Dietetic vitamin a requirements of nile tilapia oreochromis niloticus.

Author(s)

Daniela Ferraz Bacconi

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2003-07-29

Examining board members

Jose Eurico Possebon Cyrino; Margarida Maria Barros Ferreira Lima; Jose Fernando Machado Menten

• Advisor: Jose Eurico Possebon Cyrino

Abstract

Excess dietary fat-soluble vitamins can be accumulated in the liver and cause hypervitaminosis in animals. The aim of this research was to establish the vitamin A requirement for Nile tilapia Oreochromis niloticus, evaluating weight gain and food conversion ratio, and quantifying hepatic retinol deposits in a sex reversed, all male population (R; 13.76 ± 1.21 g) and a mixed sex population (NR; 9.83 ± 2.30 g ). Fish were stocked in 100-L plastic aquaria, in controlled environmental conditions of temperature (25,0 ± 1,0 ºC) and luminosity (12h00m : 12h00m), and fed ad libitum, twice a day, seven days a week, during seventy five days with semi-purified diets supplemented with 0; 600; 1,200; 1,800; 2,400; 3,000; 3,600; 4,200; 4,800 and 5,400 IU of retinol palmitate per kg of diet (Rovimix A 500 Roche ® ; 30 % vitamin A) in a totally randomized experimental design, factorial arrangement 2x10 (n=4). At the end of the experiment all groups were sacrificed and liver tissue excised for the hepatic retinol analyses. Severe signs of nutritional deficiency of vitamin A were observed in fish of treatments 0; 600 and 1,200 IU vitamin A kg -1 diet; moderate signs were also found in fish of treatments 1,800 trough 3,600 IU vitamin A kg -1 diet, both populations. Interactions group*level were not significant (P<0.05) to all analyzed performance variables. Increasing levels of dietary vitamin A influenced final weight and weight gain of the fish (P<0.05), but did not influence feed consumption (P>0.05). A group effect was observed regarding all performance variables (P<0.0001). Hepatic retinol quantification (High Performance Liquid Chromatogaphy) detected vitamin A only in fish fed 5,400 IU of retinol per kg of diet. (AU)