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Avaliação das características seminais e criopreservação do sêmen de Pseudoplatystoma corruscans (Siluriforme pimelodidae) /Velarde, Johanna Maritza Cano. January 2013 (has links)
Orientador: Alexandre Ninhaus Silveira / Banca: Danilo Pedro Streit Júnior / Banca: José Augusto Senhorini / Resumo: O pintado Pseudoplatystoma corruscans é uma espécie com ampla distribuição na América do Sul e de grande valor comercial. P. corruscans necessita migrar para reproduzir e, atualmente, apresenta seus estoques comprometidos devido às alterações dos rios, construção de barragens e pela sobre-pesca. Os objetivos são analisar as características espermáticas e desenvolver um método de congelamento para o sêmen de P. corruscans. Para isso, catorze machos maduros de pintado foram selecionados e induzidos hormonalmente à espermiação. Foram avaliadas as características seminais do sêmen fresco (cor, concentração espermática, motilidade subjetiva). Para o sêmen descongelado foi utilizado o sistema CASA (Computer Assisted Sperm Analisis), onde se fez a verificação da motilidade seminal. Para o desenvolvimento dos protocolos de criopreservação, utilizou-se uma solução diluidora composta de glucose (5,0g), gema de ovo (10%), crioprotetor (DMSO e DMA a 8% e 10%) e água destilada (a.d.q.s). O material espermático foi coletado em dois locais, na Estação de Hidrobiologia e Aquicultura da Usina Hidroelétrica de Jupiá, Castilho, SP, onde as análises do sêmen fresco apresentaram sêmen de cor branco, muito diluído com pouca viscosidade e um volume seminal 4,6±1,5 (mL); a motilidade total espermática média foi de 92,3±9,7%; a concentração espermática média de 85,7 x 10 6 ± 35,49 sptz/mL; e um tempo de ativação de 35 segundos. O material espermático coletado no CEPTA-ICMBIO apresentou uma cor branca com alta viscosidade e um volume seminal de 7±2,3 (mL); foi encontrada uma concentração espermática média de 111,458 x 10 6 ±6,71 espermatozoides/mL; uma motilidade total espermática média de 92,4±5,2%; e um tempo médio de ativação de 32,33±4,0 segundos. As análises da motilidade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: he pintado Pseudoplatystoma corruscans is a species with wide distribution in South America and of great commercial value. P. corruscans need to migrate to reproduce, and currently has compromised their inventories due to changes in rivers, dams and overfishing. The goal, analyze the sperm characteristics and develop a method for freezing semen of P. corruscans. For this, fourteen of mature males were selected and painted to hormonally induced spermiation. We evaluated the seminal characteristics of fresh semen (color, sperm concentration, motility subjective). The thawed semen was used CASA system (Computer Assisted Sperm Analysis), where he made the seminal verification motility. For the development of cryopreservation protocols, we used a diluting solution consisting of glucose (5.0 g), egg yolk (10%), cryoprotectant (DMSO and DMA 8% and 10%) and distilled water (adqs). Spermatic material was collected at two sites in Hydrobiology and Aquaculture Station Hydroeletric Jupiá, Castilho, BC, where the fresh semen analysis showed semen color white, diluted with very little viscosity and a seminal volume 4.6 ± 1.5 (ml), sperm motility overall average was 92.3 ± 9.7%, the average sperm concentration of 85.7 ± 35.49 x 106 SPTZ / mL, and an activation time of 35 seconds. The material collected in the spermatic CEPTA-ICMBIO had a white color and light brown with high viscosity and a seminal volume of 7 ± 2.3 (ml), sperm concentration was found an average of 111.458 ± 6.71 x 106 sperm / mL; one sperm motility overall average of 92.4 ± 5.2%, and an average time of activation of 32.33 ± 4.0 seconds. Analysis of the motility after thawing showed a decrease in sperm motility by prior activation due to high level of urine in fish. And when you compare the two treatments with cryoprotectants DMSO and DMA were no... (Complete abstract click electronic access below) / Mestre
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Biology and stock assessment of the coastal fish, Sarpa Salpa (Sparidae), off the KwaZulu-Natal coast, South Africa.Van Der Walt, Bryan Anthony. January 1995 (has links)
This study investigated aspects of the biology of Sarpa salpa,
such as reproduction, age and growth, and mortality, which are
necessary for an assessment of the status of this species off the
KwaZulu-Natal (KZN) Coast.
The importance of S. salpa to the shore-based fishery in KZN was
evaluated using Natal Parks Board shore patrol data. These data
were validated by analysing preliminary results of an independent
shore-angling survey along the KZN Coast. Despite differences
in the catch composition and catch rates between the two
analyses, both data sources highlighted the importance of S.
salpa to the shore-based fishery in KZN. Shore-based catches
were markedly seasonal coinciding with the breeding season of the
species. The species in KZN is targeted primarily to provide a
supplementary source of animal protein.
An investigation of the reproductive biology of S. salpa
indicated a protracted spawning period for the species. Size at
50 percent maturity for combined sexes was attained at 145 mm
fork length. The sex ratio in shore-based catches was 1:1.6 in
favour of males. A frequency distribution by size indicated that
males dominated the smaller size classes while females dominated
the larger size classes. Detailed histological examination of
gonadal development showed that S. salpa has the potential for
protandrous sex change.
An age and growth study based on the examination of whole
otoliths indicated that S. salpa was relatively fast-growing and
a maximum age of six years was recorded for the species. One
opaque band was laid down per year. This was validated by
marginal increment analysis and by an oxytetracycline labelling
experiment using captive fish. Growth in S. salpa was described
by a Von Bertalanffy growth function:
Lage (mm FL) = 224mm(1 -e-o.55 year-1(age+o.51years))
The natural mortality rate (M = 0.6 year-1) was derived using
Pauly's equation and the current fishing mortality (F) rate was
estimated at 0.8 year-1. The current status of S. salpa in the
shore-based fishery was assessed by determining the effects of
F and age-at-capture on the yield- and spawner biomass-per-recruit.
Current levels of fishing pressure on S. salpa appeared
to be appropriate for utilisation of the stock off the KZN South
Coast. In terms of management, S. salpa appears to be in no need
of any restrictive measures at present. / Thesis (M.Sc.)-University of Natal, Durban, 1995.
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Aspects of the reproductive biology and endocrinology of the substrate-spawning cichlid Tilapia zilliiCoward, Kevin January 1997 (has links)
This study investigated several, previously little-known, aspects of reproductive physiology and endocrinology in the substrate-spawning cÌchlid Tilapia zillii; a tilapia that is becoming increasingly popular in world aquaculture. Studies were undertaken in controlled laboratory aquaria, thereby reducing the potential influence of environmental variation evident in many previous field studies of this species. Analysis involved two strains of T. zillii: strain 'A' (T. zillii) and strain 'B' (formerly known as Tilapia tholloni). Spawning periodicity and total fecundity generally increased with fish size. Egg size varied within a narrow window and did not generally increase with fish size though fish weighing 100 - 200g tended to produce the largest eggs. The best estimate of spawning periodicity was considered to be 'mean days elapsed/spawn' as this figure was based upon both spawning and non-spawning fish in an experimental group. Mean days elapsed/spawn increased with increasing fish size and averaged 61.4 days and 37.5 days in strains 'A' and 'B' respectively. The shortest reproductive cycles observed were just 7 days and 6 days for strains 'A' and 'B' respectively. Total fecundity ranged from 461 - 11640 eggs/clutch. Mean total fecundity was 3606+/-280 in strain 'A' and 3560+/-243 in strain 'B'. Mean egg diameter was 1.5+/-0.04mm and 1.4+/-0.08mm in strains 'A' and 'B' respectively. Fecundity and egg size also varied over successive spawns in serial-spawning females but these variations did not appear to be related to spawning periodicity. Regression analysis revealed strong relationships between fish size (weight and length) and total fecundity, relative fecundity and total egg volume. Relationships between fish size and egg size were generally much weaker. Fecundity and egg size were related to the length of the preceding inter-spawn-interval (ISI) in fish of certain weight categories but not others, providing limited evidence that length of ISI may in par, control fecundity and egg size in this species. Ovarian recrudescence was classified into ten distinct developmental stages based upon oocyte size, biochemical properties and structure. This classification scheme was comparable to classification schemes developed for other teleosts but represents the first detailed description of oocyte growth in a substrate-spawning tilapia. Radioimmunoassay and stereological analysis provided valuable and novel data concerning the dynamics of ovarian development in this species. Levels of 17ßoestradiol (E2) and testosterone (T) peaked within 6 days of spawning, suggesting that vitellogenesis began as early as day 2 or 3 post-spawning. By day 8, ovaries were dominated by large late-vitellogenic/maturing oocytes (stages 6 & 7) occupying 60 - 70% of the ovary. Gonadosomatic index (GSI) reached maximal levels by day 14. Since the proportion of stage 6/7 oocytes exhibited little change from day 8 onwards, it is suggested that pre-vitellogenic oocytes are recruited into vitellogenic growth immediately after spawning and complete vitellogenesis as early as day 8 postspawning. Analysis of serial-spawning fish found that initial post-spawn E2 and T peaks (on days 2 - 6) were much lower after the second spawning. Sex steroid levels were also found to be suppressed in confined T. zillii (i.e. where stocking densities were > lOkg/m3). Confined females failed to spawn but displayed a marked tendency to do so after transfer to individual aquaria. Serum E2 and T were suppressed during confinement but increased rapidly following transfer to individual aquaria (coincident with resumed spawning activity). It is suggested that levels of E2 and T under confinement are not sufficient to allow completion of vitellogenic growth and are most probably suppressed via a pheromonal mechanism. Finally, the present study investigated the effect of prolonged food restriction on various aspects of reproduction. T. zillii were rationed from first feeding and throughout the following 17 months. Despite very large differences in fish size, no significant differences were detected in total fecundity, egg diameter nor total egg volume once data had been adjusted for differences in fish size. These data suggest that despite very large differences in food availability throughout the periods of sexual differentiation and on-growing, investment in reproduction remained relatively consistent. It appeared that during food restriction, T. zillii sacrificed body weight and growth so as to maintain reproductive investment. In summary, this study provides valuable and novel information regarding the reproductive physiology and endocrinology of female T. zillii and suggests that this species may be a suitable 'model' species for future work on fecundity and ovarian development.
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Reprodução induzida e desenvolvimento inicial do Jundiá Leiarius marmoratus (PISCES: SILURIDAE)Mira López, Tatiana María [UNESP] 14 August 2014 (has links) (PDF)
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000829179.pdf: 3130784 bytes, checksum: 1aceab1f866909bd2e72384a0686f2cc (MD5) / O Jundiá Leiarius marmoratus é um peixe siluriforme da família Pimelodidae, com migração reprodutiva durante a época de chuvas e que ocorre nas bacias dos rios Amazonas e Orinoco. É uma espécie de grande valor econômico por suas características zootécnicas favoráveis, como pouco canibalismo na fase de larvicultura e boa aceitação de alimentos secos na fase adulta. Pode ser uma espécie vulnerável às alterações de hábitat em função do comportamento essencialmente reofílico em pelo menos uma fase do seu ciclo de vida. Neste contexto, estudos que possibilitem a reprodução adequada em cativeiro e o conhecimento da biologia do desenvolvimento inicial da espécie são extremamente necessários, visando produzir juvenis para a aquicultura ou para subsidiar os programas de conservação das suas populações. O presente estudo tem como objetivo estabelecer um protocolo de reprodução em cativeiro com duas substâncias hormonais, extrato bruto de hipófise de carpa (EHC) e Ovopel® (OVO: mGnRHa + metoclopramida), e descrever o desenvolvimento de embriões e o crescimento das larvas do L. marmoratus. Para o estabelecimento dos protocolos de indução à reprodução, machos e fêmeas adultos foram selecionados com base na observação de características externas indicadoras de maturidade reprodutiva, como ventre abaulado nas fêmeas e liberação de sêmen nos machos. Os machos foram injetados com OVO na dosagem total de 2,5 mg.kg-1. Nas fêmeas foram testadas duas substâncias indutoras: um grupo foi injetado com EHC na dosagem total de 5,5 mg.kg-1 e um segundo grupo foi injetado com OVO na dosagem total de 5,5 mg.kg-1. As fêmeas responderam eliminando ovócitos com 175,9 e 177,2 horas-grau para EHC e OVO, respectivamente, a uma temperatura média da água de 25,5 ± 8,8 °C (p>0.05). O diâmetro dos ovócitos ovulados foi de 665 ± 3,11 μm. Parâmetros reprodutivos tais como fecundidade total e relativa e fertilidade foram ... / The Jundiá (Leiarius marmoratus) is a siluriform fish of the family Pimelodidae with reproductive migration during the rainy season, which occur in the basins of the Amazon and Orinoco rivers. It is a species of great economic value for its favorable husbandry characteristics, as little cannibalism in hatchery phase and good acceptance of dry foods in adulthood. It may be a vulnerable species due to changes in habitat because its reofilic behavior in at least one stage of its life cycle. In this context, studies that provide an appropriate captive breeding and knowledge of the biology of early development of the species, are sorely needed, aiming to produce juveniles for aquaculture or to support conservation programs their populations. The present study aims to establish a protocol for captive breeding with two hormonal substances, crude carp pituitary extract (EHC) and Ovopel ® (OVO: mGnRHa + metoclopramide), and describe the development of embryos and growth of larvae L. marmoratus. To establish the induction and reproduction protocols, males and females were selected based on observing external characteristics indicative of reproductive maturity, as bulging belly in females and emission of semen in males. Males were injected with OVO in total dosage of 2.5 mg.kg-1. In females, two inducing substances were tested: one group was injected in total dosage of 5.5 mg.kg-1 EHC and a second group was injected in total dosage of 5.5 mg.kg-1 of OVO. Females responded with oocytes elimination with 175.9 and 177.2 hours-degree for EHC and OVO at an average water temperature of 25.5 ± 8.8 ° C (p> 0,05). The diameter of ovulated oocytes was 665 ± 3.11 μm. Reproductive parameters such as the total and relative fecundity, and fertility were the same for both inducing substances (p> 0.05), with values of 612,000 and 605,400 oocytes.female-1 (fecundity), 125,800 and 132,000 oocytes.kg-1 body weight of the female (fecundity on weight) and 74.7 ...
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Avaliação das características seminais e criopreservação do sêmen de Pseudoplatystoma corruscans (Siluriforme pimelodidae)Velarde, Johanna Maritza Cano [UNESP] 05 February 2013 (has links) (PDF)
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velarde_jmc_me_sjrp.pdf: 664273 bytes, checksum: a0c6ea45c234c6717088c72679615656 (MD5) / O pintado Pseudoplatystoma corruscans é uma espécie com ampla distribuição na América do Sul e de grande valor comercial. P. corruscans necessita migrar para reproduzir e, atualmente, apresenta seus estoques comprometidos devido às alterações dos rios, construção de barragens e pela sobre-pesca. Os objetivos são analisar as características espermáticas e desenvolver um método de congelamento para o sêmen de P. corruscans. Para isso, catorze machos maduros de pintado foram selecionados e induzidos hormonalmente à espermiação. Foram avaliadas as características seminais do sêmen fresco (cor, concentração espermática, motilidade subjetiva). Para o sêmen descongelado foi utilizado o sistema CASA (Computer Assisted Sperm Analisis), onde se fez a verificação da motilidade seminal. Para o desenvolvimento dos protocolos de criopreservação, utilizou-se uma solução diluidora composta de glucose (5,0g), gema de ovo (10%), crioprotetor (DMSO e DMA a 8% e 10%) e água destilada (a.d.q.s). O material espermático foi coletado em dois locais, na Estação de Hidrobiologia e Aquicultura da Usina Hidroelétrica de Jupiá, Castilho, SP, onde as análises do sêmen fresco apresentaram sêmen de cor branco, muito diluído com pouca viscosidade e um volume seminal 4,6±1,5 (mL); a motilidade total espermática média foi de 92,3±9,7%; a concentração espermática média de 85,7 x 10 6 ± 35,49 sptz/mL; e um tempo de ativação de 35 segundos. O material espermático coletado no CEPTA-ICMBIO apresentou uma cor branca com alta viscosidade e um volume seminal de 7±2,3 (mL); foi encontrada uma concentração espermática média de 111,458 x 10 6 ±6,71 espermatozoides/mL; uma motilidade total espermática média de 92,4±5,2%; e um tempo médio de ativação de 32,33±4,0 segundos. As análises da motilidade... / he pintado Pseudoplatystoma corruscans is a species with wide distribution in South America and of great commercial value. P. corruscans need to migrate to reproduce, and currently has compromised their inventories due to changes in rivers, dams and overfishing. The goal, analyze the sperm characteristics and develop a method for freezing semen of P. corruscans. For this, fourteen of mature males were selected and painted to hormonally induced spermiation. We evaluated the seminal characteristics of fresh semen (color, sperm concentration, motility subjective). The thawed semen was used CASA system (Computer Assisted Sperm Analysis), where he made the seminal verification motility. For the development of cryopreservation protocols, we used a diluting solution consisting of glucose (5.0 g), egg yolk (10%), cryoprotectant (DMSO and DMA 8% and 10%) and distilled water (adqs). Spermatic material was collected at two sites in Hydrobiology and Aquaculture Station Hydroeletric Jupiá, Castilho, BC, where the fresh semen analysis showed semen color white, diluted with very little viscosity and a seminal volume 4.6 ± 1.5 (ml), sperm motility overall average was 92.3 ± 9.7%, the average sperm concentration of 85.7 ± 35.49 x 106 SPTZ / mL, and an activation time of 35 seconds. The material collected in the spermatic CEPTA-ICMBIO had a white color and light brown with high viscosity and a seminal volume of 7 ± 2.3 (ml), sperm concentration was found an average of 111.458 ± 6.71 x 106 sperm / mL; one sperm motility overall average of 92.4 ± 5.2%, and an average time of activation of 32.33 ± 4.0 seconds. Analysis of the motility after thawing showed a decrease in sperm motility by prior activation due to high level of urine in fish. And when you compare the two treatments with cryoprotectants DMSO and DMA were no... (Complete abstract click electronic access below)
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Life History Allocation of Energy to Growth and Reproduction in Gizzard Shad, Dorosoma cepedianum, in North Central TexasFagan, Joseph A. 12 1900 (has links)
Life history allocation of energy to growth and reproduction was determined for female gizzard shad. Absolute caloric energy allocated to eggs increased with age. The relative amount of production energy directed to reproduction increased with age up to 5 years and then decreased. Seasonal variation in lipids was studied. Quantitative changes occurred in ovarian lipids during the reproductive cycle. Carcass lipids varied seasonally. Age of sexual maturity was 3 years. Delayed maturity is attributed to high allocation of energy to growth enabling shad to outgrow intense competition and predation in pre-reproductive ages; there is little competition and predation in reproductive shad. Growth rates and condition factors indicated constant availability of food seasonally.
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Studies on the American shad (Alosa sapidissima, Wilson) in the St. John River and Miramichi River, New Brunswick : with special reference to homing and r-K selectionCarscadden, James Eric. January 1975 (has links)
No description available.
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The role of male competition and female choice in the mating success of a Lek-breeding Southern African Cichlid fish Pseudocrenilabrus Philander (Pisces: Cichlidae)Chan, Tin-Yam January 1988 (has links)
A lek-breeding cichlid fish Pseudocrenilabrus philander was studied experimentally. Females in choice-chamber experiments showed no active choice for male size and colour, or for other male attributes, but preferred males which courted most actively. In a laboratory lek, the significant determinants of the strongly skewed mating success in males were territory size, side-shake and female chasing frequency. Together these three variables explained 79% of the variation in male mating success, with territory size alone accounting for 75% of the variation and the other two variables each accounting for 2% of the remaining variation. As there was no difference in territory quality in the laboratory lek, territory size became the principal measure of the effect of male-male competition since it was directly related to dominance. Both side-shake and female chasing could be identified as the basic factors influencing female choice, as they had an immediate effect on the display-response mating system of females. Thus, the relative importance of these three variables indicated that sexual selection in this particular lek mating species operated chiefly through the agency of intrasexual competition for dominance. However, both female behaviour and their requirement for a prolonged pre-spawning courtship had the effect of promoting male rivalry and favouring mating with dominant males. Although the intense male competition excluded subordinate males from practising normal courtship behaviour, competitively inferior males might "make the best of a bad situation" by facultatively adopting an alternative sneaking tactic to gain access to females. Spawning intrusions by females to steal freshly-laid eggs also occurred frequently. However, territorial males appeared to be relatively more tolerant of female intruders than male sneakers. Interference during spawning could lead to a longer pre-spawning courtship and even multiple-mating by females. The results of the present study and the behavioural evidence shown by males and females did not support the ʺrunaway selection modelʺ of the mating pattern in terms of sexual selection in leks, but conformed to the rival ʺwar propaganda modelʺ
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Studies on the American shad (Alosa sapidissima, Wilson) in the St. John River and Miramichi River, New Brunswick : with special reference to homing and r-K selectionCarscadden, James Eric. January 1975 (has links)
No description available.
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Effect of dietary lipid sources on the reproductive performance of Nile tilapia Oreochromis niloticusHajizadeh Kapateh, Ali January 2009 (has links)
Traditionally, fish oil (FO) has been used extensively in aquafeeds. The stagnation in global fish oil production coupled with an increased demand for its use in aquaculture feeds, especially salmonid feeds, has greatly inflated fish oil prices. Therefore, in order to sustain the rapid growth of the tilapia industry, the dependence on these commodities in feeds should be reduced through use of cheaper and more sustainable sources of dietary lipids, such as palm oil. This study therefore investigated several, previously poorly understood, effects of palm oil on reproductive performance of the commercial tilapia species, Oreochromis niloticus; which currently ranks as second most popular species in world aquaculture. In the present study broodstock were fed on experimental diets at full and half ration regimes throughout their entire life cycle from exogenous feeding. Studies were conducted in standardised and controlled hatchery conditions, thereby reducing the potential influence of environmental variations. First feeding O. niloticus fry were fed on four diets, cod liver oil (D 1), palm oil (D 2), mixed palm and cod liver oil (D 3) (9:1 ration) and a commercial trout diet as control (D 4) (Skretting, U.K.) on a reducing ration based on fish size. The present study investigated the effect of dietary lipid sources on (1) growth performance, (2) biochemical composition of eggs (total lipid and fatty acid composition), (3) morphological parameters of eggs (total and relative fecundity, egg size, egg weight and EW:BW), (4) larval quality (larval length and weight) and (5) oocyte recruitment and its associated sex steroid hormones. Experimental diets and feeding ration significantly influenced (p<0.05) the growth performance over a period of 120 days. Total lipid and fatty acid composition of eggs originating from broodstock fed on palm oil, mixed palm and cod liver oil (9:1) or a control diet were not significantly different (P>0.05) when fed at either full (3% BWday-1) or half ration (1.5% BWday-1). The present study, however, confirmed that fatty acid composition of fish eggs reflected the fatty acid composition of the diet, although specific fatty acids were selectively utilized or retained in the eggs. The mean inter-spawning interval (ISI) increased with increasing fish size and averaged 14, 19 and 24 days for fish fed on palm oil, mixed palm and cod liver oil or control diets, respectively. The shortest ISI observed was 7 days for fish fed a palm oil diet. Total fecundity ranged from 660 - 820 eggs/clutch. Mean total fecundity was 750, 820 and 660 eggs/clutch for fish fed a palm, mixed palm and cod liver oil or a control diet, respectively, but these differences were not significant (P>0.05). However, relative fecundity and egg weight to body weight rates as a percentage (EW: BW) were found significantly differ (p<0.05) between fish fed the control diet and experimental diets. Mean egg diameter (2.2 mm) was not significantly influenced (p>0.05) by experimental diets. The egg volume, egg dry and wet weight, fertilisation and hatching rate were also not significantly different between fish fed the experimental diets. Oocyte development was classified into distinct stages based upon oocyte size, biochemical properties and structure. The recrudescence to these stages was not significantly influenced by broodstock fed experimental diets either at full or half ration. Steroid hormones and histological analyses provided valuable data concerning the oocyte development and recruitment in this species. Levels of 17ß-oestradiol (E2) and testosterone (T) peaked within 6 days of spawning, suggesting that vitellogenesis began as early as day 2 or 3 post-spawning. By day 6, ovaries were dominated by large late-vitellogenic/maturing oocytes (stages 6 & 7) occupying about 70% of the ovary. Gonadosomatic index (GSI) reached maximal levels by day 6. It is suggested that pre-vitellogenic oocytes are recruited into vitellogenic growth immediately after spawning and complete vitellogenesis on day 6 post-spawning. Finally, the present study investigated the effect of food restriction at two rations (full and half) on broodstock reproductive performance. Oreochromis niloticus were rationed from first feeding and throughout their life-cycle. The dietary regime, full ration (3%) and half ration (1.5%), influenced fish size but despite this variation no significant differences (p>0.05) were detected in total lipid and fatty acid composition in the eggs, total fecundity, egg diameter, total egg volume and larval size. These results suggested that despite large differences in food availability throughout their life cycle, investment in reproduction had remained remarkably consistent. It appeared that during food restriction, O. niloticus sacrificed body weight and growth so as to maintain reproductive investment. In summary, this study provides valuable information using a novel experimental design on the effects of dietary lipid sources on reproductive performance of female O. niloticus. Substituting palm oil for fish oil as the dietary lipid source and reducing ration by half (1.5% BWday-1) had no significant effect on reproductive performance. Therefore it is suggested that under controlled conditions, lipids of non-marine origin, such as palm oil, can be successfully substituted for broodstock diets. Halving feed requirement should also increase profitability of seed production. KEYWORDS: Tilapia; O. niloticus; palm oil; diet; fecundity; spawning periodicity; oocyte recruitment; reproductive performance.
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