Lilian Carolina Rosa da Silva

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.

Redução da proteína da dieta com base no conceito de proteína ideal para tilápias-do-nilo (Oreochromis niloticus) criadas em tanques-rede

This study was carried out to evaluate the performance of Nile tilapia, cultured in net pens, and fed diets containing 27.0 (control), 25.2, 24.3, and 22.7% of digestible protein. Crystalline amino acids (L-lysine, DL-methionine and L-threonine) were added to keep amino acid levels according to the ideal protein profile and to simulate amino acid levels of the control diet. Fish (34.63±1.19 g) were hand-fed one of the four isoenergetic (3,075 kcal of digestible energy/kg, as fed basis) experimental diets until apparent satiation, three times a day during 90 days. A completely randomized design with four treatments, three replicates and 25 fishes per experimental unit was utilized. No effects of dietary digestible protein levels on weight gain, feed conversion, protein efficiency ratio, empty carcass weight, carcass yield, fillet weight and yield, survival, and hematocrit were observed. It was observed quadratic effect on feed intake and nitrogen excretion, wich increased up to 24.41 and 24.92% of dietary digestible protein, respectively. The reduction of digestible protein levels resulted in a linear increase of nitrogen retention. It was concluded that it is possible to reduce the dietary digestible protein from 27.0 (29.1% of CP) to 24.3% (26.6% of CP) in amino acid supplemented diets (based on ideal protein concept), for juvenile Nile tilapia, cultured in net pens, without adverse effects on growth performance, carcass yield and composition, hematological parameters and cost of diet/kg of fillet gain.

Exigência de fósforo disponível para juvenis de tilápia-do-nilo

Available phosphorus requirement of juvenile Nile tilapia (Oreochromis niloticus) was determined. A total of 352 fishes with initial weight of 0.41 g ± 0.30 g was assigned to a completely block experimental design were used, with four levels of available phosphorus and four replications. Diets with 32.0% CP and 3,050 kcal DE/kg were supplemented with dicalcium phosphate to obtain levels of 0.21; 0.40; 0.56 and 0.71% of available phosphorus in the diets. Diets were handly fed during 120 days. No effects of available phosphorus levels on feed intake, content of protein and ether extract in the carcass and mortality rate were observed. The available phosphorus levels showed a quadratic effect on weight gain, feed:gain ratio, protein efficiency ratio and the calcium percentage in the bones, that were better in levels 0.55, 0.52, 0.52, and 0.60% of available phosphorus, respectively. Data analysis by broken-line regression method indicated adequate deposition of phosphorus in the bone with 0.64% of phosphorus in the diet. The requirement of available phosphorus for juvenile Nile tilapia raised in recirculation tanks is of 0.52%.

Exigência de lisina pela Tilápia do Nilo ( Oreochromis niloticus), na fase de terminação

The present study was carried out to determine the lysine requirement for Nile tilapia (Oreochromis niloticus). Seventy two reversed fish with average weight initial of 117.9 ± 0.67g were for by 50 days with four diets (25% of crude protein and 3090kcal kg-1 of digestible energy) containing different values of inclusion of L-Lysine HCl: 0.1; 0.3; 0.5 and 0.7%, corresponding to rations with 1.13; 1.27; 1.42 and 1.57% of lysine, respectively. Fish were distributed in 12 tanks of 1000-L each, in a completely randomized design with four treatments, three replicates and six fish per experimental unit. No differences were observed in the temperature, pH, dissolved oxygen and electric conductivity of the water in the different treatments. No effects (P>0.05) of lysine inclusion were observed on survival rate, feed conversion, visceral fat, hepatosomatic index and carcass yield. There was no sign of quadratic effect (P<0.05) on weight gain and protein efficiency ratio, estimating the requirements values of 1.42% (5.7% of crude protein or 4.8mg of lysine kcal-1 of digestible energy in diet) and 1.35% of lysine (5.4% of crude protein), respectively. Considering the performance, a requirement value of 1.42% of lysine (5.7% of protein or 4.8 mg of lysine/kcal of digestible energy in diet) was obtained for Nile tilapia, in grow-out phase.

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).

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.

Desempenho e morfometria intestinal de juvenis de tilápia-do-nilo alimentados com dietas suplementadas com L-glutamina e L-glutamato

This work was carried out to evaluate levels of L-glutamine and L-glutamate in diets for Nile tilapia juveniles (0.60 ± 0.1 g). A complete randomized experimental design with four diets and three replicates and 90 fish per experimental unit was used. It was used a control diet with 29% of digestible protein and 2,940 kcal/kg of digestible energy supplemented with L-glutamine and L-glutamate at the proportion of 0, 1, 2 and 3% of diet, during 85 days. It was not observed effect of dietary L-glutamine and L-glutamate on feed intake, food conversion, protein efficiency rate, nitrogen retention efficiency, hepatic somatic index, chemical body composition, blood ammonia and urea. It was observed a linear increase on gain weight and a quadratic effet on villus height when levels of L-glutamine and L-glutamate increased. The addition of L-glutamine and L-glutamate increases the weight gain and intestinal villus height of Nile tilapia.

Ácido linoléico conjugado (CLA) em dietas para tilápia-do-nilo: desempenho produtivo, composição química e perfil de ácidos graxos

The objective of this work was to evaluate the influence of the addition of CLA in the diet on Nile tilapia productive performance, chemical and fatty acids composition. Eighty reversed fish with 109 ± 10 g were used, distributed in eight tanks (0.8 m3 each) in density of ten fishes/tank, during 90 days. It was evaluated the inclusion in the diets of 2% of CLA (Luta-CLA®-BASF, Brazil) with 60% of isomers (cis-9,trans-11 and trans-10,cis-12) and 40% of vehicle (oleic acid and other fatty acids). As diets, a commercial extruded ration with 29% CP and 3000 kcal DE/kg of ration was used. At the end of the experiment all fishes were used for the evaluation of performance, of chemical composition and profile of fatty acids on liver and fillets. No differences for protein efficiency ratio, carcass yield, hepatosomatic index and visceral fat, were observed with the addition of CLA in the diet. The addition of CLA in the diet improved weight gain, feed intake and feed conversion ratio. Fishes fed diets with addition of CLA showed an increase in saturated fatty acids composition, reduction in n-6 fatty acids in the fillets and increase in n-3 fatty acids and total polyunsaturated fatty acids composition in the liver. There was an increase of protein in fillets of tilapia fed with rations enriched with CLA. CLA utilization improve productive performance, affect the fatty acids metabolism and pattern in fillets and liver and increase the body protein of Nile tilapia.

Níveis de teonina em rações para tilápias-do-nilo

This experiment was conducted to determine the dietary threonine requirements for Nile tilapia. The fishes (37.61 ± 1.16 of initial weight) were allotted to a completely randomized design with four treatments, three replicates and 25 fishes per experimental unit. It was used a reference diet with 27% of CP and 3,000 kcal of DE/kg, supplemented with L-threonine, resulting in diets with 0.92, 1.06, 1.21, and 1.35% of total threonine. Synthetic amino acids were added to mantain their profile according to the ideal protein concept. Fishes were fed ad libitum during 110 days. No effects of dietary threonine levels on feed intake, liver weight, hepatic somatic index, carcass yield, fillet yield and fillet water composition (CP and EE) were observed. It was observed linear increase on weight gain, feed:gain ratio, protein efficiency rate, nitrogen retention, carcass weight, fillet weight and ash content in fillet. Considering data of performance, cost/kg of weight gain and cost/kg of fillet weight, the dietary total threonine requirement is of 1.35% [5.51% of digestible protein or 74% of lysine (based on the ideal protein concept)] for Nile tilapia from 38 to 351 g, reared in net pens.