05) low among all the treatments except at diet I and diet II. Based on the above results, it is recommended that the diet for young H. fossilis should contain arginine at 16.32 g Kg^?1, dry diet, corresponding to 40.80 g Kg^?1 dietary protein for optimum growth and efficient feed utilization.     

Dietary amino acid l-tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch), estimated by growth and haemato-biochemical parameters

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g^?1) and isoenergetic (17.90 kJ g^?1) amino acid test diets were formulated with gradation of 0.1 g 100 g^?1 containing graded levels of l-tryptophan (0.04–0.54 g 100 g^?1, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g^?1 tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g^?1 of dry diet, respectively. Significantly (P < 0.05) higher body protein, minimum moisture and intermediate fat contents were recorded at 0.34 g 100 g^?1 dietary tryptophan diet. Ash content was not significantly different (P > 0.05) among treatments except for diets 0.04 and 0.14 g 100 g^?1. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g^?1, dry diet, corresponding to 0.80 g 100 g^?1 dietary protein for optimum growth and efficient feed utilization.