Mariana Michelato

Exigência de fósforo disponível para tilápia-do-nilo (35 a 100 g)

The objective of this work was to determine the available phosphorus requirement of Nile tilapia. A total of 144 fishes with initial weight 35.33 ± 0,66g LW were distributed to a completely randomized blocks design, with four treatments and three replicates. Diets with 29.0% CP and 2980 kcal/kg DE and four available phosphorus levels (0.25; 0.35; 0.45 e 0.55%) were used. The dicalcium phosphate was used as phosphorus source. The diets were fed to the fishes three times a day to apparent satiation, during 46 days. No significant effect of dietary available phosphorus on hepatosomatic index, survival rate and carcass water and protein contents were observed. The increase of available phosphorus levels in the diet promoted linear increase of average weight gain and phosphorus excretion, and content of ash in carcass and ashes, calcium. There was a quadratic effect of dietary available phosphorus on feed intake, feed conversion ratio and protein efficiency ratio and the best values were obtained with 0.37, 0.48 and 0.48%, respectively. Dietary requirement of available phosphorus for Nile tilapia from 35 to 100 g is 0.48% (0.53% DM).

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.

Conjugated linoleic acid in pacu diets: deposition time, performance and fatty acids profile

Avaliou-se a influencia da adicao (1,2%) de acido linoleico conjugado (CLA) na dieta sobre o desempenho, a deposicao e o perfil de acidos graxos na carne de pacus. Foram utilizados 112 pacus em crescimento (256,19 ± 24,09), distribuidos em delineamento inteiramente casualizado, com dois tratamentos e quatro repeticoes, em oito tanques (1 m3 cada), e alimentados ate a saciedade aparente, tres vezes ao dia, durante 60 dias. Utilizou-se dieta extrusada, com 28% PB e 3.000 kcal ED/kg de racao. A cada duas semanas, foram coletados oito peixes de cada tratamento (dois de cada repeticao) para determinar a composicao de acidos graxos no tempo. Pela analise de Broken-line, a maxima deposicao do cis-9, trans-11, trans-10, cis-12 e do CLA total foi estabelecida com 23, 20 e 21 dias, respectivamente. Nao foram observadas diferencas no desempenho e na composicao quimica do peixe inteiro, do file e do figado. A deposicao de CLA ocorreu em altas concentracoes em todos os tecidos do pacu. O fornecimento de CLA na dieta afetou a composicao de acidos graxos poliinsaturados e monoinsaturados no peixe inteiro, file e figado. A deposicao de CLA em pacus corresponde a ate 3,6% dos lipidios totais no peixe inteiro e no file.

Length-weight relationship and prediction equations of body composition for growing-finishing cage-farmed Nile tilapia

The objective of the present study was to develop models for predicting live weight from the length-weight relationship and body composition of Nile tilapia. A total of 3,000 juvenile fish (initial weight = 28.6±4.16 g and standard length = 13.8±0.16 cm) were distributed into three circular cages (12 m3 each). The fish were hand-fed extruded diets containing 332 g kg-1 of crude protein and 3,230 kcal kg-1 of digestible energy, until apparent satiety, twice daily, for 100 days. Twelve fish were collected from each cage every 20 days for measurements of body weight and length, and proximate composition analysis; statistical analysis was conducted using linear regression. The value of the slope b and the intercept for the length-weight relationship were 3.0604 and 0.0203, respectively. The prediction equations obtained for body moisture (MO), crude protein (CP), crude lipid (CL), and ash against body weight (BW) in g/100 g of fish were as follows: MO = 70.0090 - 0.0071BW; CP = 13.7550 + 0.0037BW; CL = 9.2636 + 0.0057BW; and ash = 4.2392 - 0.0024BW. It is possible to develop equations to predict body weight and composition, which can be used to control the production of Nile tilapia and improve its commercial value.

Length-weight relationships and prediction equations of body composition of farm raised Astyanax aff. Fasciatus (Actinopterygii: Characiformes: Characidae)

This study ascertains the length-weight relationship and predicts body composition equations in cultivated Astyanax aff. fasciatus. A total of 300 fish were distributed in five groups according to body weight: 1.19 ± 0.18, 3.7 ± 0.70, 7.55 ± 0.97, 12.28 ± 2.32 and 22.16 ± 2.64 g. The length-weight relationship was elaborated using linear (yi = b0 + b1xi) or second-order (yi = b0 + b1xi + b1xi2) regression analysis. The value of the b slope in the length-weight relationship was 3.6971 and the intercept was 0.0031. The prediction equations obtained for body moisture, crude protein, crude lipid and ash were, y = 71.680 - 0.404BW, y = 17.140 - 0.095BW, y = 8.432 +0.364BW and y = 3.720 - 0.032BW, respectively, where BW is the body weight of fish (g). The use of prediction equations to describe body composition as a tool to support fish production and commercialization is suggested.

Composição proximal e perfil de ácidos graxos do lambari-do-rabo-vermelho (Astyanax fasciatus) de diferentes classes de peso

This work was carried out to evaluate the proximate composition and fatty acids acid profile of “lambari-do-rabo-vermelho” according to body weight class: I (3.24 - 4.46g); Class II (9.08 - 11.62g); Class III (15.8 - 18.89g) and Class IV (32.25 - 54.64g) with 25 fish each class of to determine the proximate and fatty acids compositions. No significant effects on the fish ash content into fish weight class were observed. Fish from Class I showed highest humidity and lowest whole body lipid levels compared to fish from classes II, III and IV. The highest level of lipid was observed in fish from Class IV and no differences were observed between fish from Classes II, III and IV. Palmitic (16:0) and oleic (18:1 n9) acids were the major saturated and monounsaturated fatty acids, respectively, in the whole body, independently of fish weight class. The total amount of saturated fatty acids was higher (P <0.05) in the fish of Class I, which also showed higher levels of palmitic, linoleic and docohexaenoic acids. Fish from Class II, III and IV showed the highest level of n-3/n-6 ratio compared to fish from Class I, but all class of fish weigh analyzed were shown nutritional value satisfactory for human consumption in terms crude protein, lipids and n-3/n-6 and AGP/AGS ratios.

Mathematical modeling for digestible protein in animal feeds for tilapia

The objective of this study was to formulate a mathematical model to estimate digestible energy in animal feeds for tilapia. Literature results were used of the proximate composition of crude protein, ether extract, mineral matter and gross energy, as well as digestible energy obtained in biological assays. The data were subjected to stepwise backward multiple linear regression. Path analysis was performed to measure the direct and indirect effects of each independent variable on the dependent one. To validate the model, data from independent studies and values obtained from a digestibility trial with juvenile Nile tilapia testing five meat and bone meals (MBM) were used, using the Guelph feces collecting system and chromium oxide (III) as an indicator. The obtained model is described below and cannot estimate digestible energy (DE) of animal origin: 775