Friday, 3 February 2012

Wilds rantsoene


1.       Diere floreer op eentonigheid – Dieselfde Voer ,in dieselfde bak ,elke dag en beskikbaar op dieselfde tyd.(praktise nie altyd haalbaar nie maar probeer dit so naby as moontlik so hou.)

2.       As die troppe redelik groot is probeer altyd genoeg bakke/vreetspasie gee sodat die swak kompeteerders ook by die voer kom . Onthou diere in troppe het altyd ‘n” pecking order” en jy wil nie net sekerediere voer in ‘n trop nie .

3.       Vir optimale produksie  is konstante kondisie die eerste beperking , oorvet diere raak nie sommer dragtig nie en so ook te maer diere . dus diere met ‘n konstante gesonde kondisietelling sal optimaal presteer  en daarom is dit van uiterste belang om al die diere (veral vroulike diere) genoeg kos regdeur die jaar te gee sodat haar kondisie konstant kan bly ( Voedings vlakke sal wysig na gelang van die seisoen )

4.       Kwaliteit ruvoer in droe maande is van kardinale belang , min van die geformuleerde voere is as volledige voer geregistreer en sal dus minder vesel bevat , wat die rissiko daarstel vir suurpens en opblaas as die diere hulle ooreet , Diere moet ook stelselmatig aangepas word op die voer , begin liewer 30 dae vroeer voer as wat jy jou diere siek gaan  voer .

5.       Voordeel van die verpilde voer is dat die diere se voedingstatus verhoog kan word een tot twee maande voor die natuurlike dekseisoen deur met ‘tipiese prikkel voeding te begin , wetenskap het bewys dat diere in toenemende fase van liggaams kondisie makliker dragtig raak .

Unieke samestelling van Wille pille



1.       Ruvoer basis is Lusern ,vir die goeie verteerbaarheid van die rantsoen (help nie jou voer is vol lignien (onverteerbare vesel)en die dier kan niks daarvan benut nie , dit help gewoonlik net om meer humis in die grond te verskaf

2.       Lusern is hoog in versadigede vetsure wat `n bydrae lewer in die energie en proteien behoeftes van die dier .

3.       Verbyvloei proteien tegnologie- die sojaoliekoek wat in die produk is is behandel sodat daar ‘n verhoogde verbyvloei protein  in die rantsoen is wat die volgende eienskappe navore kan bring

·         Verbeterde melkproduksie

·         Verhoogde groei -jong diere

·         Beter horing groei

4.       Voormengsel in die rantsoen bevat die nodige minerale en vitamienes vir optimale produksie, daar word van organiese sink en koper gebruik gemaak wat nodig is vir vrugbaarheid . Daar is ook biotien bygevoeg  vir gesonde en harde hoewe en horings


Thursday, 2 February 2012

Tilapia-ideal protein

Brazilian magazine of Zootecnia
Print ISSN 1516-3598
R. Bras. Zootec. vol.36 in the,3 Viçosa May/June 2007
AQÜICULTURA
Reduction of the protein of the diet on the basis of the ideal protein concept stops tilápias-of - the Nile (Oreochromis niloticus) created in tank-net
Ideal Dietary protein reduction based on protein concept will be Nile Tilapia (Oreochromis niloticus) cultured in net pens
Daniele Botaro I; Wilson Massamitu Furuya II; Lilian Carolina Rosa Silva III; Lilian Dena of Saints IV; Tarcila Souza de Castro Silva V; Vivian Gomes of Saints V
IDoutoranda of the Program of After-graduation in Ambient Biofísica, IBCCF - Federal University of Rio De Janeiro
IIDepartamento de Zootecnia - State University of Maringá, Center of Agrarian Sciences, Maringá-PR
IIIDoutoranda of the Program of After-graduation in Zootecnia - State University of Maringá, Center of Agrarian Sciences, Maringá-PR
IVMestranda of the Program of After-graduation in Zootecnia - State University of Maringá, Center of Agrarian Sciences, Maringá-PR
 VMestranda of the Program of After-graduation in Animal Nutrition of the UNESP-FMVZ - Botucatu/SP


SUMMARY
The performance of tilápias-of was evaluated - Nile (Oreochromis niloticus) created in tank-net and fed with diets I contend 27,0 (control); 25,2; 24,3 and 22.7% of digestible protein. Crystalline amino acids (L-lisina, DL-metionina and L-treonina) had been added to the diet considering the ideal protein concept and simulating the amino acid profile of the diet it has controlled. The fish (34,63±19 g) had been fed manually with isoenergéticas diets (3,075 kcal of energy digestível/kg of diet) until apparent saciedade, three times to the day, during 91 days. A delineation entirely casualizado was used, with four treatments, three repetitions and 25 fish/experimental unit. Effect of the digestible protein levels had not been observed on the profit of weight, the alimentary conversion, the tax of protéica efficiency, the weight of the eviscerada carcass, the income of carcass, the weight and the income of filé, the survival and the hematócrito. It had quadratic effect of the digestible protein levels on the consumption; the biggest value was esteem for the diet contends 24.41% of digestible protein and excreção of nitrogen, in which optimum resulted esteem it was gotten with fish that had received the diet contend 24.92% of PD. With the reduction in the digestible protein levels, linear increase in the nitrogen retention was observed. It is possible to reduce the digestible protein level, of 27 (29.1% of PB) for 24,3% (26.6% of PB), in diets stops tilápias-of - the Nile created in tank-net. This reduction must be made by means of the suplementação of amino acids (on the basis of the ideal protein concept), considering the performance and the cost of dieta/kg profit in filé.
Word-key: amino acids, excreção of nitrogen, ideal protein


ABSTRACT
This study was carried out you 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. Amino Crystalline acids (L-lysine, DL-methionine and L-threonine) were added you keep amino acid levels according you the ideal protein profile and you 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, fed basis) experimental diets until apparent satiation, three 90 teamses day during days. Completely randomized design with four treatments, three replicates and 25 fishes to per experimental unit was utilized. In 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 you the 24,41 and 24,92% of dietary digestible protein, respectively. The reduction of digestible protein levels resulted in linear increase of nitrogen retention. It was concluded that it is possible you reduce the dietary digestible protein from (29,1% 27,0 of CP) you (26,6% the 24,3% of CP) in amino acid supplemented diets (based on ideal protein concept), will be juvenile Nile tilapia, cultured in net pens, without opposites effects on growth performance, carcass yield and composition, hematological parameters and cost of diet/kg of fillet gain.
Key Words: amino acid, ideal protein, nitrogen excretion


Introduction
Tilápia-of - Nile (Oreochromis niloticus) is one of the species most promising for the piscicultura, for the fast growth in intensive system, for the rusticidade and possessing meat with good organolépticas characteristics and filé without thorns intramusculares. The increase in the productivity of this species requires balanced diets, therefore the natural food is not capable to take care of to the requirements of the fish, mainly when created in tank-net and raceways, where the raised biomass for area and the deficiencies or the desbalanços of nutrients can cause losses of productivity and, consequently, minor economic return.
In the diets of the fish, the protein is the item that more influences the production cost. Formulated diets on the basis of the PB can present superior content of amino acids to the demanded one for the animals, that do not possess protein requirement, but of an adequate ratio of amino acids for the formation of muscular protein and other corporal proteins.
The protein requirement for the tilápia has been determined for diverse authors. Pezzato et al. (1986) and Silva et al. (1989), in experiments with alevinos of tilápia-of - the Nile, they had found requirements of 28 and 34% of PB, respectively. Al Hafedh (1999), evaluating different protein levels in four phases of growth of this species, had determined requirement of 30% of PB for these fish in the adult phase. Furuya et al. (2000) and El-Saidy & Gaber (2005) had evidenced requirement of 32 and 25% of PB, respectively, for youthful alevinos and of this species.
With the intention to reduce the protein content in diets for fish, nutritionists have searched alternative protein sources and/or the suplementação of amino acids in the synthetic form. The results gotten with synthetic amino acids seem to be narrowly related to used foods, its levels of inclusion and the nutricional value of its amino acids (Sadiku & Jauncey, 1995). Thus, the synthetic amino acids must be used for attainment of diets with adjusted ratio of amino acids, of form to maximize the use of the protein of the diet.
In formulated diets on the basis of the protein of the soy bran, the improvement in the performance only occurs when the lisina is supplemented together with other essential amino acids, as observed in tilápias-of - the Nile for Odum & Ejike (1991) and Furuya et al. (2004a); in salmon-of - Atlantic (Salmo to salar) for Olli et al. (1995) and Berge et al. (2002); e in the trout rainbow (Oncorhynchus mykiss) for Davies & Morris (1997) and Yamamoto et al. (2005).
The formularization of diets with lesser protéico level by means of the suplementação of synthetic amino acids makes possible the formularization of diets with values next to the requirements to the fish. The relation between amino acids is basic for the best efficiency of use of the dietary protein.
The ideal protein concept praises the accurate amino acid rocking, using the lisina as amino acid reference and establishing its ratio in relation to too much essential amino acids, of form if to get an ideal amino acid profile that takes care of to the requirements of maintenance and production of the fish. The application of this concept can be adapted to a variety of situations, therefore despite the absolute amino acid requirements can move for diverse reasons, the ratios practically remain steady.
The use of the ideal protein concept can reduce the protein content in the diets, the costs of production and the excreção of nitrogen for the fish, one of the nutrients most pollutant in the aquatic way, mainly in the intensive creations.
This work was carried through with the objective to evaluate the reduction of the protein level in diets stops tilápias-of - the created Nile in tank-net, by means of the application of the ideal protein concept, on the basis of the performance, in the hematológicas characteristics and the economic analysis.

Material and Methods
The experiment was carried through by means of the State University of Maringá, in the Hikari mansion, Paiçandu - PR, the period of January the April of 2004.
4,000 alevinos approximately reverted, with alive weight of 0,5±0,1 g, originated of the Piscicultura Araucária Belmonte, Rolândia-PR, had been distributed in three hapas of nylon (mesh of 2 mm), with useful unitary volume of 6 m3, during two months, where they had been fed with farelada commercial diet, with 32% of PB.
Three hundred fish with initial weight of 34,63±1,19 g had been selected manually in accordance with the weight and distributed in 12 tank-net constructed with mesh of 12 mm (wire multifilament 210/24) with 1,2 x 1,0 2,0 x m and 2,0 unitary useful volume of m3. The tanks had been covered with polyethylene net for protection against birds.
Four diets (Table 1) formulated with different níves of digestible protein had been evaluated: 27,0 = diet has controlled with 27,0% of digestible protein, supplemented with amino acids in order to present the lisina relation/essential amino acids (metionina, metionina + cistina and treonina) determined by Santiago & Lovell (1988) for the tilápias; 25,2 = diet with 25,2% of digestible protein (reduction of 5% in the digestible protein content), with same amount and ratio of amino acids of the diet has controlled; 24,3 = diet with 24,3% of digestible protein (reduction of 10% in the digestible protein content), with same amount and ratio of amino acids of the diet has controlled; 22,7 = diet with 22,7% of digestible protein (reduction of 15% in the digestible protein content), with same amount and ratio of amino acids of the diet has controlled. The diets had been balanced in accordance with the values of protein and digestible amino acids determined by Furuya et al. (2001).


ll the ingredients had been worn out until equal or inferior diameter 0,50 mm. The diets had been granulated (diameter of 4 mm) by means of extrusor in the Experimental Farm of Iguatemi - FEI and dehydrated in greenhouse of ventilation forced 50ºC during 8 hours. The total daily ration was distributed three times/day, to the 8, 12 and 18h, by means of manual arraçoamento until apparent saciedade, when more capture and regurgitação of granules for the fish had not been observed.
All the fish had been weighed in digital scale (0.01 g) at the beginning and to the end of the experiment for determination of the profit of weight, the alimentary conversion and the taxes of protéica efficiency and survival. After pesagem, five fish of each experimental unit had been returned to the respective tanks for posterior hematológica analysis. The too much fish had been conditioned in isothermal box with ice and eviscerados for analyses of the characteristics of carcass (weight of the eviscerada carcass, weight of filés and income of filé) and of the hepatossomático index.
The carcass income was calculated as the reason enters the weight of the eviscerada carcass and 24-hour the alive weight after jejum, while the income of filés corresponded to the reason enters the weight of filés and the alive weight of the animal. The hepatossomático index was determined as the reason enters the weight of the liver and the alive weight of the fish.
For the hematológicas analyses, five fish had been used/repetition to the end of the experimental period. The fish had been anestesiados (benzocaína, 1 g/15 L of water) e, after complete desensitization, were carried through collection of blood for punção of the vein volume with syringe of 3 mL bathed with anticoagulant EDTA 3%. The hemoglobina concentration was determined by the method of the cianometahemoglobina, having used itself commercial kit Hemoglobina Analisa Diagnóstica®, for colorimétrica determination in espectrofotômetro of atomic absorption. The hematócrito was gotten by the method of the microhematócrito. The above-mentioned 0 variable had been evaluated using the described techniques for Jain (1986). The samples of blood had been centrifugadas the 3,000 rpm, during five minutes, for reading in table of % of hematócrito. The analyses had been carried through in the Laboratory of Nutrition of Animal of the Department of Zootecnia of the State University of Maringá.
To each four days, had been taken the measures of temperature (8 and 16h), pH and dissolved oxygen (mg/L) of the water of the tank. The data had been gotten using portable digital kit.
For determination of the digestibilidade coefficients, 15 tilápias-of - the Nile of the lot kept in hapas in the same tank-net had been used, with average weight of 132,5±13,3 g. The tilápias had been kept in two fibre glass aquariums, with useful volume of 180 L for the excrement collection.
The system was kept under constant aeration by means of porous rock connected a central puffer, to keep the oxygen enters 4 the 6 mg/L. The temperature of the water was kept between 25 and 27ºC. These parameters had been surveyed daily, to the 8 and 17h, in portable digital oximeter for reading of the dissolved oxygen and the temperature.
The water renewal of the aquariums of excrement collection was made daily (8h30 and 17h30) using it water proceeding from a 1.000 reservoir of L with water kept in the same conditions of the aquariums of digestibilidade. The fish had been arraçoados daily of the 7 to 9h and the 13 to 17h, manually, until apparent saciedade.
For determination of the CDA, the diets used in the performance experiment worn out and had been added of 0,1% of chromic oxide (Cr2O3) as indicating, being peletizadas in manual mill and dehydrated in greenhouse of forced ventilation 50ºC, as recommended for Pezzato et al. (2002).
Excrement collection was carried through daily to the the 8 and 17h, during five days, to form one pool of samples of each aquarium, that was considered repetition. For the diet exchange, an interval of five days for adaptation was established. The collected material was dehydrated in greenhouse of forced ventilation (55ºC, during 48 hours), being triturated in mill knife, identified and stored in coolant for posterior analysis.
The coefficients of digestibilidade of energy and PB of the diets had been determined in accordance with the expression proposal for Nose (1960).
The nitrogen retention was calculated in accordance with the expression:

where: ERN = efficiency of nitrogen retention (%); Nf = final nitrogen (%); Pf = final weight (g); Ni = initial nitrogen (%); Pi = initial weight (g); Nc = consumed nitrogen (g).
The excreção of fecal nitrogen was determined according to expression:
where: Ne = nutrient excretado (kg/t of fish); Nc = nutrient consumed (kg); CDAn = coefficient of apparent digestibilidade of the nutrient (%); GP = weight profit (kg).
For determination of the excreção of the N, the PB of the diet was converted into N and the value of PB of the diet, divided for 6,25.
The analyses chemistry-bromatológicas of the diets, the carcasses and excrements had been carried through in the Laboratory of Food Analysis of the Department of Zootecnia of the State University of Maringá - UEM, as described methodology for Silva & Queiroz (2002).
The data had been submitted to the analyses of variance and polynomial regression, by means of program SAEG - Systems of Statistical and Genetic Analyses (Euclydes, 1983).

Results and Quarrel
The average values gotten for the temperature and the dissolved oxygen of the water of the tank-net had been 28,55±1,72ºC and 5,72±1,09 mg/L, respectively. The parameters had inside remained of the band recommended for Popma & Green (1990) for adjusted performance of tilápias.
In Table 2 the average values of performance of tilápias-of meet - Nile created in tank-net fed with diets I contend different digestible protein levels.


It did not have effect of the reduction of the digestible protein levels on the profit of weight, the alimentary conversion, the tax of protéica efficiency, the weight of the eviscerada carcass, the income of carcass and the weight and income of filé. Mortality during the experimental period was not observed.
The adequate suplementação of amino acids made possible the reduction of the digestible protein content of the diets and it did not affect the profit of weight of the fish, indicating that the adequate amino acid profile was capable to take care of to the requirement of this species. The fish fed with the diet I contend 25,2 and 24.3% of digestible protein had gotten increase of 10,13 and 6,51% in the weight profit, respectively, in relation to those fed with the diet have controlled. It is standed out that, with the use of the diet with lesser value of digestible protein, the weight profit was similar to the profit of the fish fed with the diet has controlled (27% PD).
Kim (1997), in study carried through with the trout rainbow, evaluated diets with 10, 15, 20, 25 and 35% of PB and observed linear increase (P<0,05) in the profit of weight of the fish fed with the diet contends 25% of PB supplemented with arginine and synthetic metionina. In experiment with the same species, Cheng et al. (2003) they had used protein source of supplemented vegetal origin with amino acids and had observed that the fish fed with the diet with 37% of PB supplemented with synthetic amino acids had presented greater tax of growth in comparison to those fed with diet contend 42% of PB and same values of lisina, metionina, treonina and triptofano. These authors had told despite the diet with bigger level of lisina (1.8%) promoted greater crescimentos of the fish.
The gotten data of alimentary conversion in this study differ from the described ones for Webb & Gatlin (2003), when evaluating levels of 35 and 45% of PB and protein forms (unbroken and supplemented with amino acids) for “red drum” (Sciacrops ocellatus). Divergem still of the results gotten for Berge et al. (2002), in study with salmon-of - the Atlantic one, in which they had evaluated the requirements of lisina and arginine and had noticed improvement in the alimentary conversion of the fish fed with the diet supplemented with synthetic amino acid.
With the reduction in the digestible protein levels, quadratic effect (P<0,05) of the digestible protein level was observed in the consumption, being esteem value of 24,41% of PD for the biggest food consumption (Figure 1).


Yamamoto et al. (2005) they had observed reduction in the consumption in experiment with trout rainbow fed with diets with lesser protéico value. In this study, the biggest consumption was related to the biggest profit of weight, therefore the alimentary conversion practically remained constant in the fish fed with the diets with 27; 25,2 and 24.3% of PD.
Effect of the treatments on the tax of protéica efficiency was not observed. On the other hand, it had linear increase (P<0,05) of the retention of nitrogen to the measure that if reduced the digestible protein content (Figure 2).


The amino acid rocking is important for the maximum exploitation of the protein for the fish. The results of nitrogen retention in this study differ from gotten for Yamada et al. (1981), Cowey & Walton (1989) and Schumacher et al. (1997), that they had questioned the efficiency of use of synthetic amino acids for the fish, the fast rise of synthetic amino acids in the plasmáticos levels and for the losses for catabolismo (Plakas & Katayama, 1981; You wall et al., 1985).
Another factor that can influence the use of synthetic amino acids for the fish is related to the high leaching tax, as observed by Zarate & Lovell (1997), that they had after evidenced leaching of 13% of the synthetic lisina of the diet 15 seconds the contact with the water, while only 2% of on lisina to the protein were leached. In this research, bigger frequency of arraçoamento was adopted (3 times/day) to prevent the fast rise in the plasmáticos levels of lisina, metionina and treonina and to increase the efficiency of use of the protein. The same it was observed by Tantikitti & March (1995) and Berge et al. (2002), respectively, in works carried through with the trout rainbow and the one salmon-of - the Atlantic one.
The relations energy: protein and lisina: arginine important for is adjusted use of amino acids. In this study, the best ones resulted of performance had been gotten with the diets contend relation digestible energy: digestible protein of 122:1 and 127:1 and digestible lisina relation: digestible arginine of 0,72:1 and 0,77:1, with the diets I contend 25,2 and 24.3% of PD, respectively.
Kaushik et al. (1988), in study carried through with trout rainbow, they had told that the increase in the content of arginine in the diet increased the digestibilidade of this amino acid and diminished the digestibilidade of the lisina, indicating that it has competition enters these amino acids for absorption in the thin intestine. Berge et al. (2002), in study carried through with salmon-of - Atlantic, they had observed that the growth and the conversion had improved in the fish fed with diets contend limitantes levels of lisina and high levels of arginine. However, in the diets with limitantes levels of arginine and high levels of lisina, improvement in the growth of the fish was not observed. In this study, in all the diets, the arginine levels had been remained above of the described requirements for the NRC (1993) for the tilápias.
Quadratic effect (P<0,05) of the digestible protein levels was verified in the excreção of fecal nitrogen, being esteem the value of 24,93% of PD for the biggest excreção of fecal nitrogen (Figure 3).


In experiment with carp-greater-of - indian (rohita Labeo), Chakraborty & Chakraborty (1998) had observed increase in the excreção of ammonia with the increase of the protein ingested for these fish. Engin & the Carter (2001), in study with youthful of conger-eel (Anguilla australis), had observed increase of the tax of excreção of ammonia with higher protein levels in the diet. The results gotten in this experiment had confirmed the joined ones for Webb & Gatlin (2003), that they had observed reduction in the excreção of ammonia in “red drum” fed with diets with lesser protein text.
Viola & Lahan (1991) had observed minor excreção of nitrogen for the fed common carp with diet contend 25% of PB in comparison to a diet with 30% of PB. The excreção was still lesser in the fish fed with the diet with 25% of PB supplemented with lisina and metionina. These results are in accordance with found for Rodehutscord et al. (1994), in study carried through with trout rainbow. These authors had observed to be possible to reduce in 16% the excreção of nitrogen in supplemented diets contend glúten of maize and with synthetic amino acids.
Cheng et al. (2003), in study with trout rainbow, they had on the basis of observed that the diet with 37% of PB (vegetal source) resulted in lesser total ammoniac nitrogen discharge for the fish in relation to that one with same protein content, formulated the fish flour. These authors had observed despite, in diets I contend vegetal protein source and supplemented with synthetic amino acids, the excreção of nitrogen was reduced in 26% in comparison to the excreção observed with the diet contends fish flour.
In this study, he did not have effect of the digestible protein levels on the hematócrito and tax of hemoglobina (Table 3). To the exception of the value of hemoglobina found in the fish fed with the diet I contend 22.7% of PD, the hematócrito data and hemoglobina in this study had been superior to the averages of the described values for Tavares-Day & Moraes (2004), of 28,58% and 7,97 g/dL, respectively, in works carried through with tilápias-of - the Nile in captivity.


The protein content of the diets did not influence the weight and income of carcass and filé. However, in the fish fed with the diet I contend 25.2% of PD had gotten bigger incomes of carcass (1.6%) and of filé (1.43%) in relation to those fed with the diet it has controlled. The biggest incomes of carcass and filé had been probably related to the suplementação of lisina, metionina and treonina, used for the muscular fabric synthesis, as explained for Bailey (1989).
As demonstrated in Table 4, it did not have effect of the digestible protein levels on the chemical composition of the carcass. The results of the works carried through with diets I contend different protein levels do not prove effect on the composition of the carcass of the fish, in contrast to when the protein it was evaluated together with energy levels, as observed for Lee & Kim (2001), Allan & Booth (2004) and Bechara et al. (2005), in studies carried through with youthful of salmon “masu”, “to silver perch” and pacu, respectively.


The fat deposition narrowly is related to the amino acid balancing and the relation energy/protein of the diet. However, the weight of the fish must be considered, therefore it expects that those of bigger weight present greater content of corporal fat. In this study, despite the fish fed with the diet I contend 25.2% of PD have presented the biggest final weight, these fish had had minor percentage of fat in filés.
In Table 5 the average values of cost in diet for kilo of weight profit and the cost of the diet for kilo of profit in filé of tilápias-of meet - Nile fed with diets I contend different digestible protein levels created in tank-net. The reduction of the digestible protein content did not influence custo/kg of weight profit and custo/kg of profit in filé.


The increase in the suplementação of synthetic amino acids resulted in rise in the cost of the kilogram of the diet. On the other hand, when considered the cost in diet for kilogram of weight profit and the cost in diet for kilogram of profit of weight in filés, the relation cost/benefit practically remained constant, to the exception of custo/kg profit in filé gotten for the fish fed with the diet contends 22.7%. In practical terms, it is possible to consider that the reduction in the time of abates for the attainment of fish with bigger weight and greater carcass income certainly results in bigger economic benefit to the producer.
It proved possibility to reduce the value of digestible protein of the diet of tilápias of 27 for 24,3% of PD, without damages to the growth, the use of the protein of the diet, to the income and to the composition of the carcass, without causing anemia to the fish and modifying the cost of dieta/kg of I earn of alive weight and in filés. Similar results had been observed by Cheng et al. (2003) and Yamamoto et al. (2005) in studies carried through with the trout rainbows, that had made possible the reduction of 42 for 37% of PB and 45 for 31% of PB, respectively, without damages to the performance. Moreover, these authors had verified reduction in the excreção of ammoniac nitrogen for the fish fed with the diet contend lesser protein text.
The reduction of the protein text in the diets of the fish is important to diminish the cost with feeding. Moreover, it diminishes excreção of nitrogen in water, what it assists in the sustainable production of fish, mainly when in conditions of high densities, when the supply is necessary, exclusively, of the balanced diets.
The results gotten in this study had proven to be possible to elaborate balanced diets with reduction of 10% in the digestible protein content stop tilápias-of - the Nile. These results had been gotten with the supply of diets supplemented with amino acids (on the basis of the ideal protein concept), with values of energy, digestible protein and amino acids and available match.

Conclusions
It is possible to reduce the digestible protein text of 27 (29.1% of rude protein) for 24,3% (26.6% of rude protein) in diets stops tilápias-of - the Nile created in tank-net. This reduction can be gotten by means of the suplementação of amino acids (on the basis of the ideal protein concept), considering the performance of the fish and the economic analysis of the production system.

Cited literature
AL-HAFEDH, Y.S. Effects of dietary protein on growth and body composition of Nile tilapia, Oreochromis niloticus. Aquaculture Research, v.30, p.385-393, 1999.
        [Try Similar Google] []
ALLAN, G.L. ; BOOTH, M.A. The effects of dietary digestible protein and digestible energy content of protein retention efficiency of juvenile to silver perch (Bidyanus bidyanus). Aquaculture, v.35, p.970-980, 2004.
        [Try Similar Google] []
BAILEY, A.J. Molecular and to fiber structure of collagen. In: Bailey, A.J. ; LIGHT, N.D. (Eds.) Connective tissue in meat and meals products. London: Elsevier, 1989. p.35-48.
        [Try Similar Google] []
BECHARA, J.A. ; ROUX, J.P. ; DIAZ, F.J.R et al. The effect of dietary protein level on pond to water quality and feed utilization efficiency of pacu Piaractus mesopotamicus. Aquaculture Research, v.36, p.546-553, 2005.
        [Try Similar Google] []
BERGE, G.E. ; SUEIER, H.; LIED, E. Effects of feeding Atlantic salmon (Salmo to salar) imbalanced levels of lysine and arginine. Aquaculture Nutrition, v.8, p.239-248, 2002.
        [Try Similar Google] []
CHAKRABORTY, S.C. ; CHAKRABORTY, S. ammonia Effect of dietary protein level on excretion of in Indian major carp (rohita Labeo), fingerlings. Aquaculture Nutrition, v.4, p.47-51, 1998.
        [Try Similar Google] []
CHENG, Z.J. ; HARDY, R.W. ; USRY, J.L. Plant protein ingredients with lysine supplementation reduce dietary protein level in rainbow trout (Oncorhynchus mykiss) diets, and reduce ammonia nitrogen and soluble phosphorus excretion. Aquaculture, v.218, p.553-565, 2003.
        [Try Similar Google] []
COWEY, C.B. ; WALTON, M.J. Intermediary metabolism. In: HALVER, J.E. (Ed.) Fish nutrition. 2.ed. San Diego: Academic Press, 1989. p.259-329.
        [Try Similar Google] []
Davies, S.J. ; Morris, P.C. Amino Influence of multiple acids supplementation on the performance of rainbow trout, Oncorhynchus mykiss (Walbaum), fed soya based diets. Aquaculture Research, v.28, p.65-74, 1997.
        [Try Similar Google] []
EL-SAYDI, D.M.S.D. ; GABER, M.M.A. Effect of dietary protein levels and feeding rates on growth performance, production traits and body composition of Nile tilapia (Oreochromis niloticus), cultured in concrete tanks. Aquaculture Research, v.36, p.163-171, 2005.
        [Try Similar Google] []
ENGIN, K.; CARTER, C.G. Urea Ammonia and excretion rates of juveniles Australian shorts-finned eel (Anguilla australis australis) influenced by dietary protein level. Aquaculture, v.194, p.123-136, 2001.
        [Try Similar Google] []
EUCLYDES, R.F. Manual of use of program SAEG (System for analyses statistics and genetics). Viçosa, MG: Federal university of Viçosa, 1983. 59p.
        [Try Similar Google] []
FURUYA, W.M. ; HAYASHI, C.; FURUYA, V.R.B et al. Protein requirement for reverted alevino of tilápia of the Nile (Oreochromis niloticus). Brazilian magazine of Zootecnia, v.29, n.6, p.1912-1917, 2000.
        [Try Similar Google] []
FURUYA, W.M. ; PEZZATO, L.E. ; MIRANDA, E.C et al. Coefficients of digestibilidade and values of digestible amino acids of some ingredients for the tilápia of the Nile (Oreochromis niloticus). Brazilian magazine of Zootecnia, v.30, n.4, p.1125-1131, 2001.
        [Try Similar Google] []
FURUYA, W.M. ; SILVA, L.C.R. ; SNOWS, P.R et al. Requirement of metionina+cistina for alevinos of tilápia of the Nile, Oreochromis niloticus. Agricultural science, v.34, n.6, p.1933-1937, 2004a.
        [Try Similar Google] []
FURUYA, W.M. ; BOTARO, D.; SNOWS, P.R. Requirement of lisina for the tilápia of the Nile (Oreochromis niloticus) in the termination phase. Agricultural science, v.34, n.6, p.1933-1937, 2004b.
        [Try Similar Google] []
JAIN, N.C. Schalm's veterinary haematology. 4.ed. Philadelphia: Lea & Febiger, 1986. 1221p.
        [Try Similar Google] []
JAUNCEY, K.; Ross, B. guide you the tilapia feed and feeding. Scotland: University of Stirling, 1982. 111p.
        [Try Similar Google] []
KAUSHIK, S.J.; FAUCONNEAU, B.; TERRIER, L. et al. Arginine requirement and status assessed by different biochemical indices in rainbow trout Salmo gairdneri. Aquaculture, v.70, p.75-95, 1988.
        [ Try Google ]        [ Similar ]
KIM, K-IL. Re-evaluation of protein and amino acid requirements of rainbow trout (Oncorhynchus mykiss). Aquaculture, v.151, p.3-7, 1997.
        [ Try Google ]        [ Similar ]
LEE, S-M.; KIM, K-D. Effects of dietary protein and energy levels on the growth, protein utilizaion and body composition of juvenile masu salmon (Oncorhynchus masou). Aquaculture Research, v.32, p.39-45, 2001.
        [ Try Google ]        [ Similar ]
MURAI, T.; AKIYAMA, T.; WATANABE, T. et al. Effects of dietary protein and lipids levels on performance and carcass composition of fingerlings carp (Cyprinus carpo). Bulletin of the Japanese Society of Scientific Fisheries, v.54, p.605-608, 1985.
        [ Try Google ]        [ Similar ]
NATIONAL RESEARCH COUNCIL - NRC Nutrient requirements of warmwater fishes and shellfishes. Washington, D.C.: National Academy Press, 1993. 102p.
        [ Try Google ]        [ Similar ]
Nose, T. On the digestion of food protein by gold-fish (Carassius auratus) L.) and rainbow trout (Salmo irideus G.). Bulletin Freshwater Fish Research Laboratory, v.10, p.11-22, 1960.
        [ Try Google ]        [ Similar ]
ODUM, O.; EJIKE, C. Aspects of amino acid utilization in the cichlid (Oreochromis niloticus). Acta Hidrobiology, v.33, p.345-352, 1991.
        [ Try Google ]        [ Similar ]
OLLI, J.; KROGDAHL, A. Alcohol soluble components of soybean seem to reduce fat digestibility in fish-meal-based diets for Atlantic salmon (Salmo salar). Aquaculture Research, v.26, p.831-835, 1995.
        [ Try Google ]        [ Similar ]
PEZZATO, L.E.; PACKER. I.V.; PEZZATO, A.C. et al. Efeito de níveis de proteína sobre o crescimento da tilápia do Nilo (Oreochromis niloticus), submetida a reversão sexual. In: SIMPÓSIO BRASILEIRO DE AQUICULTURA, 5., 1986, Cuiabá. Anais... Cuiabá: 1986, p.70-71.
        [ Try Google ]        [ Similar ]
PEZZATO, L.E.; MIRANDA, E.C.; BARROS, M.M. et al. Digestibilidade aparente de ingredientes pela tilápia do Nilo (Oreochromis niloticus). Revista Brasileira de Zootecnia, v.31, n.4, p.1595-1604, 2002.
        [ Try Google ]        [ Similar ]
PLAKAS, S.M.; KATAYAMA, T. Apparent digestibilities of amino acids from three regions of the gastrointestinal tract of carp (Cyprinus carpo) after ingestion of a protein and corresponding free amino acid diet. Aquaculture, v.24, p.309-314, 1981.
        [ Try Google ]        [ Similar ]
POPMA, T.J.; GREEN, B.W. Sex reversal of tilapia in earthen ponds. Aquaculture production manual. Alabama: Alburn University, Alabama Research and Development, 1990. 15p. (Series 35).
        [ Try Google ]        [ Similar ]
RODEHUTSCORD, M.; BORCHERT, F.; GREGUS, Z. et al. Availability and utilization of free lysine in rainbow trout (Oncorhynchus mykiss). 2. Comparison of L-lysine -HCl and L-lysine sulphate. Aquaculture, v.187, p.177-183, 1994.
        [ Try Google ]        [ Similar ]
SADIKU, S.O.E.; JAUNCEY, K. Digestibility, apparent amino acid availability and waste generation potential of soybean flour: poultry meat blend based diets for tilapia, Oreochromis niloticus (L), fingerling. Aquacutlure Research, v.26, p.651-657, 1995.
        [ Try Google ]        [ Similar ]
SANTIAGO, C.B.; LOVELL, R.T. Amino acid requirements for growth of Nile tilapia. Journal of Nutrition, v.118, p.1540-1546, 1988.
        [ Try Google ]        [ Similar ]
SILVA, D.J; QUEIROZ, A.C. Análise de alimentos (métodos químicos e biológicos). 3.ed. Viçosa, MG: Universidade Federal de Viçosa, 2002. 235p.
        [ Try Google ]        [ Similar ]
SILVA, S.S.; GUNASEKARA, R.M.; ATAPATU, D. The dietary protein requirements of young tilapia and an evaluation of the least cost of dietary protein levels. Aquaculture, v.80, p.271-284, 1989.
        [ Try Google ]        [ Similar ]
SCHUHMACHER, A.; WAX, C.; GROPP, J.M. Plasma amino acids in rainbow trout (Oncorhynchus mykiss) fed intact protein or a crystalline amino acid diet. Aquaculture, v.151, p.15-28, 1997.
        [ Try Google ]        [ Similar ]
TANTIKITTI, C.; MARCH, B.E. Dynamics of plasma free amino acids in rainbow trout (Oncorhynchus mykiss) under variety of dietary conditions. Fish Physiology & Biochemistry, v.14, p.179-194, 1995.
        [ Try Google ]        [ Similar ]
TAVARES-DIAS, M.; MOURA, F.R.M. Hematologia de peixes teleósteos. 1.ed. Ribeirão Preto: 2004. 144p.
        [ Try Google ]        [ Similar ]
VIOLA, S.; LAHAN, E. Effects of lisyne supplementation in practical dcarp feeds on total protein sparing and reduction of pollution. The Israeli Journal of Aquaculture, v.43, p.112-1128, 1991.
        [ Try Google ]        [ Similar ]
WEBB, K.A.; GATLIN, D.M. Effects of dietary protein level and form on production characteristics and ammonia excretion of red drum Sciaenopss ocellatus. Aquaculture, v.225, p.17-26, 2003.
        [ Try Google ]        [ Similar ]
YAMAMOTO, T.; SUGITA, T.; FURUITA, H. et al. Plasma amino acid changes in rainbow trout force-fed casein and corresponding amino acid mixture. Bulletin of Japanese Society of Scientific Fisheries, v.47, p.1035-1040, 1981.
        [ Try Google ]        [ Similar ]
YAMAMOTO, T.; SUGITA, T.; FURUITA, H. Essential amino acid supplementation to fish meal-based diets with low protein to energy ratios improves the protein utilization in juvenile rainbow trout (O. mykiss). Aquaculture, 2005 (in press).
        [ Try Google ]        [ Similar ]
ZARATE, D.D.; LOVELL, R.T. Free lysine (L-lysine.HCl) is utilized for growth less efficiently than protein-bound lysine (soybean meal) in practical diets by young channel catfish (Ictalurus punctatus). Aquaculture, v.159, p.87-100, 1997.
        [ Try Google ]        [ Similar ]

Recebido: 25/10/05
Aprovado: 07/12/06
Correspondências devem ser enviadas para: danibot13@biof.ufrj.br