Desempenho de três linhagens de Tilápia do Nilo (Oreochromis niloticus) em diferentes fases, densidades e níveis de proteína.
The present work objective to evaluate the productive performance of three Nile Tilapia (O. niloticus) lines during the initial and growing phase in different stocking densities also during the final phase with different crude protein levels (25 and 30%). The evaluated lines were: Bouaké, Chitralada and GIFT (Geneticaly Improved Farmed Tilapia). The experiment was carried out in three phases from February to November of 2006. in the first two phases it was used a kind of greenhouse installation, with a total of 500L water box were it was tested three Nile Tilapia lines and three stocking densities (15, 20 and 25 fish per box). In the initial phase, with a lasting of 28 days from February to March of 2006 and (06, 10 and 14 fish per box) during the growing phase with 53 days of lasting from March to April of 2006. Each phase characterized by nine treatments with three replications. The final phase had 204 days and was from April to November of 2006. For so, the fish were individually marked with an electronic Passive Integrated Transponder (PIT) tags implanted in the abdomen, guarantying the secure and permanent identification of fish using a code formed by letters and numbers that allowed the lecture by using an electronic lecture scanner. The final phase last 204 days and was carried out from April to November of 2006. There were used three fish lines totalizing 230 fish that were proportionally divided and allocated in two land tanks of 140m2 each one. Each tank received commercial rations with different crude protein (CP) levels being 25% of CP for one tank and other one with 30% of CP. The water quality parameters kept adequate for the different densities during the first two phases not affecting lines performance. In the initial phase comparing the densities inside the same line, Chitralada and GIFT did not show difference. However, Bouaké line showed sensibility to the stocking density increase with total final length average, final weight and gain weight significantly lower to the higher evaluated density while the surviving rate kept normal levels to this specie phase. The growing phase results to the average final performance showed differences (P< 0.05) among evaluated densities inside the same lines, being the lower density the most efficient. But comparing the same density among the different lines it was not observed significant differences. The different densities showed a straight relation between the increased density and performance reduction. In the final phase the average temperature during the winter contributed to the feed ingestion restriction by fish during the coldest days what could have influenced the lines performance. However, when evaluating the water quality parameters it was observed that the averages for these factors kept satisfactory to the adequate specie growing. The average performance of fish fed with ratio containing 25% of CP were higher in 46.0%, 35.0% and 51.0% for Bouaké, Chitralada and GIFT, respectively, when compared to the fish of the same line that received ration with 30% of CP, showing an inverse relation between CP levels increase and productivity, suggesting a lower CP levels necessity to Nile tilapias diet during the final phase, decreasing the ambient impact with lower nitrogen amounts being lost and also decreasing the cost production since protein is the most expensive ingredient of rations and does not necessary affect the biological value. Comparing the three tilapia lines performance, the GIFT showed to be the most efficient for all evaluates parameters independent of the crude protein level supplied, followed by Chitralada and Bouaké. The most efficient average of GIFT in relation to the others lines reported its potential genetic improvement in relation to the no improved lines.
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| Format: | Thesis/Dissertation biblioteca |
| Language: | Portuguese |
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Universidade Estadual de Maringá. Centro de Ciências Agrárias. Programa de Pós-Graduação em Zootecnia
2007
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| Subjects: | Productive performance, Breeding, Stocking density, Crude protein levels, Níveis de proteína bruta, Desempenho produtivo, Brasil, Densidade de estocagem, Tilápia do Nilo, Melhoramento genético, Oreochromis niloticus, Niloticus niloticus, Nile tilapia, Brazil, |
| Online Access: | http://hdl.handle.net/1834/9848 |
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