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1.
Aquaculture of Spinibarbus denticulatus (Oshima, 1926), a fish species indigenous to North Vietnam and Eastern China, is constrained by lack of fingerlings for stocking ponds and cages. As these fish do not naturally breed in captivity, carp pituitary extract (CPE), luteinizing hormone-releasing hormone analogue (LHRHa) with domperidone (DOM) and human chorionic gonadotropin (HCG) were administered at various doses to induce ovulation. A first set of experiments evaluated the response to LHRHa (30, 40 and 50 μg kg−1) with or without DOM (10 mg kg−1), CPE (20, 30 and 40 mg kg−1) and HCG (3000, 4000 and 5000 IU kg−1). A second set of experiments evaluated the dose response to LHRHa (30, 35, 40 and 50 μg kg−1) primed with 6 mg kg−1 of CPE, and HCG (3000, 3500, 4000, 5000 IU kg−1) primed with 6 mg kg−1 of CPE. The treatment groups were compared with each other and the control (injected with 0.9% saline solution). Only 25% and 50% ovulation resulted when treated with LHRHa at 40 and 50 μg kg−1, whereas 100% ovulation was achieved with an addition of DOM to LHRHa. Both 30 and 40 mg kg−1 CPE induced 100% ovulation. However, HCG (4000 and 5000 IU kg−1) induced ovulation in only 33% of females. When primed with CPE, the minimum dose of LHRHa required was 35 μg kg−1 to achieve 70% ovulation. Priming HCG with CPE also resulted in 100% ovulation, and the minimum effective dose of HCG to induce ovulation was 3500 IU kg−1 with 60% ovulation. Fertilization and hatch rates observed in this study with different hormonal stimulation were high (80–93%). The results indicate that while the use of combined hormone strategy has no apparent advantage over a single hormone strategy, LHRHa+DOM (40 μg kg−1+10.0 mg kg−1) and CPE (30 mg kg−1) are most effective in consistently inducing ovulation and thus can be used for commercial hatchery production of S. denticulatus larvae.  相似文献   

2.
Kutum Rutilus frisii kutum (Kamenskii, 1901), Cyprinidae is an endemic fish of the Caspian Sea. Iranian Fisheries Organization (Shilat) produce up to 200 million fry (1–2 g body weight (b.w.)) to restock the Caspian Sea population annually. Some of these fry are produced by spawning induction in broodfish by carp pituitary extract (CPE). The objective of this study was to assay the effectiveness of the gonadotropin releasing hormone analogue (d ‐Ala6, Pro9‐Net GnRH) alone or in combination with metoclopramide (MET), a dopamine antagonist, on the percentage of ovulated females, latency period, ovulation index and fertilization success. The following hormone treatments were tested: single injection of 2 mg kg?1 b.w. of CPE as a positive control, GnRHa alone 20 and 40 μg kg?1 b.w. and combination of GnRHa and MET as follows: 5 μg+2.5 mg, 10 μg+ 5 mg and 20 μg+10 mg kg?1 b.w. Negative control group was injected with 0.7% saline. The percentage of ovulated females, ovulation index and fertilization success were 90%, 71.3±1.24%, 68.4±2.3%, respectively, in the group treated with GnRHa+MET at a dose of 20 μg+10 mg kg?1 b.w. and were significantly higher than those in the positive control (60%, 64.5±0.23%, 69.1±4.5%) (P<0.05). However, the latency period in this group was longer than that in the positive control (P<0.05). Only 20% and 40% fish ovulated in groups that received 20 or 40 μg kg?1 b.w. GnRHa. No fish ovulated in the negative control.  相似文献   

3.
Wild female catfish Silurus asotus (Linnaeus, 1758) were injected with domperidone (DOM) alone, [d ‐Ala6, Pro9 Net]‐luteinizing hormone‐releasing hormone (LHRH‐A) alone once or twice, LHRH‐A plus DOM once or twice simultaneously at 6‐h intervals, LHRH‐A plus carp pituitary extract (CPE) twice simultaneously at 6‐h intervals and LHRH‐A plus human chorionic gonadotropin (HCG) twice simultaneously 6 h apart respectively. The results indicated that injection of LHRH‐A at a dosage of 0.01–0.02 μg g?1 body weight (BWt) alone induced a low but significant increase in serum gonadotropin (GtH) (P<0.05) and resulted in a very low ovulation rate, while DOM at a dosage of 5 μg g?1 BWt alone did not induce an increase in the serum GtH levels and ovulation; in contrast, LHRH‐A at a dosage of 0.01 μg g?1 BWt plus DOM at a dosage of 5 μg g?1 BWt (termed the Linpe technique) increased the serum GtH (P<0.05) significantly and induced an ovulatory rate of 100%, while LHRH‐A plus CPE or HCG resulted in an increase in the serum GtH (P<0.05) and high ovulatory rate, although the latency period was longer when fish were given LHRH‐A plus HCG or CPE.  相似文献   

4.
Hatchery-produced white bass (Morone chrysops) and striped bass (M. saxatilis) reared to maturity in a commercial aquaculture facility, were successfully spawned using controlled-release delivery systems containing the gonadotropin-releasing hormone analog DAla6, Pro9[NEt]-GnRH (GnRHa). Two-year-old white bass females (mean weight, 0.81 kg) were implanted with different polymer-based, GnRHa delivery systems at doses ranging from 40 to 89 μg GnRHa kg−1 body weight. GnRHa treatment on 20 February 1994, when females contained oocytes up to 720 μm in diameter, induced ovulation of all fish between 35 to 82 h after treatment. The white bass eggs produced were fertilized with sperm from striped bass for the production of sunshine bass. An average of 294500 eggs kg−1 were produced, with a mean fertility of 81.2%, 24 h survival of 46.5%, and overall hatching success of 45%. Survival from hatch to 30 days post-hatch was 78% and the fry weighed between 0.07 and 0.1 g. Overripening of eggs began within 1 h from ovulation and maximum fertilization (60%) was observed when eggs were stripped 0.5 h after ovulation. Fertilization success decreased thereafter to 31% and 10% by 1 h and 3 h after ovulation, respectively. Control fish not treated with GnRHa did not show any signs of final oocyte maturation during the period of the study. GnRHa administration via controlled-release delivery systems appears to be a very effective method for inducing high fecundity ovulation of captive white bass broodstocks, and producing eggs of high fertility and hatching success.  相似文献   

5.
The acceleration of final oocyte maturation and ovulation is recognized as a principal process in Caspian kutum Rutilus frisii kutum, a commercial and valuable species in Caspian Sea. The aim of this study was to evaluate the effects of catecholaminergic pharmaceutics which include Salbutamol (β2‐adrenergic receptor agonist), Metoprolol (β1‐adrenergic receptor antagonist), Clozapine and Olanzapine (the third generation of D4 and D2 dopamine receptor antagonists) which can be more efficient than the first and second generations, in combination with Buserelin ([D‐Ser(tBu)6,Pro9‐NEt]‐GnRHa) and Ovaprim (D‐Ala6,Pro9‐Net)‐sGnRH+Domperidone on ovulation and spawning induction in Caspian kutum. One hundred eight adult females were injected once with Buserelin Acetate (BUS) 5 μg kg?1 BW, Ovaprim 0.5 mL kg?1 BW, Salbutamol Sulphate (SLB) 4 mg kg?1 BW, Olanzapine (OLZ) 5 mg kg?1 BW, Clozapine (CZ) 12 mg kg?1 BW and Metoprolol Tartrate (MTP) 5 mg kg?1 BW, being divided into 12 groups: group 1, intact (negative control); group 2, Ovaprim (positive control); group 3, OLZ+SLB; group 4, OLZ+MTP; group 5, OLZ+BUS; group 6, CZ+SLB; group 7, CZ+MTP; group 8, CZ+BUS; group 9, OLZ+BUS+SLB; group 10, OLZ+BUS+MTP; group 11, CZ+BUS+SLB and group 12, CZ+BUS+MTP (N = 9). The results showed that the highest mean value in ovulation success, ovulation index, fertilization success, relative fecundity and the number of eggs belonged to Ovaprim treatment. On the other hand, spawning was successful in OLZ+BUS+SLB and CZ+BUS treatments (P < 0.05), whereas it was lower in CZ+MTP, CZ+BUS+MTP and OLZ+BUS than the other treatments. Therefore, it could be concluded that Clozapine and Olanzapine potentiated the effect of Buserelin treatment in ovulation and spawning induction, while Metoprolol blocked the stimulatory effects of GnRHa, Clozapine and Olanzapine. Salbutamol also can amplify stimulatory effect of all mentioned pharmaceutics.  相似文献   

6.
An experiment was conducted to induce ovulation in Asian catfish, Clarias batrachus, by a single injection of SGnRHa (d ‐Arg6, Trp7, Leu8, Pro9, Net) in combination with domperidone. The effects of latency periods, 11, 14, 17, 20 and 23 h, and doses of inducing agent, 10 μg SGnRHa+5 mg domperidone, 20 μg SGnRHa+10 mg domperidone, 30 μg SGnRHa+15 mg domperidone and 40 μg SGnRHa+20 mg domperidone kg?1 body weight, were studied on the total egg output, stripping response, fertilization, hatching and normal larval production. The highest (P<0.05) number of eggs were stripped at 23 h of post injection of 20 μg SGnRHa+10 mg domperidone kg?1 female body weight. The highest (P<0.05) stripping response was observed when the females were stripped at 20 and 23 h latency, at all dose levels of the inducing agent. The eggs stripped at 11 h latency did not fertilize, and hence did not hatch irrespective of administration of any dose levels of the inducing agent. The fertilization and hatching per cent of eggs had significantly increased (P<0.05) with increase in latency period to 14–23 h at a dose of 20 μg SGnRHa+10 mg domperidone. The latency period of 14–17 h, and dose of 20 μg SGnRHa+10 mg domperidone and 30 μg SGnRHa+15 mg domperidone kg?1 of female, was found to be suitable to obtain best spawning performance, and good‐quality egg and larval production in C. batrachus.  相似文献   

7.
In this study, the effect of gonadotropin‐releasing hormone agonist (GnRHa) injection on milt production in spent rainbow trout was investigated. On day 0, 25 newly matured male rainbow trout (Oncorhynchus mykiss) were stripped manually, and sperm quantity (vol: mL fish?1) and quality, spermatocrit (%), sperm count (cell mL?1), motile sperm percentage and motility duration (s) were evaluated. After stripping, fish were randomly divided into five groups: intact; sham (injected with propylene glycol as a hormone vehicle); and groups receiving 4, 8 or 16 μg kg?1 BW of [d ‐Ala6 Des‐Gly10] mGnRHa. On day 7, the fish were stripped again and the same sperm characteristics as on day 0 were measured. At the beginning of the experiment, there were no significant differences in any of the sperm quantity characteristics between groups. On day 7, expressible milt volume was significantly reduced compared with day 0 (P<0.05, t‐test) in the intact and sham groups but milt quality remained the same (P>0.05, t‐test). The present study shows that GnRHa injection with a concentration as low as 4 μg kg?1 BW after first stripping could prevent a significant reduction in milt quantity collected 7 days later without any adverse effects on sperm quality.  相似文献   

8.
Channel catfish were fed practical corn‐soybean meal diets for 10 weeks that contained various weighed amounts of ground, dried field corn contaminated with 20 mg deoxynivalenol (DON) kg−1. Weighed amounts of DON corn were blended with weighed amounts of ground, clean corn that contained no DON (0 mg kg−1) to yield five diets that had 0, 2.5, 5.0, 7.5 and 10.0 mg DON kg−1 of diet. Results show that catfish fed diets that contained DON for 7 weeks did not experience lower weight gains or poorer feed conversion ratios that were significantly (P > 0.05) different from control‐fed fish. Mortality of catfish during the 21‐day post‐challenge period indicate that catfish fed diets containing DON‐contaminated corn that provided at least 5.0 mg DON kg−1 of diet had significantly (P < 0.05) lower mortality than catfish fed the control diet or the diet that provided 2.5 mg DON kg−1 of diet. The presence of DON‐contaminated corn in the experimental diets did not significantly (P > 0.05) alter fish body weight gains and appeared to provide a protective effect for channel catfish challenged with the pathogenic bacterium Edwardsiella ictaluri.  相似文献   

9.
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.  相似文献   

10.
This study addresses rapid methods to identify mature channel catfish, Ictalurus punctatus, females for induced spawning with luteinizing hormone releasing hormone analog (LHRHa) and common carp pituitary extract (CPE) and the effects of stage of maturity, hormone dose, season, and cannulation before hormone injection. Hormonal intervention is the most effective method for inducing maturation and spawning in channel catfish × blue catfish, Ictalurus furcatus, hybrids. A total of 80 mature channel catfish were staged for maturity based on secondary sexual characteristics and 20–30 oocytes cannulated to ascertain their maturation stage based on the position of gonadal vesicle. Twenty females were randomly assigned to one of the four hormone regimes (priming + resolving dose): CPE 2 + 8 mg/kg (CPEC); LHRHa 20 + 40 µg/kg (LHRHaL); LHRHa 20 + 60 µg/kg (LHRHaM); and LHRHa 20 + 80 µg/kg (LHRHaH) and a fifth treatment consisted of 20 females selected based on apparent maturity as evidenced by external appearance were injected with CPE, 2 + 8 mg/kg without cannulation (CPEO). Two trials were conducted in early part of the spawning season and two trials in peak season. External methods to identify maturity correlated (r = 0.63) with that of “germinal vesicle position” method to identify the stage of maturity in females. Mean percent of females that ovulated, hatched, and fry produced per kg body weight did not differ (P > 0.05) among the five hormone treatments. The mean percent females that ovulated was higher (P < 0.05) for CPE‐induced females that were identified as “excellent” females based on external examination. The performance of cannulated females did not differ (P > 0.05) with that of non‐cannulated catfish. The mean egg quality of hormone‐induced females and percent of females ovulated in response to hormone treatment established a weak but significant linear relationship (Y = 3.85 + 0.008 × ovulation, r2 = 0.39, P < 0.05).  相似文献   

11.
To induce synchronized ovulation, migrating wild Caspian brown trout (Salmo trutta caspius) females were treated with two interperitoneal injections of Des‐Gly10, d ‐Ala6 LHRH (LHRHa), given 3 days apart. Two injections of 100 μg kg?1 body weight of this hormone effectively induced ovulation. Within 27 days from the second injection, all fish injected with 100 μg kg?1 LHRHa had ovulated compared with 54.5% of the controls. The mean time to ovulation was reduced significantly (P<0.05) from 31.67±4.84 days in control fish and 28.83±7.31 days in sham‐treated fish to 16.36±1.61 days in fish injected with 100 μg kg?1 LHRHa. The fertilization rate in 50 and 100 μg kg?1 LHRHa‐injected fish was significantly lower than that in the control fish (P<0.05). In fish injected with 50 and 100 μg kg?1 LHRHa, significant (P<0.05) changes in testosterone (T) and 17α‐hydroxyprogestrone (OHP) levels were observed. After the second LHRHa injection, the fish injected with 100 μg kg?1 showed the highest serum levels of testosterone and OHP. These results demonstrate that the use of LHRHa can effectively reduce the mean time to ovulation and induce synchronized ovulation in Caspian brown trout.  相似文献   

12.
The effects of a single injection of mammalian superactive analogue [d ‐Ser(tBu)6,Pro9‐NEt]‐LHRHa (20 μg/ kg?1) combined with the dopamine antagonist, haloperidol (HAL, 0.5 mg kg?1), for induction of ovulation in the koi carp broodstocks were determined under routine hatchery conditions. The results were compared with classic carp pituitary extract (CPE, double injection) application (water temperature 22 °C). Physiological saline (0.7% NaCl)‐injected fish were used as a control group and no ovulation occurred in this group. The spawning ratio was high in the LHRHa+HAL treatment group and in the CPE treatment group (6/7 and 5/7 respectively). The latency period was 14–16 h in the LHRHa+HAL treatment group and 12–14 h in the CPE treatment group (after the second injection). There was no difference between the two ovulating groups with respect to the spawning index (the weight of eggs as a percentage of female body weight) and fertilization rate of eggs (P>0.05). As a result, ovulation can be induced successfully in koi carp broodstocks with 20 μg kg?1 [d ‐Ser(tBu)6,Pro9‐NEt]‐LHRHa+0.5 mg kg?1 HAL treatment in a single injection without decreasing the egg quality. Application of this combination can be useful for hatchery and broodstock management in koi carp culture.  相似文献   

13.
In the present study, the efficacy of Letrozole, a potent nonsteroidal aromatase inhibitor (AI), on gonadal sex differentiation and sex reversal was examined in bluegill sunfish (Lepomis macrochirus). In Experiment 1, using AI diet treatments (50, 150, 250 and 500 mg kg−1) from 30 to 90 days posthatch (dph), AI interrupted ovarian cavity formation at a dose of 500 mg kg1 diet and one intersex fish was identified in this group. The proportions of males in all the treated groups were significantly higher than those in the control group. In Experiment 2, using AI immersion treatments (250, 500 and 1000 μg L−1) during 30–50 dph, the treated groups of 500 and 1000 μg L−1 produced significantly more males than the control and 250 μg L−1 groups. Histological examination revealed no differences in ovary or testis tissue between control and AI‐treated fish. There were no significant differences detected in body weight and length among the AI treated and control groups (P>0.05) for both experiments. The results from these two experiments suggest that inhibition of aromatase activity by AI could influence sex differentiation in bluegill sunfish.  相似文献   

14.
The effects of dopamine on the secretion of two sturgeon gonadotropins (stGTH I and stGTH II) in sexually mature male white sturgeon (Acipenser transmontanus) were evaluated. In Experiment I, sturgeon were given intraperitoneal injections of physiological saline (PS), dopamine (100 mg kg−1), the gonadotropin releasing hormone analog D-Ala6-des-Gly10-GnRH ethylamide (GnRHA) (10 μg/kg−1), and a combination of GnRHa and dopamine. Fish receiving only GnRHa had significantly higher (p < 0.05) concentrations of plasma stGTH I and stGTH II compared to fish receiving PS, dopamine, or a combination of GnRHa and dopamine. Two hours following its administration, dopamine was effective in decreasing plasma concentrations of both stGTHs that were previously elevated by GnRHa. Dopamine or PS administered by themselves did not alter plasma concentrations of either stGTH. In Experiment II, sturgeon injected intraperitoneally with a combination of GnRHa and pimozide had significantly higher (p < 0.05) concentrations of plasma stGTH I and stGTH II compared to males receiving GnRHa or pimozide alone. While this effect of GnRHAa + pimozide was observed in the spring, no such potentiation was seen in these fish during the summer (Experiment III). These results represent the first evidence of dopaminergic inhibition of GnRH-induced pituitary gonadotropin secretion in Chondrostean fish.  相似文献   

15.
Ovulation was stimulated in four groups of European catfish, Silurus glanis L., using injections of des-Gly10, [D-Ala6]-LHRH Ethylamide (20 μg kg–1) and pimozide (10 mg kg–1), Ovaprim (0.33 mL kg–1), and carp pituitary extract (4 mg kg–1, in one or two doses). A higher percentage of ovulating females (producing eggs of sufficient quality) was found after the LHRH-a and Ovaprim treatments (100% and 80%) in relation to fish treated with the pituitary extract (60% and 66.67%). The greatest weight of eggs was obtained in the case of repeated hypophysation and LHRH-a (1299.69 and 1298.57 g, respectively), and the smallest after single hypophysation (1144.08 g). After 60 h of incubation, the best quality of eggs was found in the group treated with Ovaprim (62.9% of live embryos) and the poorest in the two groups which underwent hypophysation (50.41% and 50.75%). No statistically significant effect by the ovulation stimulators on the characteristic qualitative and quantitative traits of obtained eggs was ascertained.  相似文献   

16.
The culture of Litopenaeus vannamei in inland low salinity waters is currently being practiced in various countries around the world. These environments are often deficient in key ions essential for normal physiological function, including potassium (K+) and magnesium (Mg2+). Farmers have sometimes been able to counteract ionic deficiencies in the water profile by adding mineral salts containing sources of K+ and Mg2+. The purpose of this study was to explore the possibility of correcting deficiencies of K+ and Mg2+ in the water profile with dietary supplementation of these minerals. Two separate 7‐week experiments were conducted in 4.0 g−1 artificial low salinity water to evaluate the effects of mineral supplements (K+, Mg2+ and NaCl) to diets of L. vannamei reared in low salinity waters. In trial 1 seven diets were formulated (10 g NaCl kg−1, 20 g NaCl kg−1, 150 mg kg−1 Mg2+, 300 mg kg−1 Mg2+, 5 g K+ kg−1, 10 g K+ kg−1, and a basal diet to serve as a control). Minerals were added in the form of purified potassium chloride (KCl), magnesium chloride (MgCl2·6H2O) and NaCl. Trial 2 evaluated the use of a coating agent for the Mg2+ and NaCl treatments, while a K+ amino acid complex was utilized in the K+ treatments to reduce mineral leaching. Trial 2 was performed using similar treatment levels as trial 1. Shrimp survival and growth were assessed in both experiments. Results from trial 1 indicated no significant differences in survival, growth or percent weight gain. Results from trial 2 revealed no significant differences in survival and growth in the NaCl and Mg2+ treatments. However, significant differences in growth (P < 0.05) were observed when using the 10 g K+ kg−1 treatment, suggesting that dietary supplementation of a K+ amino acid complex may help improve growth of the species in low salinity waters.  相似文献   

17.
The purpose of this study was to verify the effect of dietary Ca2+ on the growth and survival of silver catfish fingerlings (Rhamdia quelen) exposed to different water pH (5.5, 7.5 and 9.0). Silver catfish fingerlings were randomly placed in a thermoregulated water re‐use system with twelve 250 L‐tanks, two 1000 L‐biofilters and a 2000 L‐reservoir with a medium flow of 3.84 L min?1 tank. Stocking density was 0.16 fingerlings L?1. To prepare the treatment diets, the control diet (0.8 g kg?1 Ca2+) was supplemented with CaCO3 to yield experimental diets with 6.4, 9.5 and 23.9 g kg?1 Ca2+. There were three replicates/treatments. Survival was more than 93.9% in all treatments. Exposure of silver catfish fingerlings to alkaline or acid water reduced growth, and this effect was not ameliorated by dietary Ca2+ supplementation. Moreover, when fingerlings were maintained in water with pH 7.5, the best dietary Ca2+ range for silver catfish fingerling growth was 0.8–6.4 g kg?1.  相似文献   

18.
Hybrid catfish (channel catfish Ictalurus punctatus × blue catfish Ictalurus furcatus) display characteristics that are favourable to aquaculture production. Low hatch percentages are a principal reason this hybrid is not used widely in the catfish industry. This study was conducted to determine whether additional food source rich in lipids may lead to a higher quality egg production. A 10‐week feed trial was conducted in ponds in Auburn, AL. A total of 219 female Kansas Select channel catfish were stocked into nine ponds, 0.04 ha in size. Three dietary treatments were randomly allocated to the ponds. Diet‐1 was a standard 60 g kg?1 lipid floating catfish feed. Diet‐2 was the same feed supplemented with forage fish at ～28 kg ha?1. The third diet was the aforementioned catfish feed topcoated with 20 g kg?1 lipid [10 g kg?1 menhaden fish oil, 5 g kg?1 high docosahexaenoic acid (DHA) oil and 5 g kg?1 high arachidonic acid oil]. Results indicate that brood fish fed the high lipid diet spawned larger egg masses and had larger eggs both in weight and in diameter, with increased complements of fatty acids such as DHA, eicosapentaenoic acid and total n‐3 fatty acids. The neutral and polar lipid fractions are also presented.  相似文献   

19.
In spite of interest in the cultivation of the pejerrey fish Odontesthes bonariensis (Cuvier & Valenciennes 1835), there are few studies on subjects required to advance this activity. One of the problems is the synchronization of female and male maturation to provide eggs and sperm for larval production. The low volume of expressible milt, either in wild or culture fish, is a major problem. The aim of this work was to study the effectiveness of the administration of different hormones on sperm production in pejerrey. Milt production was enhanced by the injection of human chorionic gonadotropin (hCG) (16.7‐fold increase, 625 IU kg?1), carp pituitary extracts (13.5‐fold increase, 30 mg kg?1), salmon pituitary extracts (12.8‐fold increase, 30 mg kg?1), salmon‐type gonadotropin‐releasing hormone analogue (GnRH) (16.7‐fold increase, 10 μg kg?1) and mammalian‐type GnRH analogue (10.8‐fold increase, 20 μg kg?1). Sperm concentration, motility and the fertilization rate were not statistically different compared with control groups. It was also demonstrated that sperm could be obtained off‐season. Taken together, hCG is recommended to stimulate pejerrey spermiation because it is effective in low doses is inexpensive and is widely available.  相似文献   

20.
An 8‐week feeding trial was conducted to determine the effects of dietary methionine level on juvenile black sea bream Sparus macrocephalus. Fish (initial body weight: 14.21 ± 0.24 g) were reared in eighteen 350‐L indoors flow‐through circular fibreglass tanks (20 fish per tank). Isoenergetic and isonitrogenous diets contained six levels of L‐methionine ranging from 7.5 to 23.5 g kg−1 of dry diet in 3.0 g kg−1 increments at a constant dietary cystine level of 3.1 g kg−1. Growth performance and feed utilization were significantly influenced by dietary methionine levels (P < 0.05). Maximum weight gain (WG), specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio and protein productive value (PPV) occurred at 17.2 g methionine kg−1 diet, beyond which they showed declining tendency. Protein contents in whole fish body and dorsal muscle were positively correlated with dietary methionine level, while muscle lipid content was negatively correlated with it. Apparent digestibility coefficients (ADCs) of dietary nutrients were significantly affected by dietary treatments except for ADCs of crude lipid. Fish fed the grade level of methionine demonstrated a significant improvement in whole‐body methionine content, total essential amino acids (∑EAA), total non‐essential amino acids (∑NEAAs) and ∑EAA/∑NEAA ratio (P < 0.05). Regarding serum characteristics, significant differences were observed in total cholesterol, glucose and free methionine concentration (P > 0.05), while total protein level and triacylglycerol concentration kept relatively constant among treatments (P < 0.05). Analysis of dose response with second‐order polynomial regression on the basis of either SGR or PPV, the optimum dietary methionine requirements of juvenile black sea bream were estimated to be 17.1 g kg−1 of diet (45.0 g kg−1 methionine of protein) and 17.2 g kg−1 of diet (45.3 g kg−1 methionine of protein) in the presence of 3.1 g kg−1 cystine, respectively.  相似文献   

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