Altevir Signor

Energia Digestível para Larvas de Tilápia-do-Nilo (Oreochromis niloticus) na Fase de Reversão Sexual

This experiment was conducted to evaluate different levels of digestible energy on the performance of Nile tilapia larvae (Oreochromis niloticus) during the sexual reversion phase. Three hundred and seventy-five larvae with initial average length and weight of 21.0±4.0 mg and 1.19±0.72 cm, respectively, were allotted to 25 30L-aquarium. A completely randomized design with five treatments and five replicates was used. The aquarium with 15 larvae was the experimental unit. The diets were formulated to contain levels of 3,300, 3,525, 3,750, 3,975, and 4,200 kcal/kg of digestible energy and to be isoprotein (38.6% digestible protein). The animals were fed ad libitum five times a day. At the end of the experiment, the averages of weight (PF), survival rate (SO), condition factor (FC) and length (CF) were analyzed. Linear reduction of fishes PF and CF, as the dietary digestible energy levels increased, was observed. No differences on fish SO and FC of different treatments were observed. Deleterious effects on performance due to the increasing dietary digestible energy levels were noticed for Nile tilapia larvae during the sexual reversion.

Energia digestível para alevinos de tilápia-do-nilo (Oreochromis niloticus)

The different levels of digestible energy on the performance of Nile tilapia (Oreochromis niloticus) fingerlings were evaluated. One hundred and twenty-five fingerlings averaging initial length and weight of 0.62±0.12 and 3.25±0.25 cm were allotted to 25 30L-aquariums, as a completely randomized design with five treatments and five replicates (an aquarium with five fingerlings was considered the experimental unit). The diets, formulated to be isonitrogenous (30% of digestible protein), isophosphorous and isocalcium, contained 3,300, 3,525, 3,750, 3,975, and 4,200 kcal/kg of digestible energy. The amount of diet was fed of 10% of biomass four times a day. The abiotic parameters (pH, dissolved oxigen - DO, and electric condutivity - EC) were weekly measured at afternoon and the temperature was was daily mensured. The following values were observed: pH of 7.91±0.19, DO of 8.00±0.05 mg/L, EC of 92.11±2.27 µS/cm, and temperature of 25.61±0.90oC. At the end of experiment, means of final weight, weight gain, final length, apparent feeding conversion, survival rate and condition factor were analyzed. No significant differences on fingerling perfomance were found across the treatments. It can be included from 2,900 to 3,400 kcal of ED/kg in the diet of Nile tilapia fingerlings.

Hidrolisado proteico de peixe em dietas para pós-larvas de tilápia-do-nilo

The objective of this work was to determine the apparent digestibility coefficient (ADC) of crude protein, crude energy, fat, and dry matter of fish protein hydrolysate (FPH), made of by-products of Nile tilapia (Oreochromis niloticus) and whole sardines (Cetengraulis edentulus), and to evaluate the productive performance and muscle fiber growth of Nile tilapia post-larvae. Two trials were conducted, the first one to determine the digestibility in 120 fingerlings (70.0±2.0 g), and the second one to evaluate the productive performance of 375 post-larvae, with three days of age, which were distributed in 25 aquaria with 30 L of useful volume. Five diets were prepared based on vegetable ingredients, to which fish were included at 0, 2, 4, 6, and 8% FPH. For the evaluation of muscle growth, eight fish of each experimental unit were used. The ADC values found were: 98.29% for dry matter; 99.28% for crude protein; and 99.13% for gross energy. The best zootechnical response for the productive performance resulted from the treatment with the inclusion of fish hydrolysate at 4.75%. The diets affected the frequency of the muscle fiber diameters, mainly the growth by hyperplasia. FPH can be efficiently used, and its inclusion at 4.75% is indicated in the diets for Nile tilapia in the post-larvae stage.

Farinha de carne e ossos na alimentação de larvas de tilápia do Nilo

The present study evaluated the inclusion of meat and bone meal (FCO) in Nile tilapia larvae feeding. The diet was formulated to be isoproteic (38.6% DP) and isocaloric (3500kcal DE kg-1) with different FCO levels at 0; 5; 10 and 15%. A 30-day trial was carried out in a complete randomized design with 360 Nile tilapia larvae (6.59 ± 0.02mg and 0.90 ± 0.08cm) distributed in 24 50l-aquaria and fed until satiation five times a day at 8h00, 10h30, 13h00, 15h30 and 18h00. At the end of the experiment the average final weight (PF), final length (CF), standard length (CP) and survival (%) (SO) were evaluated and the data was submitted to a regression analyses. The Inclusion level of up to 15% of FCO in the diet did not influence larvae weight gain. However, the higher CP was observed in larvae fed with the highest level of FCO inclusion in diet. Therefore, it can be used a total of up to 15% of FCO inclusion in Nile tilapia larvae feeding ration.

Water Quality in a Reservoir used for Fish Farming in Cages in Winter and Summer Periods

This study aimed to evaluate the vertical dynamics of the water quality, in different seasons (summer and winter), in an aquaculture area of the Iguassu River electric plant reservoir (Paraná/Brasil). Water sampling was done monthly. Samples were collected from the water column layers (epilimnion, metalimnion and hypolimnion.). Water temperature, (pH), dissolved oxygen, biochemical oxygen demand, nitrite, chlorophyll, total phosphorus, orthophosphate and ammonia were the parameters evaluated. Data from each parameter were submitted to ANOVA and to Tukey’s test at the 0.05 significance level. Correlation analysis between the variables was performed using the Spearman’s test. Multivariate approach was adopted performing Royston’s multivariate normality test. A clustering analysis was performed using Ward’s minimum variance method with a Euclidean distance matrix. This study showed that fish farming did not alter the water quality during summer and winter. Heterogeneity in summer and homogeneity in winter are observed between the layers of the water column.

Vitamin a supplemented diet for pacu fingerlings

Vitamins are present in small amounts in food and are essential for the organic balance of fish. Liposoluble vitamins are stored in the liver and may lead to hypo or hypervitaminosis which in both cases can generate complications to animal homeostasis. This study aimed to evaluate the effects of vitamin A supplementation in the diet of pacu fingerlings (Piaractus mesopotamicus). A total of 240 fingerlings with the initial average weight of 17.55 ± 3.22 g were randomly distributed in 20 500 L-circular tanks. Diets were supplemented with retinol acetate (1,000,000 IU of vitamin A g-1) to contain 0, 3,000, 6,000, 9,000, and 12,000 IU of vitamin A kg-1 of diet. The fish were fed ad libitum. Productive performance, carcass yield, visceral fat, hepatosomatic ratio, carcass chemical composition, hematology blood parameters, and liver histology were evaluated. The quadratic effect was observed on final weight and apparent feed conversion with optimum levels at 6,583 and 5,555 IU of vitamin A kg-1 of feed, respectively. There was no influence of vitamin A supplementation on survival, carcass chemical composition, hematology, and liver histology. The minimum supplementation of 5,555 IU of vitamin A kg-1 of ration is indicated to obtain enhanced results in weight gain and apparent feed conversion in pacu fingerlings.

Desempenho reprodutivo de jundiá alimentado com dietas com sorgo suplementadas com fitase

The objective of this work was to evaluate the reproductive performance of silver catfish (Rhamdia quelen) fed diets containing sorghum, as a replacement for corn, supplemented or not with phytase. The experiment was carried out with 360 fish, with 16.02±0.58 g mean initial weight, fed diets in which low-tannin sorghum replaced corn at 0, 50, and 100%, with or without phytase supplementation (1,500 FTU per kilogram of feed). Diets supplemented with phytase or with 100% sorghum led to a reduction of visceral fat deposition and hepatic mass in males. In females, similar results were observed for diets containing phytase. Females fed sorghum-only diets, supplemented or not with phytase, had bigger oocytes. Males and females at the developing and final stages of gonadal maturation were found in all treatments. The replacement of corn by sorghum affects neither semen quality nor the fertilization rate of gametes. Therefore, complete replacement of corn with low-tannin sorghum in the diet can be performed without compromising the reproductive performance or the somatic indexes of silver catfish.

Lysine in the diet of common carp (Cyprinus carpio) fingerlings

O presente estudo teve por objetivo determinar a exigência de lisina para alevinos de carpa comum (Cyprinus carpio). Foram distribuídos inteiramente ao acaso 280 alevinos de carpa comum com peso e comprimento inicial médio de 0,62 ± 0,05 g e 3,38 ± 0,11 cm, respectivamente, em 28 tanques-rede quadrados com volume útil de 150 litros, dispostos no interior de um tanque circular de alvenaria com capacidade para 25 m3 de água (sete tratamentos e quatro repetições). Os peixes foram alimentados até a saciedade aparente quatro vezes ao dia com dietas isproteicas e isoenergéticas suplementadas com lisina nas concentrações de 1,58; 1,81; 2,05; 2,29; 2,53; 2,76 e 3,0% da dieta por 57 dias. Ao final do estudo foi avaliado o desempenho produtivo, sobrevivência e composição centesimal da carcaça dos peixes. Os dados obtidos foram submetidos a análise de regressão (p<0,05) e ao teste múltiplo de média Tukey. A análise do platô de resposta linear (LRP) foi aplicado adicionalmente. A suplementação de lisina melhorou (p<0,05) o peso final médio, ganho de peso médio e taxa de crescimento específico e a partir de 2,29% de suplementação de lisina na dieta prejudicou a eficiência alimentar dos peixes. A exigência de lisina para alevinos de carpa comum é de 1,89% da dieta ou 4,73% da proteína bruta para obtenção do melhor crescimento. Palavras-chave: aminoácidos; nutrientes; exigências; ração. ABSTRACT The aim of the present study was to determine the lysine requirement of common carp fingerlings. Two hundred and eighty common carp fingerlings, with mean weight and mean length initial of 0.62 ± 0.05 g and 3.38 ± 0.11 cm, respectively were randomly distributed into 28 squares net cages of 150 litres arranged inside a masonry circular tank with water capacity of 25 m-3 (seven treatments and four replications). The fish were fed until apparent satiation, four times per day, with isoproteic and isoenergetic diets supplemented with lysine at 1.58, 1.81, 2.05, 2.29, 2.53, 2.76, and 3.0% of the diet for 57 days. Productive performance, survival rate, and chemical composition of the fish body were evaluated at the end of the study. The data obtained was subjected to regression analysis and, when significantly different (P<0.05), the Tukey multiple comparison test was used. Additionally, linear response plateau (LRP) analysis was performed. Lysine supplementation significantly improved (P<0.05) mean final weight, mean weight gain, and specific growth rate. However, lysine levels above 2.29% compromised the feed efficiency. Lysine requirements of common carp fingerlings were found to be 1.89% of the diet or 4.73% of the crude protein in the diet for obtain better growth.

Suplementação de vitamina B12 na dieta de alevinos de piauçu (Leporinus macrocephalus)

As vitaminas sao essenciais para o adequado funcionamento dos organismos, sendo importantes em diversas reacoes do metabolismo e influenciando na saude do animal. O objetivo do presente trabalho foi avaliar niveis de suplementacao de vitamina B12 em dietas para alevinos de piaucu (Leporinus macrocephalus). Foram utilizados 300 alevinos de piaucu, com peso inicial de 0,44 ± 0,12 g, distribuidos inteiramente ao acaso em 20 tanques-rede (cinco tratamentos e quatro repeticoes), com 150 litros de volume util, dispostos em um tanque circular de alvenaria de 25 m3. Formulou-se uma dieta basica contendo 36% de proteina digestivel e 3.600 kcal/kg de energia digestivel para a tilapia, sendo confeccionadas, a partir destas, cinco dietas experimentais suplementadas com vitamina B12 (0,00; 0,02; 0,04; 0,08 e 0,16 mg de cianocobalamina(1,0%)/kg de racao). Os peixes foram alimentados quatro vezes ao dia (as 8, 11, 14 e 17 horas). Os parâmetros de sobrevivencia e conversao alimentar nao apresentaram diferencas (p > 0,05) em funcao dos niveis de suplementacao de vitamina B12. No entanto, os resultados de peso final, ganho em peso e comprimento final apresentaram diferenca entre os niveis de vitamina B12 na dieta. Os melhores resultados foram observados nos animais alimentados com as racoes isentas de vitamina B12, porem, nao diferiram dos animais alimentados com a suplementacao de 0,08 e 0,16 mg de vitamina B12/kg de dieta. Concluiu-seque em racoes para alevinos de piaucu, nao se faz necessario suplementar as racoes com vitamina B12 na dieta, quando esta apresenta farinha de origem animal na sua composicao.