Growth and survival of tilapia Oreochromis niloticus (Linnaeus, 1758) submitted to different temperatures during the process of sex reversal

Abstract

The objective of this research was to evaluate the sex reversal technique using 17 --methyltestosterone (MT) hormone, submitted to temperature modification of fry Nilo tilapia storage, aiming to get the data of sex reversal combined with growth performance and fry survival. The experiment was performed at UFLA Fish Culture Station, using tilapia fry (0,008 ± 0.002 g e 0,9 ± 0.1 cm) obeying a totally randomized experimental delineation in a factorial scheme 4x4, in 4 temperatures (26º, 28º, 30º, 32ºC) and 4 hormonal doses (0, 20, 40, 60mg of MT/kg of ration) during 28 days, with 5 repetitions. As temperature raised, weight gain rate, size and survival increased (p<0.01); however, this temperature raise was not effective in modifying males ratio (p>0.01), which occurred only due to the used hormone treatment. The dose of 40 mg of MT/kg of ration provided similar results to those of 60mg of MT/kg of ration. Hence, the temperature band from 26º to 32ºC does not affect sex reversal rate, but temperatures around 30ºC improves the performance of tilapias related to the growth and survival, and the dose of 40 mg of MT/kg of ration is enough to achieve monosex populations.Index terms: Tilapia, 17 -methyltestosterone, temperature. RESUMOObjetivou-se, neste trabalho, avaliar a técnica de inversão sexual utilizando hormônio 17 -metiltestosterona (MT), submetidas à modificação da temperatura de estocagem das pós-larvas de tilápia, visando obter os melhores dados de inversão sexual aliado à performance de crescimento e sobrevivência das pós-larvas. O experimento foi conduzido na Estação de Piscicultura da UFLA, utilizando pós-larvas (0,008 ± 0,002 g e 0,9 ± 0,1 cm) de tilápia em delineamento experimental inteiramente casualizado em esquema fatorial 4x4, com 4 temperaturas (26º, 28º, 30º e 32ºC) e 4 doses hormonais (0, 20, 40 e 60mg de MT/kg de ração) durante 28 dias, com 5 repetições. À medida que se elevou a temperatura, a taxa de ganho de peso, o tamanho e a sobrevivência foram maiores (p<0,01); entretanto, esse aumento na temperatura não foi suficiente para alterar a proporção de machos (p>0,01), que ocorreu apenas em função do hormônio utilizado. A dose de 40 mg de MT/kg de ração proporcionou resultados semelhantes aos da dose de 60 mg de MT/ kg de ração. Portanto, a faixa de temperatura entre 26º e 32ºC não influencia na taxa de inversão sexual, mas temperaturas em torno de 30ºC melhoram o desempenho das tilápias quanto ao crescimento e à sobrevivência, e a dose de 40 mg de MT/kg de ração é suficiente para a obtenção de populações monossexo.Termos para indexação: Tilápia, 17 -metiltestosterona, temperatura.

Effect of rearing temperature and hormone treatment on sex ratio, survival and body weight of Oreochromis niloticus fry

“…In the same trend, increasing rearing water temperature to 30 or 35°C without 17α-MT (C30H0 and C35H0) significantly increased mortality rate to 14.00 and 14.33% after one week; 15.33 and 15.00% after two weeks; 15.33 and 15.17% after three weeks and 15.83 and 16.83% after four weeks of treatment. These results are in agreement with those observed by Drummond et al, (2009) who found that, the values of survival (%) of O. niloticus after 28 days of treatment there was significant interaction of temperatore (26, 28, 30 and 30°C) and hormonal doses (0, 20, 40 and 60 mg17α-MTkg diet).…”

“…The combined effect of rearing water temperature and 17α-MT treatment indicated a significant increase in male ratio compared to the effect of water temperature or 17α-MT alone and these results showed the possibility of reducing hormone treatment period from 4 to 2 weeks by increasing rearing water temperature to 30 or 35°C with obtaining an appropriate male population (93.33 and 96.67%, respectively) and this could be reduce hormone costs and its problems in producing sex reversal of O. niloticus fry. On the other hand, Drummond et al, (2009) found no significant interaction between temperatore (26, 28, 30 and 30°C) and hormonal doses (0, 20, 40 and 60 mg17α-MTkg diet) for sex ratio of O. niloticus fry used for sex reversal.…”

“…Our ressults are in agreement with many previous studies. Drummond et al, (2009) found a significant interaction between temperatore (26, 28, 30 and 30°C) and hormonal doses (0, 20, 40 and 60 mg17α-MTkg diet) for weight gain of O. niloticus fry used for sex reversal (p <0.01). Macintosh et al, (1985) indicated that, there were significant differences between hormone treated and untreated tilapia fry.…”

Aspectos Técnológicos E Perspectivas De Desenvolvimento Do Cultivo De Tilápia No Brasil

“…Tilápia é o nome genérico de um grande número de espécies de peixes da espécie de ciclídeos (DRUMMOND;MURGAS;VICENTINI, 2009). A distribuição original deste grupo foi no centro-sul da África para o norte na Síria (POP-MA; PHELPS, 1998), portanto da família Cichlidae, nativo do continente Africano e da Ásia Menor (GURGEL, 1998).…”

Comparative Study on Growth and Survival Rate of Oreochromis niloticus (Linnaeus 1758) Treating with Supplementary Feed at Different Feeding Regime

“…The survival rate of O. niloticus was is higher with natural food compared to artificial feed [12]. Remarkable growth and survival performance of tilapia have been observed at around 30ºC [13]. The growth of fish performs better in p H ranging from 5.66-7.66 [14].…”