Mathematical modeling for digestible protein in animal feeds for tilapia

The objective of this study was to formulate mathematical models to estimate digestible protein in some animal feeds for tilapia. Literature results of the proximate composition of crude protein, ether extract, and mineral matter, as well as digestible protein obtained in biological assays, were used. The data were subjected to multiple linear stepwise backward regression. Path analysis was performed to measure the direct and indirect effects of each independent variable on the dependent one. To validate the model, the experience used data from independent studies and values obtained from a digestibility trial with juvenile Nile tilapia testing five meat and bone meals, using the Guelph feces collecting system and chromium oxide (III) as an indicator. The obtained model used to estimate digestible protein values (DP) of animal origin is: DP(g kg-1) = -204.15+1.203xCP;R² = 0.953. The path coefficients showed a high direct positive effect (0.900) of crude protein on the digestible protein content. The mineral matter content has an indirect negative effect on protein digestibility (-0.710), reducing the crude protein content and quality

Rendimento e composição química do jundiá Rhamdia voulezi alimentado com vitamina B12

O objetivo deste trabalho foi avaliar a ação da vitamina B12 sobre o rendimento e composição corporal do jundiá R. voulezi. Foram cultivados 900 juvenis com peso médio inicial de 68,51±8,44g, distribuídos em 18 tanques-rede de 5,0 m³, com seis tratamentos e três repetições, durante 360 dias. A vitamina B12 foi adicionada à dieta na proporção de 0; 0,25; 0,5; 1,0; 2,0 e 4,0 mg kg-1 de ração. Considerando machos e fêmeas, houve diferença significativa no índice hepatossomático dos peixes suplementados com 0,5 mg de vitamina B12 kg-1. Quanto ao rendimento corporal com distinção de sexo, foi observado diferença significativa no tronco limpo para os machos suplementados com 0,25 mg de vitamina B12 kg-1. Para a composição química geral da carcaça, observou-se aumento do teor de proteína bruta do grupo suplementado com 0,5 mg kg-1 de vitamina B12. Houve redução dos teores de lipídios da carcaça com suplementação de vitamina B12, em que, os menores valores foram obtidos nos níveis 1,0 e 2,0 mg kg-1, evidenciando os efeitos da vitamina B12 sobre a redução da gordura corporal. O nível que proporciona os melhores resultados de rendimento e composição química da carcaça do jundiá R. voulezi cultivado em tanques-rede é de 1,0 mg de vitamina B12  kg-1 de ração

Performance and body composition of Nile tilapia fed diets supplemented with AminoGut® during sex reversal period

The present study was to evaluate the effects of the commercial product AminoGut® (Ajinomoto, SP), a source of glutamine and glutamate, on performance and body composition of Nile tilapia fingerlings. A study was conducted with 26,000 Gift strain tilapias, with seven days of age during the sex reversal, with initial weight and length of 0.037±0.09 g and 13.28±0.78 mm. The fish were distributed in a completely randomized design with five treatments and four replications, totaling 1,300 fish/tank of 0,5m3 each one. Control diet was used with approximately 500 g/kg of crude protein and 3,840 kcal/ kg of digestible energy. The AminoGut® was added to the control diet at a ratio of 5, 10, 15 and 20g/kg to replace L-alanine. Each diet was provided 10 times per day at intervals of one hour, from 8:00 until 17:00, for 30 days. No effect was observed on weight gain (p>0.05) in fish fed with increasing levels of Aminogut®. However, a positive linear effect (p<0.05) on feed conversion, protein efficiency ratio and survival of the fish supplemented was verified. The inclusion of Aminogut® up to 20 g/kg improves the feed conversion, protein efficiency ratio and survival, parameters of Nile tilapia during sex reversal

Digestible lysine requirement of Nile tilapia from 86 to 227 g fed arginine to lysine balanced diets<br>Exigência de lisina digestível para a tilápia-do-Nilo de 87 a 226 g alimentada com dietas balanceadas para a relação arginina: lisina

This study was conducted out to determine the dietary digestible lysine requirements of Nile tilapia from 87 to 226 g. Fish (n = 170; average initial weight = 86.62 ± 4.89 g) were distributed 15 1000-L cages, in a completely randomized design with five treatments and three replicates, and fed extruded diets containing 0.88; 1.12; 1.36; 1.59 and 1.83% of digestible lysine, balanced to keep the arginine to lysine ratio as 1.43:1. There was no effect of the dietary lysine levels on whole body moisture and ash. By Linear Response Plateau analysis of lysine levels on daily gain, feed conversion, protein efficiency ratio and rate of protein deposition was estimated requirement of 1.31, 1.03, 1.16 and 1.31 % of lysine, respectively. A quadratic effect of lysine levels on whole body fat deposition ratio and whole body ether extract composition were observed, and the lowest values were estimated with 1.16% and 1.43% of dietary lysine, respectively. An increase of the dietary lysine levels resulted in linear increase on the fillet yield. The digestible lysine requirements of Nile tilapia (87 to 226 g) is 1.31%, in diets balanced for arginine to lysine ratio.<p><p>Este estudo foi realizado com o objetivo de determinar a exigência de lisina digestível em dietas para alevinos de tilápia-do-Nilo de 87 a 226 g. Os peixes (n=300; peso inicial médio = 86,62 ± 4,89 g) foram distribuídos em 15 tanques-rede de 1000 L cada, em delineamento inteiramente casualizado com cinco tratamentos e três repetições e alimentados com dietas extrusadas contendo 0,88; 1,12; 1,36; 1,59 e 1,83% de lisina digestível, balanceadas para relação arginina:lisina em 1,43:1. Não foi observado efeito dos níveis de lisina na dieta sobre os teores de umidade e proteína corporal. Pela análise Linear Response Plateau dos níveis de lisina sobre o ganho de peso diário, conversão alimentar, taxa de eficiência proteica e taxa de deposição de proteína, estimou-se exigência de 1,31; 1,03; 1,16 e 1,31% de lisina digestível, respectivamente. Foi observado efeito quadrático dos níveis de lisina sobre a taxa de deposição de gordura e teor de extrato etéreo corporal, em que os menores valores dessas variáveis foram estimados com 1,16% e 1,43% de lisina, respectivamente. Com o incremento nos teores de lisina na dieta ocorreu aumento linear no rendimento de filé e nível de proteína corporal. Concluiu-se que a tilápia-do-Nilo (87 a 226 g) exige 1,31% de lisina digestível, em dietas balanceadas para a relação arginina:lisina

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

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