Valéria Rossetto Barriviera Furuya

Fitase na alimentação da tilápia do Nilo (Oreochromis niloticus). Desempenho e digestibilidade

This experiment was carried out to evaluate the effects of addition of different levels of phytase (0, 500, 1500 and 3000 units of active phytase [UFA]/kg diet) in the diets for Nile tilapia (8.88 ± 0.02 g). All diets were fed to satiation daily for 45 days. The phytase level determination was based on the performance and digestibility parameters and was estimated by the quadratic and/or the broken line models. The broken line model showed a better adjustment for phytase levels according to the observed results. Phytase supplementation increased performence, bone minerals, protein digestibility and calcium and phosphorus availability. The best results of performance, bone mineral retentions and digestibility were obtained with 700 UFA/kg of diet.

Aplicação do conceito de proteína ideal para redução dos níveis de proteína em dietas para tilápia-do-nilo (Oreochromis niloticus)

Este estudo foi realizado para se avaliar a reducao dos niveis de proteina em dietas para tilapia-do-nilo (5 a 125 g), adotando-se o conceito de proteina ideal. Cento e sessenta peixes (4,40 ± 0,9 g) foram distribuidos em um delineamento inteiramente casualizado, com quatro tratamentos [25,5; 27; 28,5 e 30% (controle) de proteina digestivel], tres repeticoes e dez animais por unidade experimental. Os aminoacidos sinteticos foram suplementados para se manter as proporcoes de aminoacidos de acordo com o conceito de proteina ideal. Os aminoacidos lisina, metionina e treonina foram suplementados para se obter os niveis de aminoacidos da dieta controle. As dietas foram fornecidas a vontade, durante 83 dias. Nao foram observados efeitos dos niveis de proteina sobre o ganho de peso, a conversao alimentar, o indice hepatossomatico, o peso da gordura visceral, a taxa de sobrevivencia, os niveis de proteina na carcaca e o diâmetro da fibra intermediaria. O aumento nos niveis de proteina resultou em reducao linear na taxa de eficiencia proteica e de retencao do nitrogenio e aumento linear na excrecao de nitrogenio. Foi observado efeito quadratico sobre o rendimento de carcaca e o teor de extrato etereo na carcaca; os melhores valores foram obtidos com 28,40 e 27,31% de proteina na dieta, respectivamente. Concluiu-se que e possivel a reducao do nivel de proteina de 30 para 27,5% em dietas para juvenis de tilapia do Nilo, sem efeitos negativos sobre o crescimento, rendimento de carcaca e a composicao quimica dos files. No entanto, a reducao do nivel de proteina de 30 para 25,5% acarreta reducao no diâmetro das fibras musculares vermelha e branca.

Exigências de lisina digestível para juvenis de tilápia-do-nilo

This trial was carried out to determine the digestible lysine requirements of Nile tilapia juveniles. Ninety- six reverted fishes averaging initial weight of 5.72 ± 0.10 g were fed four diets (29.51% of crude protein and 3,235 kcal/kg of digestible energy) containing increasing levels of L-lysine HCl (0.1, 0.3, 0.5, and 0.7%), during 42 days. The following treatments were evaluated: dietary lysine levels of 1.04; 1.27; 1.51 and 1.741%. Fishes were allotted to 1000-L 16 tanks, as a completely randomized design with four treatments, three replicates and eight fishes per experimental unit. No treatment effects on hepatosomatic index, visceral fat, survival rate and water ether extract in the carcass were observed. The Linear Response Plateau analysis of weight gain and feed:gain ratio versus digestible lysine level yielded an estimated digestible lysine requirement of 1.56 and 1.44% for Nile tilapia juveniles, respectively. Quadratic effect of treatments on carcass yield that increased up to 1.61% of digestible lysine was observed. Considering the performance, it is recommended diets containing up to 1.44% of digestible lysine (5.23% of protein) for Nile tilapia juveniles.

Desenvolvimento de girinos de rã-touro (Rana catesbeiana, Shaw, 1802) cultivados em diferentes densidades de estocagem em tanques-rede

Objetivou-se, nesta pesquisa, avaliar o efeito da densidade de estocagem sobre o desenvolvimento de girinos de ra-touro em tanques-rede. Foram utilizados 360 girinos com peso medio inicial 0,01g e comprimento inicial medio de 0,92±0,06 cm, distribuidos em um delineamento em blocos ao acaso com cinco tratamentos (0,50; 1,00; 1,50; 2,00 e 2,50 individuos/L) e quatro repeticoes, em 20 tanques-rede experimentais (12 L). Foi fornecida dieta com 40,00% de proteina bruta, na proporcao de 8,00% do peso vivo, duas vezes ao dia. Observou-se aumento linear da biomassa por tanque, em funcao da densidade de estocagem. O peso final medio e a taxa de sobrevivencia apresentaram reducao linear, com o aumento da densidade. Observaram-se lotes mais uniformes dos girinos cultivados em menores densidades. A conversao alimentar nao foi influenciada pelas diferentes densidades de estocagem. As variaveis fisico-quimicas da agua estiveram em niveis adequados. Concluiu-se que, com menores densidades, obtem-se girinos maiores e lotes mais uniformes com melhor taxa de sobrevivencia.

Digestibilidade aparente da energia e nutrientes do farelo de canola pela tilápia do Nilo (Oreochromis niloticus)

This study was carried out to determine the digestible energy and apparent nutrient digestibility of canola meal for Nile tilapia (Oreochromis niloticus). The chromic oxide (0.1%) was used as an inert indicador in the semi-purified diet and faeces were collected by Guelph system. Fish were fed to apparent satiation. The apparent nutrient and energy digestibility of canola meal were: 77.84, 71.99, 86.92, 88.19, 67.16, and 29.86% for dry matter, energy, protein, lipids, calcium and phosphorus, respectively, corresponding to 2969,98 (kcal/kg); 69.97, 32.6, 1.2, 0.41, and 0.28% of, digestible energy, dry matter, protein and lipids and available calcium and phosphorus, respectively. The results obtained in this experiment evidence that Nile tilapia may be able to utilize canola meal eficiently.

Dietas peletizada e extrusada para machos revertidos de tilápias do Nilo (Oreochromis niloticus L.), na fase de terminação

This experiment was carried with the objective of comparing pelletized and extrused diets for reversed Nile tilapias, from 188.9 to 362.4g. One hundred Nile tilapias were, distributed in an entirely randomized design with two treatments and five replications. Temperature and water transparency data were taken every five days. Concerning feed conversion and survival rate there was no difference (P>0.05) between diets pelletized and extrused. The greatest gain and protein efficiency rate (P<0.05) were achieved by extrused diet, as well as the best result of uniformity. Regarding the average cost of ration per kilo gained by fish in each treatment, the least cost (P<0.05) was achieved by pelletized diet. It may be concluded that extrused diet favoured the great gain, however, the least cost of ration per kilo is achieved by pelletized diet.

Exigência de metionina + cistina para alevinos de Tilápia do Nilo (Oreochromis niloticus)

This study was carried out to determine the methionine + cystine requirement for Nile tilapia, fingerlings (2.61 ± 0.14g). A randomized block designs, with six treatments, three replicates and five fish by experimental unit was used. Basal diet was utilized with 28% crude protein and 3173DE kcal kg-1 of digestible energy, supplemented with DL-methionine, resulting in diets with 0.87; 0.95; 1.03; 1.11; 1.19 and 1.27% of methionine + cystine. Diets were fed to satiation during 41 days. No effects (P>0.05) of methionine + cystine levels on survival rate and hepatosomatic index were observed. A quadratic effect (P<0.05) for weight gain was observed, which increased up to 1.22% methionine + cystine in the diet. Feed conversion ratio and protein efficiency ratio increased (P<0.05) up to 1.00% of methionine + cystine. A quadratic effect (P<0.05) of methionine + cystine level on carcass yield was observed, which increased up to 1.13% of methionine + cystine. The concentration of 1.00% methionine + cystine corresponding to 3.54% crude protein, in the presence of 0.54% methionine in the diet, showed the best njperformance.

Nutritional innovations on amino acids supplementation in Nile tilapia diets

The optimal dietary supply of amino acids to tilapia has been studied for many years. Nevertheless, a general agreement on the amino acid requirement for tilapias has not been established. In order to optimize efficiency and reduce surplus nitrogen, values of digestibility of each amino acid of feed must be considered. Due to variations in the amino acid requirement due to new tilapia strains introduction, continuous research on amino acid requirements is necessary to elaborate economical and environmental sustainability diets, also improving fish growth, efficiency and fillet yield. The concept of ideal protein in tilapia diets was introduced more than ten years ago, and new researches have shown the importance of protein and amino acids on fish performance and health, when tilapias are submitted to constant challenging from internal and external factors. Inovacoes sobre o uso de aminoacidos industriais em dietas para a tilapia-do-nilo RESUMO - O suprimento adequado de aminoacidos dieteticos para tilapias tem sido estudado por muitos anos. No entanto, ainda nao foi estabelecida uma concordância geral sobre a exigencia de aminoacidos para tilapias. A fim de otimizar a eficiencia e reduzir o excesso de nitrogenio, as dietas devem ser elaboradas considerando-se os valores de digestibilidade de cada aminoacido dos alimentos. Devido as variacoes nas exigencias de aminoacidos pela introducao novas linhagens de tilapias, a investigacao continua sobre exigencias de aminoacidos e necessaria para a elaboracao de dietas ambiental e economicamente sustentaveis que melhorem tambem o crescimento dos peixes, a eficiencia alimentar e o rendimento de file. O conceito de proteina ideal em dietas de tilapias foi introduzido ha mais de dez anos, e novas pesquisas tem mostrado a importância da proteina e aminoacidos no desempenho e na saude dos peixes submetidos a desafios frente a fatores internos e externos. Palavras-chave: aminoacidos, desempenho, digestibilidade, proteina ideal, peixes, qualidade da carne

Digestible lysine requirement of Nile tilapia fingerlings fed arginine-tolysine-balanced diets

This study was conducted to determine the digestible lysine requirements of Nile tilapia fingerlings. Fish (n = 300; average initial weight = 1.44 g) were distributed 15 300-L aquariums, in a completely randomized design with five treatments and three replicates, and fed extruded diets containing 11.3, 13.7, 16.1, 18.4 or 20.8 g/kg of digestible lysine. The arginine:lysine ratio was maintained at 1.3:1. All fish were fed diets containing 281 g/kg of digestible protein and 3,372 kcal digestible energy/kg, hand-fed until apparent satiation. There was no effect of the dietary lysine levels on survival rate, or protein and ash body rates. With increasing levels of lysine in the diet, a quadratic effect on weight gain, feed conversion, protein efficiency ratio, protein deposition rate, deposition rate of fat, body moisture and body lipids was observed, where the best values of the variables were estimated at 15.96, 16.4, 14.35, 15.21, 15.87, 15.21 and 16.29 g/kg of lysine, respectively. The digestible lysine requirement of Nile tilapia fingerlings is 15.21 g/kg (5.41 g/100 g of digestible protein), in diets balanced for the arginine:lysine ratio.

Digestible methionine + cystine requirement for Nile tilapia from 550 to 700 g

This trial was conducted to determine the dietary digestible methionine + cystine requirement of Nile tilapia (550 to 700 g) based on the ideal protein concept. Six hundred fish were distributed in a completely randomized design with five treatments and four replicates, with 30 fish per experimental unit. The fish were fed diets containing approximately 262 g of digestible protein/kg, 3,040 kcal of digestible energy/kg and 7.90, 9.40, 10.90, 12.40 or 13.90 g of methionine + cystine/kg. The fish were hand-fed three times a day until apparent satiation for 30 days. No effects of dietary methionine + cystine on feed conversion ratio, daily protein deposition, whole body moisture, fillet moisture, crude protein, ether extract and ash, plasmatic HDL and LDL cholesterol were observed. Dietary methionine resulted in a linear increase in whole body protein and linear reduction in lipid deposition rate, hepatosomatic index, whole body ether extract and ash, plasmatic total cholesterol, plasmatic total lipids and plasmatic triglycerides. According to the Linear Response Plateau, the daily weight gain and fillet yield increased up to a level of 9.00 and 9.90 g methionine + cystine/kg of diet, respectively. The digestible methionine + cystine requirement of Nile tilapia is 9.00 g/kg for weight gain and 9.90 g/kg for fillet yield, corresponding to methionine + cystine:lysine ratios of 0.60 and 0.66, respectively.