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1.
Triploidy was induced in mud loach (Misgurnus mizolepis) by cold shocking fertilized eggs 5 min post-fertilization at 2°C for 15 to 60 min. Best results were obtained when eggs were shocked for 60 min; 98% of fish examined in that treatment were triploids. Triploidy was confirmed by erythrocyte measurements and chromosome counts. Diploids had 48 chromosomes, while triploids had 72. Histological analysis of 9-month-old triploid ovaries showed an appreciable number of oocytes at the chromatin nucleolus stage with considerable interstitial tissue. However, diploids had well developed oocytes. Diploid testes from diploid males exhibited normal spermatids and spermatozoa, while a few were seen in triploid males. Growth rate was evaluated over a 9-month growth trial. Although male and female triploids were slightly heavier than their diploid counterparts from the third to the ninth month, their growth rates were not significantly different compared to their diploid controls.  相似文献   

2.
Production of sterile triploid red tilapia [Oreochromis mossambicus (Mozambique tilapia); Peters, 1852 × Oreochromis niloticus (Nile tilapia); Linnaeus, 1758] is an effective strategy to overcome their prolific breeding. Optimal conditions for cold-shock induction of triploidy in red tilapia were investigated by experimentally examining two variables: appropriate temperature of the shock and duration of shock treatment. A constant time after insemination of 4 min was used to determine the best combination of temperature (6, 7, 8, 9, 11, 13, 15 °C) with different durations of shock (10, 20, 30, 40, 50 min) with resultant ploidy level verified karyotypically. Shock duration for 30 min at a temperature of 9 °C was found most effective in producing maximum triploidy (98.7 %) with higher rates of hatching (63.2 %) and survival up to yolk-sac stage (75.8 %). The chromosome count confirmed that triploid percentages were higher when cold shock was used for longer durations at each temperature; however, hatching rates were generally decreased. The maximum triploid yield (82.1 %) obtained was higher than the yield obtained using heat shock (72.7 %) in red tilapia previously. The application of the results of this study has the potential to greatly improve the production of triploid red tilapia in commercial aquaculture.  相似文献   

3.
Abstract.— Induction of triploidy and tetraploidy in Nile tilapia, Oreochromis niloticus , was investigated by heat shock, cold shock, hydrostatic pressure, and/or chemicals (cytochalasin A, B, and D). Additionally, efficacy of combined protocols was determined. Heat shock 10 min after fertilization induced triploidy when incubation temperature was 24 C but not when incubation temperature was 31 C. Heat shock of 40–41 C at 4–6 min after fertilization was effective in inducing up to 100% triploidy with hatchability similar to controls. Cold shock at 13 C for 45 min five min after fertilization induced 85–100% triploids. Heat shock and multiple heat shocking were the most effective treatments for the induction of tetraploidy. Two heat treatments of 41 C applied at 65 and 80 min after fertilization for 5 min each produced approximately 80% tetraploidy in hatched fry. Immersion of fertilized eggs in cytochalasin A, B, or D at concentrations up to 10 μg/L applied at various times and durations was ineffective in inducing triploidy or tetraploidy.  相似文献   

4.
Induction of triploidy and tetraploidy was attempted in Heteropneustes fossilis using heat shock. The optimal age of zygote, temperature level and duration of thermal shock required for effective induction of triploidy and tetraploidy was investigated in a series of experiments. A maximum of 82±7% triploids (3n=87) were obtained when fertilized eggs (2.5‐min old) were heat shocked at 40°C for 4‐min duration. A maximum of 40±8% tetraploids (4n=116) was obtained when the fertilized eggs (30‐min old) were heat shocked at 40°C for 4‐min duration. The triploid and tetraploid red blood cells (RBCs) nucleus volumes were 1.4 and 2.1 times greater, respectively, than that of the diploid RBC nucleus.  相似文献   

5.
In a 2-year grow-out trial, triploid Sydney rock oysters, Saccostrea commercialis (Iredale & Roughley), from two initial size grades grew faster (in terms of both mean whole weight and shell height) than the equivalent initial size grades of sibling diploids (P < 0.05). Small size grade triploids caught up with and had significantly heavier (P < 0.05) final whole weights than large size grade diploids after a 2-years grow-out period. The initial size grade had a significant effect on final mean whole weight and shell height for both ploidy types. After the 2-years grow-out trial, the final mean whole weights (but not shell heights) of small and large diploids (35.8 ± 0.6 g and 39.4 ± 0.5 g, respectively) were significantly different (P < 0.05). Small and large triploids grew at a similar rate for the first 18 months despite the significantly (P < 0.05) heavier final mean weight of large grade triploids (48.4 ± 0.8 g and 61.2 ± 0.7 g, respectively). The effect of the initial size grade on subsequent growth of both diploid and triploid oysters which was demonstrated in the present study is of significant commercial value to hatchery and nursery operators as well as growers of single seed oysters. In addition, small-grade triploids appeared to be more valuable in terms of potential growth rate than all diploid grades. There was no significant difference in the final percentage triploidy between small and large grade triploids. A large proportion of diploid/triploid mosaicism was detected in adult oysters.  相似文献   

6.
Triploidization is an interesting tool to produce sterile fish. In the yellowtail tetra, Astyanax altiparanae, this can be applied for aquaculture and surrogate technologies. In this study, we compared the efficacy of cold (2 C) or heat shock (38 C, 40 C, and 42 C) on triploid induction in the yellowtail tetra. The eggs were treated with cold or heat shock, 2 min postfertilization (30 min in cold shock or 2 min in heat shock). Intact embryos served as the control group. Ploidy status was confirmed by karyotyping, flow cytometry, and nuclear diameter of erythrocytes. The hatching rate decreased after cold shock (12.69 ± 15.76%) and heat shock at 42 C (0.35 ± 0.69%) in comparison with the control group (63.19 ± 16.82%). At 38 C and 40 C, hatching rates (61.29 ± 17.73% and 61.75 ± 22.1%, respectively) were not decreased. Only one triploid arose at 38 C (1/80). At 40 C, a high number of triploids arose (72/78). At 42 C, very few embryos developed into the hatching stage. A large number of haploid individuals arose after cold shock (61/75), with only one triploid. Our results indicate that heat shocking of embryos at 40 C is optimum for triploid production in the yellowtail tetra.  相似文献   

7.
Triploidy as a result of thermal shock exposure of fertilized eggs decreases the growth rate ofOreochromis aureus as compared to their diploid controls, but this is due to the higher female ratio present in triploids (86%) and the lower growth rate of females. When females and males are considered separately, the growth rate is not significantly different in diploids and triploids. Since triploidy results in a malfunctioning steroidogenesis in females (mainly testosterone (T) and 17β-estradiol (E2)), but does not affect the growth rate, it is concluded that female gonadal steroids do not influence growth unless in pharmacological concentrations. These low levels of gonadal steroids are generally accompanied by higher levels of gonadotropin (GtH), but the difference is not always significant. Despite their lower growth rate diploid females have higher plasma concentrations of growth hormone (GH) during several months compared to the triploid females and diploid males. 3,5,3′-triiodo-L-thyronine (T3) levels, however, are comparable between diploid and triploid females (except for 1 month), but higher in diploid males in 4 of the 5 months studied. 11-ketotestosterone (11kT) is always higher in males. These results indicate that the higher growth rate of males may be related to the high circulating levels of T3 and 11kT.  相似文献   

8.
Abstract. Triploidy was induced in the fighting fish, Betta splendens Regan, by varying all possible combinations of temperature (37-41°C), time after insemination (2-3min)and shock duration (2-4 min). Heat shock at 39°C for 3 min duration initiated 2-5 min after insemination gave high frequencies of triploids (86%) as assessed from chromosome number and red blood cell nuclear volume. There was no significant difference in the growth rate of triploid and diploid fish. Gonadal development in both sexes was retarded in triploids at 5 months of age. Eggs fertilized with milt from triploids developed to gastrulation. Beyond gastrulation there was increasing mortality associated with abnormalities and none of them hatched. The display frequencies of air gulping, erection of operculum and fins, striking and biting, and undulating movements were fewer in triploids compared to diploids. It appears that triploids are less aggressive than diploids. The aggressive behaviour of fighting fish may be related Io their reproductive activity.  相似文献   

9.
The tench Tinca tinca is an interesting fish from the viewpoint of polyploidy and related atypical reproduction aspects. Triploid tench were produced artificially. Studies of spermiation as well as of sperm motility and structure were performed on several triploid and diploid males simultaneously with individual experimental crosses with diploid females to define their reproductive capacities. The testes of triploids visually looked less developed in the most of cases with lower sperm production (0.05 cm3 sperm per male), GSI and weight of testes compared to diploids (0.58 cm3 sperm per male). Analysis of variance showed significant influence of ploidy level on the percentage of motile spermatozoa. Triploidy did not change percentage of live spermatozoa and velocity of spermatozoa at the first time of sperm movement. The study of sperm structure by scanning electron microscopy revealed that most sperm cells were of normal structure with some anomalies. Sperm heads of triploid and diploid males were mostly round-shaped, 1.86±0.2 and 1.6±0.18 μm in diameter. The midpiece of triploid spermatozoa was slightly narrower than that of diploid ones with typical cylindrical shape. Flow cytometry revealed sperm cells of triploids to be largely aneuploid (1.47 n) with high mosaic DNA, oscillating from haploid DNA content (1.0 n) to diploid DNA content (1.9 n). Experimental crosses between triploid males and diploid females revealed that these males were capable to stimulate effective development with relatively high level of fertilization and hatching rates from 0 to 70%. In conclusion, triploidization does not seem to guarantee sterility of tench.  相似文献   

10.
A comparison of composition and sensory evaluation were performed on fillets of Oreochromis niloticus (wild type) and red hybrid tilapia (RHT) (Florida red tilapia ♂× red O. niloticus♀). Fifty male tilapia, 25 O. niloticus (initial weight 159.3 g) and 25 red hybrid (initial weight 132.4 g), were placed in each of three 2.0 m3 volume tanks. The fish were fed a commercial feed containing 35.9% crude protein during the 120‐day experimental period and then killed in cold water (3°C). All the fish were filleted. Twelve fillets from each treatment were used for proximate analyses, five fillets from each treatment were used for fatty acids analyses and the remaining fillets were used for sensory evaluation. The compositional analyses showed similar moisture, true protein and ash content in both genetic groups, but a lower crude fat content was measured in the red hybrid fillets (0.70%) compared with that of O. niloticus fillets (0.97%). No differences between O. niloticus and the red hybrid were observed in their fillet profile of fatty acids. In the sensory evaluation test, a difference in fillet flavour between both genetic groups was perceived. Of the 112 consumers in the preference test, 81.2% perceived a difference in fillet flavour between the two tilapias, with a general preference for the red hybrid over the wild‐type O. niloticus. The benefits of cultivating a RHT with a low lipid content are discussed.  相似文献   

11.
Triploid hybrid saugeyes may be a desirable stocking alternative because diploid saugeyes are fertile and can compromise the genetic integrity of parental stocks. Four groups of saugeye eggs were heat-shocked 5 min after fertilization for 15 min at 31 °C, which resulted in an 86.7 ± 9.4% triploidy rate and 57.8 ± 24.3% survival to the eyed-stage. Heat shocked and control saugeyes were stocked in two ponds for 40 days at 395 000 ind. ha–1. Mean length and weight of triploid and heat-shocked diploid saugeyes were greater ( P  < 0.01) than unshocked diploid saugeyes. Survival of heat-shocked saugeyes (22.4%) was lower than unshocked saugeyes (94.7%). Heat-shocked fish ( n =25 851) harvested from ponds were stocked for 153 days in O'Shaughnessy Reservoir, Ohio, USA. Triploids were 34 mm shorter and weighed 41 g less than heat-shocked diploids ( P  < 0.01). Mean length and weight of triploids were comparable with unshocked diploids elsewhere in Ohio.  相似文献   

12.
A 10‐week feeding trial was conducted to investigate the interaction between tilapia genotype and dietary protein level on the growth, feed utilization efficiency and body composition of Nile tilapia [Oreochromis niloticus L., F9 generation of genetically improved farmed tilapia (GIFT) strain] and red hybrid tilapia (Oreochromis sp.). Two isoenergetic diets (15.5 kJ g−1 diet) containing 25% or 35% crude protein were formulated and fed to triplicate groups of tilapia (12.8±0.2 g) at a fixed daily ration of 4% of their body weight. The growth performance of the GIFT tilapia fed 25% or 35% dietary protein was significantly higher (P<0.05) compared with red tilapia at either protein level. Increasing the dietary protein level by 10% led to a further 10% increase in the final weight of GIFT tilapia but no further increase was observed in the weight gain of red tilapia. Growth was influenced by the interaction between diet and tilapia genotype. Feed conversion ratios were 14% and 33% better in GIFT tilapia compared with red tilapia fed the 25% or 35% protein diet respectively. Protein efficiency ratio and net protein utilization were influenced by both diet and tilapia genotype, but not the interaction between the two. The apparent digestibility coefficients of dry matter and protein did not differ significantly between the two diets and tilapia genotypes but lipid digestibility was 1.2–4.7% higher for the GIFT tilapia. Tilapia whole‐body protein content was significantly influenced by both diet and tilapia genotype. The higher growth potential, better feed utilization efficiency and higher body protein content of GIFT tilapia compared with red tilapia should have a positive impact on tilapia farming in terms of production costs.  相似文献   

13.
The precociously sexual maturation in large yellow crocker Pseudosciaena crocea has become a serious problem. In an attempt to solve this problem, the production of sterile triploids could be an effective strategy. In this study, triploid P. crocea was obtained by subjecting fertilized eggs to pressure shock. Flow‐cytometry analysis was used to assess ploidy level. In terms of triploid rate and hatching rate, the optimal conditions of pressure shock for triploidy induction in P. crocea were 7500 psi for 3 min shock at 3 min after fertilization at 20 °C. With the application of these parameters, 100% triploid fish were produced. During the first rearing year, triploid P. crocea had a similar growth performance compared with its diploid counterpart before the age of 8 months and showed a significant advantage at the age of 10 and 12 months in body weight and body length (P<0.05). At the age of 12 months, the carcass weight of triploids was markedly higher than that of diploid control, and gonadal somatic index was significantly lower than that of their diploid control. During the first rearing year, survival in triploid group was 76.44%, inferior to its diploid control (83.21%).  相似文献   

14.
The objective of this study was to evaluate the effects of fishmeal (FM) replacement with corn protein concentrate (CPC) on growth performance, nutrient utilization, gut morphology and skin coloration of red hybrid tilapia, Oreochromis sp. Five isonitrogenous (350 g/kg crude protein) and isolipidic (10 g/kg lipid) diets were formulated to contain CPC that substituted 0%, 25%, 50%, 75% or 100% FM. Diets were fed to triplicate groups of tilapia (mean initial weight, 10.33 ± 0.02 g) twice daily for 63 days. The results showed that replacing up to 50% FM in red hybrid tilapia diet with CPC did not show any significant adverse effects on growth, feed utilization, haematocrit counts, condition factor and gut morphology of tilapia (p > 0.05). However, replacing 75% or 100% FM with CPC had deleterious effects (p < 0.05). Carotenoids in CPC contributed to skin yellowness, which was significantly higher in the diet where 100% FM was replaced with CPC. Using regression analysis, the optimal substitution level of FM by CPC was estimated at 25% for percentage weight gain, 33% for FCR and 29% for protein efficiency ratio. CPC could be used as a single plant protein source to substitute up to 50% FM in red hybrid tilapia diets.  相似文献   

15.
Tilapia (Oreochromis, spp.) have been introduced globally and domesticated, resulting in a number of different strains. This diversity offers the potential for difference in body morphology and, in turn, fillet yields. A trial was conducted at Auburn University, Auburn, Alabama, to compare processing characteristics of four populations of Oreochromis niloticus using two domesticated strains (Egypt and Ivory Coast), two less domesticated strains (Sagana and Lake Victoria), and a red variety (Santa Fe). Male tilapia (N?=?25/strain) were manually processed and the dress-out percentage and visceral fat calculated. Mean individual weights of pre-processed fish were similar (range = 403.8 ± 27.6 g to 413.8 ± 24.5 g) with the exception of the larger Sagana strain (434.2 ± 15.4 g). The Ivory Coast strain had the highest percent dress out (33.1% ± 2.1%), while the Sagana strain had the lowest (29.6% ± 1.5%). The Red strain had the greatest percent visceral fat (2.3% ± 1.0%) and the Sagana had the lowest (0.2% ± 0.4%).  相似文献   

16.
Growth performance, survival and feed utilization of diploid (2n) and triploid (3n) sex‐reversed male and female Nile tilapia were evaluated at maintenance feeding (1% body weight (BW) day?1), fixed feeding (3% BW day?1) and apparent satiation feeding levels in a freshwater recirculation system comprised of thirty‐six 1‐m3 concrete tanks at the Asian Institute of Technology, Bangkok, Thailand. Triploid Nile tilapia (3n) was produced by subjecting fertilized diploid (2n) tilapia eggs to heat shock. After hatching, fish were sex‐reversed to all‐male and all‐female populations by oral administration of 17 α‐methyltestosterone (60 mg kg?1 feed) and ethynylestradiol (100 mg kg?1 feed) respectively. There was significantly higher growth with increased ration levels in both male and female groups. There were no significant differences in final BW, specific growth rate, survival rate, feed conversion ratio and protein efficiency ratio between diploid and triploid fish. Triploids had lower gonad weights than diploids, and this was particularly evident at the satiation feeding level. Triploid fish had a significantly higher apparent net protein utilization and percentage of gutted weight than diploids at all feeding levels. Higher protein utilization efficiency of triploids might be an advantage for commercial tilapia culture but further research is necessary to make such a conclusion.  相似文献   

17.
Growth and feed conversion were monitored in triplicate groups of the African catfish Heterobranchus longifilis (mean weight 11 ± 1.8 g) fed small (2.5–5.54 cm) tilapia (Oreochromis niloticus) and artificial feeds at various rates (treatments 1, 2, and 3), and tilapia or artificial feed (treatments 4 and 5, respectively). Artificial feed was a 42% crude protein commercial pellet. Live O. niloticus were fed at a rate of 4 g live tilapia/catfish/day. Pelleted feeding rate was 2%, 1%, 0.5%, and 1% of body weight thrice daily in treatments 1, 2, 3, and 5, respectively. After 70 days, mean weight was 180 ± 9.5 g, 157 ± 15.7 g, 147 ± 2.6 g, 77 ± 10.9 g, and 74 ± 10 g, in treatments 1, 2, 3, 4, and 5, respectively. Treatment significantly affected SGR (% day?1) (P < 0.03) and pelleted feed conversion ratio (P < 0.0003). FCR was 1.09 ± 0.01, 0.63 ± 0.08, 0.42 ± 0.11, and 1.12 ± 0.13 in treatments 1, 2, 3, and 5, respectively. Profit was highest (P < 0.01) in treatment 2. Tilapia consumption seems to improve utilization of artificial feed and may be a way for some catfish farmers to save money.  相似文献   

18.
Induction of triploidy has been suggested as an effective tool to prevent spawning of farmed fish. This experiment examined the growth potential of triploid cod when reared communally with diploid ones after the juvenile stage. Pressure treatment was used to induce triploidy in a batch of cod eggs in April 2009. The resulting offspring were reared separately from their diploid counterparts until they reached the proper size for PIT tagging. At the age of 8 months, an equal number of 115 diploids (135.5 ± 3.95 g) and triploids (93.6 ± 2.63 g) were communally reared in a circular flow-through tank until the age of 22 months. By the end of this rearing period, diploids (1,002.4 ± 39.9 g) were significantly heavier than triploids (654.6 ± 27.7 g), but the specific growth rate did not differ significantly during the growth trial. Gonadal development at the age of 22 months was also lower among triploids than diploids, especially for females (5.3 and 91.9 %) but also for males (32.5 and 72.7 %). Sterility among female triploids was evident by the reduced size and dysfunctional gonads, but gonadal development in male triploids was less suppressed. Prevalence of body deformities was, however, significantly higher among triploids (62.6 %) than diploids (33.9 %). Higher prevalence of deformities in triploid cod underlines the need for further fine-tuning of the triploidization procedure or finding other methods of sterilization. At present, triploid cod are still far from being established as an alternative for commercial production.  相似文献   

19.
Abstract

The viability of mixed-feeding schedules utilizing low-and high-protein diets for the production of monosex hybrid red tilapia, Oreochromis mossambicus × O. niloticuswas evaluated. Male red tilapia juveniles (mean initial weight 16.8±0.08 g) stocked at a rate of 159 fish/m3 in canvas tanks (3.05m × 0.92m × 1.22m) were grown under five different feeding schedules for 24 weeks. Two schedules, using low (25%, A) and high (35%, B) dietary protein were designated as control. Three mixed-feeding schedules tested were: the feeding of 1 day of low protein diet followed by 3 days of high-protein diet (1A/3B); 2 days of low-protein diet followed by 3 days of high-protein diet (2A/3B); and 3 days of low-protein diet followed by 3 days of high-protein diet (3A/ 3B). Results showed that growth performance parameters, such as specific growth rate (% SGR), percent gain, and weight gain were significantly higher (P < 0.05) for fish maintained on the feeding schedule of 3A/3B. Similarly, the feed conversion ratio, protein efficiency ratio, and protein retention values were also significantly better for fish grown under this schedule. In terms of production, the 3A/3B feeding schedule also resulted in the highest total yield (kg/m3) and yield above 250 g. The 3A/3B feeding schedule resulted in a 10.1% protein saving relative to Diet B. These results suggest that a 3A/3B feeding schedule be adopted for the best biological and economical performance of red tilapia.  相似文献   

20.
A comparison was made of some productive traits of Stirling Nile tilapia (wild type) (Oreochromis niloticus, Linnaeus) and red hybrid tilapia (Florida red tilapia× Stirling red O. niloticus) males during a 98‐day grow‐out period. Twenty‐two males from each genetic group with initial weights of 139.0 g for O. niloticus and 207.3 g for the red hybrid were placed in triplicate tanks. The fish were fed with a feed containing 36.8% crude protein. Survival was 97.0% for the red hybrid and 83.3% for O. niloticus. Daily individual weight gains were 2.95 and 2.50 g and final body weights were 473.0 and 348.8 g for the red hybrid and O. niloticus respectively. Fillet yield was similar for both the species, with 33.4% for the red hybrid and 32.0% for O. niloticus. Fresh fillet lipid content was perceptibly less in the red hybrid (0.33%) than in O. niloticus (2.07%). Some benefits of a red low‐fat tilapia genotype are discussed.  相似文献   

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