Made available in DSpace on 2017-07-10T18:13:33Z (GMT). No. of bitstreams: 1 Ilson Mahl.pdf: 851208 bytes, checksum: ee08605c796aa93ac70131d19f892763 (MD5) Previous issue date: 2010-08-23 / Fundação Araucária / This study aimed to evaluate formats and areas of feeders used in cages on production performance, uniformity of lots, physical and chemical characteristics and body indexes of Nile tilapia. It was used 2700 juvenile of tilapia with mean weight of 5.95 ± 1.23 g, distributed in 27 cages (0.5 x 0.5 x 1.0 m) in a completely randomized design in a factorial model, feeders with two formats (square and circular) and four areas (100, 75, 50 and 25%) and a control (feeder free) with three replications. After 64 days evaluated the performance parameters of weight gain, total length, specific growth rate, survival, feed conversion and uniformity of lots. The levels the dry matter, crude protein, ether extract and ash were evaluated from the eviscerated fish. The viscerossomatic, hepatossomatic and visceral fat indexes were also evaluated. The format of feeders did not influence (P>0.05) the performance parameters of tilapia juvenile, however, the feeders area did affect (P<0.05) the survival, with the highest 98.3% for feeders with area of 50%. It was observed lower values of weight gain (25.45 g) and length (11.50 cm) of fish reared in cages at absent of feeders. The feed conversion was higher (P<0.05) for fish in cages without feeder compared to the others. The fish reared in cages with square feeders with area of 75% and reared absent of feeders showed the highest humidity levels of 71.27% and 74.13% respectively. The interaction format and area also influenced (P<0.05) the crude protein of fish, with values of 17.02% and 17.34% respectively for cultures containing feeders circular with area of 75%, and squares with area of 50%. There were no significant differences (P>0.05) for mineral matter, however fish cultured in cages containing squares feeders with area of 100% and circular with area of 50% showed higher values (P<0.05) respectively, 8.83% and 9.48% for ether extract. The format and the area of feeders did not affect (P>0.05) at corporeal indexes, however, fish subjected to cages without feeders had lower hepatossomatic index, viscerossomatic and visceral fat (P<0.05), with values of 10.87, 2.36 and 2.33% respectively. The different areas and formats feeder does not interfere in the productive performance on stage of juvenile Nile tilapia in cages with small volume. Whereas to better utilization of diets on the fish performance it is recommended to use at least one of combinations of size and format of feeder used during cultivation. / O objetivo deste trabalho foi avaliar formatos e áreas de comedouros utilizados em tanques-rede sobre o desempenho produtivo, homogeneidade dos lotes, características físicas e químicas e índices corporais de tilápias do Nilo. Foram utilizados 2.700 juvenis de tilápia com peso médio de 5,95 ± 1,23 g, distribuídos em 27 tanques-rede (0,5 x 0,5 x 1,0 m), em um delineamento experimental inteiramente casualizado em esquema fatorial, com dois formatos de comedouros (quadrado e circular) e quatro áreas (100, 75, 50 e 25%) e, um tratamento controle (isento de comedouro), com três repetições. Após 64 dias avaliaram-se os parâmetros zootécnicos de ganho em peso, comprimento total, taxa de crescimento específico, sobrevivência, conversão alimentar aparente e homogeneidade dos lotes. Avaliaram-se os teores de matéria seca, proteína bruta, extrato etéreo e matéria mineral das carcaças dos peixes eviscerados. Os índices viscerossomático, hepatossomático e gordura visceral também forma avaliados. O formato dos alimentadores não influenciou (P> 0,05) os parâmetros de desempenho de juvenis de tilápia, no entanto, a área de alimentadores afetou (P <0,05) a sobrevivência, com a mais alta de 98,3% para os alimentadores com área de 50%. Observaram-se menores valores de ganho em peso (25,45 g) e comprimento total (11,50 cm) dos peixes cultivados nos tanques-rede isentos de comedouros. A conversão alimentar aparente foi superior (P<0,05) para os peixes dos tanques-rede sem comedouros em relação aos demais. Os peixes cultivados em tanques-rede com comedouros quadrados e área de 75% ou nos cultivos isentos de comedouros apresentaram os maiores valores de umidade de 71,27% e 74,13%, respectivamente. A interação formato área também influenciou (P>0,05) os teores de proteína bruta dos peixes, com valores de 17,02% e 17,34%, respectivamente para cultivos que continham comedouros circulares com áreas de 75% e quadrados com áreas de 50%. Não foram observadas diferenças significativas (P>0,05) para matéria mineral, porém os peixes cultivados em taques-rede com comedouros quadrados com áreas de 100% e circulares com áreas de 50% apresentaram maiores valores (P<0,05) respectivamente, 8,83% e 9,48% para o extrato etéreo. O formato e a área dos comedouros não influenciaram (P>0,05) nos índices corporais, entretanto, os peixes submetidos aos tanques-rede sem comedouros apresentaram menores índices hepatossomático, viscerossomático e de gordura visceral (P<0,05), com valores de 10,87, 2,36 e 2,33%, respectivamente. As diferentes áreas e formatos de comedouro não interferem no desempenho produtivo na fase de juvenis de tilápia do Nilo em tanques-rede de pequeno volume. Considerando um melhor aproveitamento das dietas no desempenho das tilápias, recomenda-se a utilização de pelo menos uma das combinações entre formato e área de comedouro utilizado na fase cultivada.

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.