Tadeu Orlandi Xavier

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.

Extruded snacks with the addition of different fish meals

Tilapia, salmon, tuna and sardine meals were prepared to develop and analyze extruded snacks with residue meal from fish processing. Residue meals were included in five types of corn snacks: control (0% fish meal) and four with 9% tilapia, salmon, tuna and sardine meals. Although moisture, lipids and carbohydrates rates did not differ among the snacks, protein rates increased with the increment of fish meal, reaching 11.85% in the tuna snack. Tuna and sardine snacks had the highest iron levels. The most abundant fatty acids were linoleic, oleic, palmitic, linolenic and stearic acids, with sardine, salmon and tuna snacks presenting the highest values of n-3 series fatty acids. Greater luminosity rate was reported for salmon snack, followed by tilapia, tuna and sardine snacks. The highest sensory acceptance index was verified in tilapia (78.07%) and salmon (72.40%). A 9% addition of residue meals of tilapia, salmon and tuna improved the nutritional value of the snacks.

Addition of different tuna meal levels to pizza dough

O objetivo deste trabalho foi desenvolver massas de pizza com diferentes niveis de inclusao de farinha de atum (Tunnus spp.). Para a producao da farinha de atum, foram utilizados troncos de atum sem nadadeiras, cozidos por uma hora, prensados, moidos e desidratados por 24 horas a 60 °C. Foram elaboradas massas de pizza sem inclusao (0%) ou com inclusao de 5, 10, 15 e 20% de farinha de atum, sendo estas inclusoes calculadas com base na quantidade de farinha de trigo. A farinha de atum e as diferentes massas foram analisadas quanto aos teores de umidade, proteina bruta, lipideos totais, cinzas e carboidratos, alem do valor calorico e do perfil de acidos graxos. Analises microbiologica e sensorial foram realizadas nas massas de pizza. A crescente inclusao de farinha de atum resultou em aumento do teor de proteina bruta (10,89 a 18,94%), de lipideos totais (4,63 a 5,89%) e de cinzas (2,54 a 3,54%) nas massas, sem influenciar no teor de umidade e no valor calorico. A inclusao de farinha de atum aumentou linearmente a quantidade de acidos graxos da serie n-3 nas massas, com aumento de 1,56 para 5,93 g/kg, em 20% de inclusao de farinha de atum. A relacao entre acidos graxos poli-insaturados e saturados da farinha de atum e das massas variou entre 1,21 e 1,85. A analise microbiologica demonstrou que as massas foram produzidas em condicoes adequadas de higiene. Observou-se que a inclusao de 5 a 20% de farinha de atum na massa de pizza nao interferiu significativamente (p>0,05) nos parâmetros de aroma, sabor, impressao global e intencao de compra. Concluiu-se que a inclusao de 5 ate 20% de farinha de atum e eficaz para melhorar o valor nutritivo e o perfil de acidos graxos de massa de pizza.

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