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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.
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.  相似文献   

3.
Gastrointestinal and serum absorption of astaxanthin was studied in rainbow trout, Oncorhynchus mykiss (Walbaum) (217 ± 2 g) fed diets supplemented with either esterified astaxanthin (from Haematococcus pluvialis) or free astaxanthin (synthetic, as 8% w/w beadlets) at similar levels (50 mg kg?1). After 56 days of feeding, there was a significant difference (P = 0.0582) between steady‐state serum astaxanthin concentrations for fish fed free (2.0 ± 0.3 μg mL?1) or esterified astaxanthin (1.3 ± 0.1 μg mL?1) at the 90% confidence level. However, following ingestion of a single meal supplemented with free or esterified astaxanthin, the rates of astaxanthin absorption into serum were not significantly different (P > 0.1) (0.8 ± 0.2 µg mL?1 h?1 and 1.0 ± 0.4 µg mL?1 h?1 respectively). In fish fed both free or esterified astaxanthin, higher absorption (P < 0.05) of astaxanthin by the ileal (0.8 ± 0.14 μg g?1 and 0.9 ± 0.15 μg g?1 respectively) compared with the posterior (0.2 ± 0.01 μg g?1 and 0.3 ± 0.14 μg g?1 respectively) intestine was recorded. This confirmed the role of the anterior intestine in carotenoid absorption. Non‐detectable levels of esters in digesta taken from the hind intestine suggest the anterior intestine is also the primary region for ester hydrolysis.  相似文献   

4.
The effectiveness of common carp pituitary extract (CPE), luteinizing hormone releasing hormone analogue (LHRH‐A2) injections and LHRH‐A2 implants for spawning induction in female sturgeon, Huso huso was examined. In the first trial, fish were injected with 7% physiological saline (control), 50 mg kg?1 CPE or LHRH‐A2 at 3.5, 7, 8 or 10 μg kg?1. In the second trial, fish were treated with LHRH‐A2 cholesterol pellet implants containing 0, 3.5, 7, 8 and 10 μg kg?1 LHRH‐A2. Ovulated eggs were removed using a minimally invasive surgical technique and were artificially fertilized. Injection of CPE and LHRH‐A2 at doses of 3.5, 7, 8 and 10 μg kg?1 resulted in the number of ovulated fish more than LHRH‐A2 implants (similar doses) or controls, although there was no significant difference at doses of 8 and 10 μg kg?1 (P ≥ 0.05). The latency period of fish receiving CPE and LHRH‐A2 injections was approximately 20 h, which was significantly lower than in fish receiving LHRH‐A2 implants (P ≤ 0.05). Furthermore, there were no significant differences in rates of fertilization or hatching among the progeny produced in any of the treatment groups (P ≥ 0.05). In conclusion, the data from this study could be useful for artificial propagation of not‐fully‐matured females of H. huso at sturgeon hatcheries.  相似文献   

5.
Pharmacokinetics and residue elimination of marbofloxacin (MBF) were studied in crucian carp (Carassius auratus, 250±30 g) kept at two water temperatures of 15 and 25 °C. Marbofloxacin concentrations in plasma and tissues were analysed by means of high‐performance liquid chromatography using an ultraviolet detector. The limits of detection were 0.02 μg mL?1, 0.02 μg g?1, 0.025 μg g?1, 0.02 μg g?1 and 0.025 μg g?1 in plasma and muscle, skin, liver and kidney respectively. Fish were administered orally at a single dosage of 10 mg kg?1 body weight in the PK group. The data were fitted to two‐compartment open models at both temperatures. At 15 °C, the absorption half‐life () and distribution half‐life (t1/2α) of the drug were 0.36 and 4.48 h respectively. The corresponding values at 25 °C were 0.23 and 0.87 h respectively. The elimination half‐life (t1/2β) was 50.75 h at 15 °C and 25.05 h at 25 °C. The maximum MBF concentration (Cmax) differed little between 15 (6.43 μg mL?1) and 25 °C (8.36 μg mL?1). The time to peak concentration was 1.74 h at 15 °C and 0.78 h at 25 °C. The apparent volume of distribution (Vd/F) of MBF was estimated to be 1.36 and 0.87 L kg?1 at 15 and 25 °C respectively. The area under the concentration–time curve (AUC) was 301.80 μg mL?1 h at 15 °C and 182.80 μg mL?1 h at 25 °C. The total clearance of MBF was computed as 0.03 and 0.05 L h?1 kg?1 at 15 and 25 °C respectively. After repeated oral administration at a dosage of 10 mg kg?1 body weight per day for 3 days, the results showed that the elimination half‐lives () of MBF from all tissues at 15 °C were longer than that at 25 °C. Therefore, water temperature is an important factor to be considered when deciding a reasonable withdrawal time.  相似文献   

6.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.  相似文献   

7.
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   

8.
This study was conducted to determine the effects of hormone treatment on testis structure in Barbus sharpeyi, as well as the morphology of sperm examined by scanning electronic microscopy (SEM). Male B. sharpeyi were divided into three groups (three fish per group) and injected with luteinizing hormone – releasing hormone analogue (LHRH–A2) or carp pituitary extract (CPE). The first and second groups were treated with 10 μg kg?1 LHRH–A2 and metoclopramide (MET), and their testis were sampled pre‐ and Poststripping respectively. The third group received 2 mg kg?1 CPE and were killed pre‐stripping. Based on the histological results obtained, the testicular connective tissue of the lumen was thicker, and seminal vesicles were of a lower volume, in fish injected with CPE in comparison to the other groups. After treatment with LHRH–A2 and MET, not all spermatozoa within the testis were ejaculated, and only a small amount of sperm was obtained by abdominal stripping. The highest and lowest diameters of connective tissue within lobules were observed in fish receiving CPE and LHRH–A2 treatments respectively. There was a significant difference (P < 0.05) in lobule space between the fish injected with the CPE and the fish injected with the LHRH–A2 and MET. The SEM results revealed that the spermatozoa of B. sharpeyi were composed of a spherical to elliptical head, a cylindrical midpiece, and a lengthy flagellum. In conclusion, it was found that injection with LHRH–A2 and MET improved the spermatogenic process in comparison to injection with CPE.  相似文献   

9.
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   

10.
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   

11.
This study was aimed at quantifying methionine requirement of Indian major carp fry, Cirrhinus mrigala (2.2 ± 0.2 cm; 0.19 ± 0.02 g) by conducting a 12‐week feeding trial. Casein–gelatine‐based isonitrogenous (40 g 100 g?1 crude protein) and isoenergetic (15.42 kJ g?1 DE) amino acid test diets were prepared to contain six levels of l ‐methionine (1.1, 1.3, 1.5, 1.7, 1.9 and 2.1 g 100 g?1 dry diet) at a fixed level of cysteine (0.85 g 100 g?1 dry diet) and fed to apparent satiation thrice daily to triplicate groups of fish. When absolute weight gain (g per fish), feed conversion ratio, protein deposition (g per fish) and nitrogen retention efficiency data were subjected to broken‐line and second‐degree polynomial regression analysis, 95% of the plateau of above parameters was achieved at dietary methionine concentrations between 1.60 and 1.69 g 100 g?1 dry diet or 0.10 to 0.11 g methionine kJ?1 DE, corresponding to 4.1–4.22 g 100 g?1 protein or 0.44–0.47 g methionine kJ?1 DE. Based on these results, dietary methionine requirement of fry C. mrigala is recommended 1.60–1.69 g 100 g?1 diet or 0.10–0.11 g methionine kJ?1 DE.  相似文献   

12.
An 8 weeks feeding trial was conducted to determine the dietary methionine requirement of fingerling Indian catfish, Heteropneustes fossilis (6.08 ± 0.95 cm; 4.33 ± 0.52 g). Six isonitrogenous (40%) and isoenergetic (17.90 kJ g?1 GE) amino acid test diets were formulated with gradation of 0.25 g 100 g?1containing graded levels of L‐methionine (0.30, 0.55, 0.80, 1.05, 1.30 and 1.55 g 100 g?1, dry diet) with 0.40 g 100 g?1 constant level of cystine. Twenty fish were stocked in triplicate groups, in 75‐L circular trough with continuous flow‐through system and fed experimental diets at 4% BW/day twice daily, at 08:00 and 18:00 hours. Maximum live weight gain (296%), best feed conversion ratio (1.56) and protein efficiency ratio (1.60) were occurred at 1.05 g 100 g?1 methionine, beyond which they showed declining tendency. However, quadratic regression analysis of weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER) and body protein deposition (BPD) data indicated requirement for methionine at 1.15, 1.08, 1.06 and 1.05 g 100 g?1 of dry diet respectively. Significantly (P < 0.05), higher whole body protein content, minimum moisture and intermediate fat contents were recorded at 1.05 g 100 g?1 dietary methionine level. Ash content remained insignificantly (P > 0.05) low among all the treatments, excepting at diet I and diet II. Body protein deposition was also found to be significantly (P < 0.05) higher at 1.05 g 100 g?1 methionine level. Best somatic and haematological indices values were also obtained at the requirement level. Based on above results, it is recommended that the diet for young H. fossilis should contain methionine at 1.09 g 100 g?1 dry diet, corresponding to 2.73 g 100 g?1 dietary protein with 0.40 g 100 g1 cystine concentration for optimum growth and efficient feed utilization. Thus, the total sulphur amino acid requirement of H. fossilis would be (1.09 + 0.40) 1.49 g 100 g?1 of dry diet, corresponding to 3.73 g 100 g?1 of dietary protein.  相似文献   

13.
The effect of recombinant bovine placenta) lactogen (rbPL) treatment upon growth of juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum) (14.0 ± 0.31 g wet wt), was examined over a period of 6 weeks. Experimental animals were either injected (5 μg rbPL g?1 week?1), implanted with a cholesterol pellet containing 0.4 mg rbPL (approximately 4 μg g?1 week?1), or orally and rectally intubated with 7.5 μg rbPL g?1 week?1. Control animals were injected with bovine serum albumen (BSA), 5 μg g?1 week?1, implanted with a placebo or orally intubated (7.5 μg BSA g?1 week?1). Significant (P < 0.05) growth acceleration was recorded for rbPL-injected and pellet-implanted groups from week 2 onwards when compared against all other groups. Oral or rectal intubation of rbPL (7.5 μg rbPL g?1 week?1), however, was without effect. Condition factor decreased in all groups, but was significantly lower in rbPL-injected and pellet-implanted fish at trial end when compared against controls. No differences were recorded between groups for per cent body moisture or relative gut length. Hepatosomatic index was significantly (P < 0.05) higher in rbPL-injected and rbPL-implanted chinook salmon versus other fish.  相似文献   

14.
ABSTRACT

Mature female Indian catfish, Heteropneustes fossilis were induced to spawn in spawning season (July-August) by various ovulation-inducing agents, and the frequency of ovulation was checked after a latency of 12-14 hours of the treatment. Egg mass and fertilization rate were taken as end-points of spawning performance. [D-Ala6-Pro9] ethylamide GnRH analogue in dosages of 0.075, 0.15, 0.2, and 0.5 μg/g of body weight resulted in 28.5%, 71%, 86%, and 86% ovulation, respectively, but the lower doses of 0.01 and 0.05 μg/g body weight failed to induce ovulation in early spawning phase (July). The dopamine-2 (DA2) receptor antagonists pimozide, domperidone, and metoclopramide potentiated the anovulatory dose of 0.05 μ g GnRH analogue to induce ovulation in 86%, 86%, and 50% of the females, respectively, in the early spawning phase (July). The DA precursor, L-dihydroxyphenylalanine (L-DOPA; 10 μg/g body weight) and the DA agonist bromocriptine (10 μg/g body weight) decreased markedly the ovulatory response of 0.2 μ g GnRH analogue to 29%. The catechol-amine-synthesis inhibitor a-methylparatyrosine produced a mild depressing effect on the ovulatory response of 0.2 μ g GnRH analogue. Egg mass was high in groups that yielded a high ovulatory response (71% and above) except the a-MPT groups. The fertilization rate, however, was not affected, irrespective of the ovulatory response. The results show that the Indian catfish can be induced to spawn by superac-tive GnRH analogue alone in a dosage range of 0.15-0.2 μg/g body weight or in combination with DA2 antagonists, such as pimozide or domperidone, in a very low dosage of 0.05 μg/g.  相似文献   

15.
This study examined the pharmacokinetics and bioavailability of oxolinic acid (OA) in black tiger shrimp Penaeus monodon Fabricius, in brackish water (salinity 10 g L?1) at 28–29°C, after intra‐sinus (10 mg kg?1) and oral (50 mg kg?1) administration and also investigated the net changes of OA residues in the shrimp after cooking (boiling, baking and frying). The haemolymph concentrations of OA after intra‐sinus dosing were best described by a two‐compartment open model. The distribution and elimination half‐lives were 0.84 and 17.7 h respectively. The apparent volume of distribution at a steady state and the total body clearance were estimated to be 2061 mL kg?1 and 90.1 mL kg?1 h?1 respectively. The bioavailability of OA after an oral administration was 7.9%. The peak haemolymph concentration, the time to peak haemolymph concentration and the elimination half‐life after oral administration were 4.20 μg mL?1, 4 h and 19.8 h respectively. Oxolinic acid muscle and shell levels increased to a maximum (muscle 1.76 μg g?1 and shell 8.17 μg g?1) at 4 h post administration and then decreased with the elimination half‐life value of 20.2 and 21.9 h respectively. Residual OA in muscle and shell was reduced by 20–30% by each cooking procedure examined.  相似文献   

16.
汪小东 《水产学报》2000,24(2):123-129
雄鳗注射５－６次、雌鳗注射９－１０次鲤脑体匀浆液（ＣＰＥ）＋人绒毛膜促性腺激素（ＨＣＧ）能分别诱导精巢和卵巢发育成熟。在雌雄鳗鲡,注射ＣＰＥ＋ＨＣＧ可显著增加端脑、间脑、中脑和下丘脑ｍＧｎＲＨ的含量,而对后脑和延髓ｍＧｎＲＨ的影响较小;注射ＣＰＥ＋ＨＣＧ增加雄鳗后脑和延髓ｃＧｎＲＨ－Ⅱ含量,对雌鳗脑区ｃＧｎＲＨ－Ⅱ则无显著影响。雌雄鳗鲡每次注射ＣＰＥ＋ＨＣＧ后１天,血清促性腺激素（ＧｔＨ）急剧上升  相似文献   

17.
SLICE? (active ingredient 0.2% emamectin benzoate (EMB)), a feed premix developed by Schering‐Plough Animal Health for the control of sea lice on cultured salmonids, is registered for use in several countries and is being prescribed on an emergency basis in Canada and the United States. The concentration of EMB in feed administered to farmed salmon ranges from 1 to 25 μg g?1. To determine the acute toxicity of the compound to juvenile and adult American lobster (Homarus americanus), commercial salmon feed was coated with SLICE? at a range of concentrations and provided to the animals for 7 d in the laboratory. The LC50 is estimated to be 644 μg g?1 (95% CI=428, 1275) for adult lobsters and >589 μg g?1 for stage V and VI juvenile lobsters. The consumption of medicated pellets by adult lobsters decreased significantly with increasing concentration of EMB. Adult lobsters that died during the study had a significantly greater concentration of emamectin B1a in their muscle tissue than those that survived. These results support the conclusion that salmon feed medicated with EMB at the concentrations used by the aquaculture industry is unlikely to pose an acute lethal threat to adult and small juvenile American lobsters.  相似文献   

18.
The action of neuropeptide Y (NPY) and gonadotropin releasing hormone (s-GnRH) have been compared on the release of gonadotropin (GtH) by perifused rainbow trout pituitary glands sampled from freshly ovulated female rainbow trout. We have already demonstrated that NPY stimulated the secretion of GtH in vitro. The pituitary responses to s-GnRH and NPY were similar either after repeated 10 min infusions or a one hour prolonged application. In both cases, after the first application, the pituitary did not responded to subsequent secretagogues stimulations, and appeared to be desensitized. The stimulatory action of s-GnRH was partly inhibited (60%) by LH-RH antagonist (DpGlu1, DPhe2, DTrp3–6) LH-RH, which completely inhibited the response to NPY in perifused pituitary glands sampled from freshly ovulated females, but did not modify the response of pituitaries taken from vitellogenic animals in which NPY induced a transient inhibition of the GtH secretion. These results may indicate that the mode of action of NPY would differ between vitellogenic and matured animals. NPY also stimulated the GtH secretion from perifused pituitary dispersed cells prepared from pituitaries taken from freshly ovulated rainbow trout, indicating that NPY may act directly on the pituitary gonadotropic cells to stimulate GtH secretion.  相似文献   

19.
A grow‐out experiment was designed to determine the effect of different dietary protein, lipid levels and protein–energy (P:E) ratio on growth performance and feed utilization of the freshwater prawn, Macrobrachium rosenbergii post larvae (PL) culture in pond net enclosures (hapa, 3.75 m?3 each) for 12 weeks (84 days). The experimental treatments were assigned in triplicate. Six test diets were formulated to contain three different protein levels (300, 350 and 400 g kg?1 diet) and two lipid levels (100 and 140 g kg?1 diet) in a factorial manner (3 × 2) to provided six different dietary P:E ratio: 16, 17, 18, 19, 20 and 21 mg CP kJ?1 g?1). The result showed that the highest significant (P≤0.05) survival rate, growth indices and feed utilization were observed for M. rosenbergii PL fed a diet with a P:E ratio of 17 mg CP kJ?1 g1, whereas, the lowest value was recorded for prawns fed a diet with a P:E ratio of 20 mg CP kJ?1 g?1. Whole body contents of protein and lipid were highest (P≤0.05) when fed diets with 21 and 17 mg CP kJ?1 g?1 respectively. Concerning dietary protein levels, the highest (P≤0.05) values for survival and growth indices were observed for PL fed a diet containing 300 g kg?1 diet protein. The same trend was observed for PL fed a diet with 100 g kg?1 diet lipid level, irrespective of dietary protein levels. A diet containing 300 g kg?1 protein and 100 g kg?1 lipid with a dietary P:E ratio of 17 mg CP kJ g?1 is recommended to stimulate growth performance and nutrients utilization efficiency of M. rosenbergii PL.  相似文献   

20.
Indian major carp fingerling, Cirrhinus mrigala (3.85±0.75 cm, 0.52±0.21 g), were fed isonitrogenous and isocaloric diets (40% crude protein, 4.28 kcal g?1, gross energy) containing casein, gelatin and crystalline amino acids with graded levels of l ‐threonine (1.00, 1.25, 1.50, 1.75, 2.00 and 2.25 g 100 g?1, dry diet) to determine the dietary threonine requirement. The feeding trial was conducted in triplicate for 8 weeks. Diets were fed twice a day at 08:00 and 16:00 hours at 5% body weight day?1. The ration size and feeding schedule were worked out before the start of the feeding trial. Highest weight gain (304%) and best feed conversion ratio (1.43) were evident in fish fed diet containing 1.75% dietary threonine. Second‐degree polynomial regression analysis of weight gain, feed conversion ratio and protein efficiency ratio data indicated the dietary threonine requirement to be at 1.84%, 1.81% and 1.78%, respectively, corresponding to 4.60%, 4.52% and 4.45% of dietary protein. Minimum carcass moisture, fat and maximum carcass protein were evident in fish fed 1.75% threonine level. However, ash content did not affect body composition, except the 1.00% threonine level, which showed a significantly higher ash content value. Based on the above results, it is recommended that the diet for C. mrigala should contain threonine at 1.80 g 100 g?1 dry diet, corresponding to 4.50 g 100 g?1 dietary protein for optimum growth and efficient feed utilization.  相似文献   

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