O estudo foi realizado com o objetivo de verificar quais medidas e razões morfométricas estão mais diretamente relacionadas com os rendimentos corporais da tilápia do Nilo, Oreochromis niloticus, em duas classes de peso. Foram analisados os dados de 257 exemplares de tilápia divididos em duas categorias de peso: p1 = 400 a 599 g e p2 = 600 a 900 g. As medidas morfométricas comprimento padrão (CP), comprimento da cabeça (CC), altura do corpo (AC) e largura do corpo (LC), e as razões entre estas medidas (CC / CP, AC / CP, LC / CP, LC / CC, LC / AC, CC / AC) foram avaliadas. Os rendimentos corporais calculados foram: carcaça (RCAR), filé (RFILE) e cabeça (RCAB). Os dados foram inicialmente submetidos ao procedimento 'stepwise' para eliminar os problemas de multicolinearidade entre as variáveis morfométricas, em seguida, as correlações entre as variáveis dependentes (rendimentos corporais) e as variáveis independentes (medidas e razões morfométrica) foram calculados. Posteriormente estas correlações foram desdobradas em efeitos diretos e indiretos por meio de análise de trilha e as contribuições diretas e indiretas de cada variável foram quantificadas percentualmente. A razão morfométrica LC / CC, para ambas as classes de peso, foi a variável mais altamente correlacionada e com o maior efeito direto sobre RFILE e RCAB, mostrando ser a variável morfométrica estudada mais importante para determinação das características de carcaça da tilápia.

The study was carried out with the objective of verifying which measures and morphometric ratios are more directly related to the body yield of Nile tilapia, Oreochromis niloticus, in two weight classes. Data were analyzed from 257 specimens of tilapia divided into two weight classes: p1 = 400 to 599 g and p2 = 600 to 900 g. The morphometric measurements standard length (SL), head length (HL), body height (BH) and body width (BW), and the ratios of these measures (HL / SL, BH / SL, BW / SL, HL / BH, BW / BH, BW / HL) were evaluated. The following body yields were calculated: carcass (RCAR), fillet (RFILE) and head (RCAB). The data were initially submitted to the "stepwise" procedure to eliminate problems of multicollinearity among the morphometric variables, then the correlations between the dependent variables (body yield) and the independent variables (measured and morphometric relationships) were calculated. Later, these correlations were divided into direct and indirect effects through path analysis, and the direct and indirect contributions of each variable measured in percentage terms. The morphometric ratio BW/HL, for both weight classes, was the variable most highly correlated and with the highest direct effect on RFILE and RCAB, showing to be the most important morphometric variable studied for tilapia carcass trait determination.

O objetivo deste trabalho foi determinar a densidade de estocagem de matrinxã (Brycon orthotaenia) em tanques-rede, considerando o desempenho produtivo. Foram utilizados 5.280 juvenis de Brycon orthotaenia com peso inicial de 115,2g±5,7, os quais foram distribuídos em 16 tanques-rede de 4³m nas densidades de 45, 70, 95 e 120 peixes m-3 em quatro repetições. Os peixes foram alimentados com ração comercial de 40% de proteína bruta durante o período experimental. Os dados foram submetidos à análise de variância e à regressão linear para estimativa do melhor ajuste a 5% de probabilidade. Os parâmetros produtivos como sobrevivência, peso inicial, peso final, conversão alimentar e taxa de crescimento específico não foram influenciados pela densidade de estocagem, assim como os parâmetros de qualidade da água. Entretanto, para a variável biomassa final, ganho de biomassa e consumo de ração total, o efeito foi significativo e estas apresentaram relação linear positiva com a densidade de estocagem. Avaliando os resultados, pode-se concluir que a densidade de estocagem de matrinxã (Brycon orthotaenia) até 120 peixes m-3 é a que proporciona maior produtividade e não representa efeitos negativos sobre o desempenho dos peixes.

The objective of this study was to determine the stocking density of matrinxã (Brycon orthotaenia) in cages, considering the productive performance. Juvenile Brycon orthotaenia (n = 5280) were distributed in 16 cages of 4m³ at densities of 45, 70, 95 and 120 fish m-3. The fish were fed with commercial feed with 40% crude protein during all experimental period. Data were subjected to analysis of variance and linear regression to estimate the best fit using 5% probability. The production parameters such as survival, initial weight, final weight, feed conversion and specific growth rate were not influenced by stocking density, as well as the parameters of water quality. However, final biomass, biomass gain and feed intake showed a positive linear relationship with stocking density. Evaluating these results, it was concluded that the stocking density of matrinxã (Brycon orthotaenia) up to 120 fish m-3 represent the best productive performance.

The objective of this study was to evaluate the morphometric growth and weight gain of strains of tilapia (Thai, Red, UFLA and Commercial) by nonlinear models. Initially, 500 male fingerlings of each strain, at 85 (Red and UFLA) and 86 (Thai and Commercial) days of age, were stocked separately in raceways with 56 m³. Twenty fish of each strain were randomly sampled, weighed and measured monthly. Five nonlinear models (Brody, von Bertalanffy, Gompertz, logistic and exponential) were tested, choosing one that best fit to the data. The variables studied were: weight, standard length (SL), head length (HL), height 1 (H1), height 2 (H2), height 3 (H3), first distance (D1), second distance (D2), first width (W1), second width (W2) and third width (W3). The exponential model had the best fit to weight and morphometric data, with the exception of W2, in which the best fitted model was von Bertalanffy. The convergence of the exponential model to data indicates that the cultivation period studied was not enough for the strains to reach maturity weight. The UFLA strain presented the lowest value for parameter "a" (initial weight estimate), 8.71 g, and the highest for parameter k (specific growth rate), 0.0127, when compared with other evaluated strains. However, the highest k of UFLA was not enough to overcome the final weight observed for the Commercial strain (603.1 g), which was higher than all other strains. Regarding the morphometric measurements, the UFLA strain also had the highest k for the variables SL, HL, HH, H1, H2, H3 and D2, and similar k to Commercial and Thai strains for the variables D1 and W3 respectively. The strains differ as to weight gain and morphometric growth.

The objective of this study was to verify which morphometric measures and ratios are more directly associated with the weight and body yields of rounded fish. A total of 225 specimens of rounded fish (59 pacus, 61 tambaquis, 52 tambacus and 53 paquis) with average weight of 972.43 g (±115.52 g) were sampled, stunned, slaughtered, weighed, measured, and processed for morphometric and processing yield analysis. The morphometric measures taken were: standard length (CP); head length (CC); head height (AC); body height (A1); and body width (L1). For completeness, the following morphometric ratios were calculated: CC/CP, AC/CP, A1/CP, L1/CP, CC/A1, AC/A1, L1/A1, CC/AC and L1/CC. The yields of carcass, filet, rib and filet with rib were estimated after processing. Initially, a "stepwise" procedure was performed in order to eliminate multicollinearity problems among the morphometric variables, and the phenotypic correlations were then calculated for the dependent variables (weight and body yields) and independent variables (morphometric measurements and ratios). These correlations were later deployed in direct and indirect effects through path analysis, and the direct and indirect contributions of each variable were measured in percentage terms. The CC and A1 measures were important for determining the weight of rounded fish. The CC/A1 ratio was the variable most directly associated with carcass yield. For filet, filet with rib and rib yields, the L1/CC ratio was found to be more appropriate and can be used directly.

The objective of this study was to evaluate the performance of three Nile tilapia Oreochromis niloticus strains cultivated in cages and subjected to different feeding programmes. Initially, 31,200 Nile tilapia juveniles with an average weight of 61.15 g were distributed in 48 cages. Two genetically improved strains were used together with one from the Fish Culture Section of Universidade Federal de Lavras (UFLA). The fish were subjected to four feeding programmes, consisting of different levels of crude protein (CP) in diets provided at different stages of cultivation. There was no interaction effect of the strain and feeding programme for most variables. The UFLA strain presented the highest weight gain, but with greatest lack of uniformity at the end of cultivation. The feeding programme with diets containing 36%, 32% and 28% CP, consecutively, promoted the highest weight gain and highest final biomass. The UFLA strain has great growth potential, justifying the development of a breeding programme for this strain. Crude protein levels below 36% for tilapias between 60 and 170 g and below 32% for tilapias between 170 and 700 g worsen fish performance.

Conduziram-se estes experimentos para avaliar os coeficientes de digestibilidade aparente dos nutrientes e da energia bruta da silagem ácida de resíduos da filetagem de tilápias e o desempenho produtivo da tilápia alimentada com dietas contendo (0, 10, 20, 30 e 40%) da silagem ácida em substituição à farinha de peixe. Na digestibilidade foram utilizados 200 alevinos revertidos sexualmente, com peso médio de 5,0 g e acondicionados em aquários de 40 litros. A coleta de fezes foi feita por metodologia indireta, utilizando-se 1,0% de Cr2O3 como indicador, incorporado à ração. No desempenho foram utilizados 2000 alevinos de tilápia nilótica, com peso médio inicial de 0,525g, acondicionados em hapas de 1m², dispostos em 1 viveiro escavado. As variáveis analisadas foram: ganho de peso final (GPF), consumo de ração total (CRT), conversão alimentar aparente (CAA) e acréscimo em comprimento (AC). O delineamento experimental foi o inteiramente casualizado, com cinco tratamentos e quatro repetições. Os valores de digestibilidade encontrados foram: coeficiente de digestibilidade aparente da matéria seca (CDA), 95,5%; CDA da proteína bruta, 96,7%; CDA do extrato etéreo, 97,2% e CDA da energia bruta, 95,4%. Não houve diferença significativa no consumo de ração total. Observou-se efeito quadrático para ganho de peso final, conversão alimentar aparente e acréscimo em comprimento. Conclui-se que este alimento pode ser eficientemente utilizado pela tilápia nilótica.

The experiments were carried out in order to evaluate the apparent digestibility coefficients of the nutrients and gross energy of acid silage of filetage residues of the Nile tilapia. The treatments were based on the increasing levels (0, 10, 20, 30, 40%) of the acid silage by substitution of fish meal in the diets. In the digestibility assay a total of 200 sexually inverted juveniles were used. The average weight was 2.0 g and were kept in 40 liter aquariums. Feces collect was made during seven subsequent days and the apparent digestibility coefficients and apparent digestible energy were determined by indirect method, using 1.0% of Cr(2)0(3) as an indicator. In the performance assay 2000 sexually inverted juveniles were used, with average weight of 0.45g, kept in 1m² hapas, in a fish crawl. The analyzed variables were: final weight (FWG), total feed intake (TFI), apparent feed conversion (AFC) and length increase (LI). The randomized outline was used with five treatments and four repetitions. The values for apparent digestibility were: apparent digestibility coefficient of dry matter, 95.49%; apparent digestibility coefficient of gross protein, 96.66%; apparent digestibility coefficient of ether extract, 97.18%; apparent digestibility coeficient of gross energy, 95.44%. There was no significant difference (P>0.05) for total feed intake (TFI). One observed a quadratic effect (P<0.01) in the final weight (FWG), apparent feed conversion (AFC) and length increase. One concluded that the acid silage of filetage residues should be efficiently used by the Nile tilapia.

Com o objetivo de avaliar curvas de crescimento morfométrico de linhagens de tilápias em função dos pesos de abate, um experimento foi conduzido no setor de piscicultura da Universidade Federal de Lavras, M.G.- Brasil. Foram avaliados 362 peixes da linhagem Chitralada e 345 da Supreme, pesando entre 1,7 e 800 g. Com o crescimento dos animais, amostras aleatórias foram tomadas, sendo os peixes abatidos, pesados e submetidos à avaliação morfométrica. Foram ajustados diferentes modelos de crescimento de medidas corporais em função do peso de abate. Pequenas diferenças entre os ajustes dos modelos foram encontradas para o valor assintótico (A) e grandes diferenças para a taxa de crescimento relativo à maturidade (K) para todas as medidas. Os modelos de Brody e Logístico apresentaram maiores diferenças, ficando os modelos de Gompertz e von Bertalanffy em posição intermediária. A linhagem Supreme obteve valores de "A" ligeiramente maiores, para o comprimento padrão (CP), e ligeiramente menores, para a altura do corpo, em relação aos valores obtidos pela linhagem Chitralada, e essa apresentou maior "K" para a relação comprimento da cabeça/comprimento padrão. Conclui-se que os modelos não lineares de Gompertz, Brody, von Bertalanffy e Logístico descrevem adequadamente o crescimento morfométrico de tilápias do Nilo em função do peso corporal, sendo mais indicados os modelos de Gompertz e von Bertalanffy, tanto para a linhagem Chitralada quanto para a Supreme, considerando que foram pequenas as diferenças existentes entre as duas linhagens.

The objective of this research was to evaluate the morphometric growth curves of tilapia strains in function of the body weight, an experiment was carried out at the Fish Culture of the Animal Sciences Department, Federal University of Lavras, M.G-Brazil. Three hundred sixty-two (362) fish of the Chitralada strain and three hundred forty-five (345) of the Supreme strain, weighting between 1,7 and 800 g were used. With the animals' growth, random samples were taken; the fish were slaughtered, weighted and submitted morphometric evaluation. Different models of growth of body measurements in function of the body weight were fitted. In general, the measurements were adequately adjusted. Shorts differences were found between the fit of the models for limiting values (A) and high differences for growth rate relative the maturity (K) for all the measurements. The Brody and Logistic models had higher differences than Gompertz and von Bertalanffy that stayed in intermediary position. The Supreme strain had "A" for standard length (SL) slightly higher and for body height slightly smaller than Chitralada strain. The Chitralada strain had higher "K" for head length/standard lenght relation than Supreme strain. The Gompertz, Brody, von Bertallanffy e Logistic models described adequately the morphometric growth of tilapia in function of body weight, being more indicate the models Gompertz and von Bertalanffy. The differences between Chitralada and Supreme tilapia strains were small.

Com o objetivo de avaliar os rendimentos do processamento de linhagens de tilápias em função dos pesos de abate, um experimento foi conduzido no setor de piscicultura da Universidade Federal de Lavras, M.G. - Brasil. Foram utilizados 93 peixes da linhagem Chitralada e 78 da Supreme, pesando entre 150 e 790 g. Os peixes foram cultivados em dois tanques de alvenaria de 40 m², sendo alimentados com ração comercial fornecida de acordo com a biomassa e a temperatura da água. A temperatura e o oxigênio da água foram tomados diariamente, no início do dia e no final da tarde, e o pH aferido semanalmente. Com o crescimento dos animais, amostras aleatórias foram tomadas. Nas amostragens, os peixes foram abatidos após terem passado por um jejum de 24 horas e insensibilização por choque térmico. Em seguida, foram pesados e dissecados. A análise de regressão indicou que em pesos mais elevados, a linhagem Chitralada apresenta maior porcentagem de cabeça e rendimento de pele. A linhagem Supreme apresentou maior peso de carcaça, filé e resíduos, sendo mais expressivos em pesos superiores a 500 g e menor valor à maturidade para a % de vísceras. Conclui-se que as duas linhagens possuem crescimento das partes componentes proporcional ao aumento do peso corporal, e este aumento não altera o rendimento desses constituintes. A linhagem Supreme apresentou maiores rendimentos de carcaça e filé do que a Chitralada, sendo a mais indicada para a produção e comercialização de filés mais pesados.

With the objective of evaluating the yield processing of tilapia strains in function of body weight, an experiment was carried out at the Fish Culture of the Animal Sciences Department, Federal University of Lavras, M.G. - Brazil. A total 93 fish of the Chitralada strain and 78 of the Supreme strain, weighting between 150 and 790 g were used. The fish were cultivated in two tanks of 40 m², fed with commercial ration supplied according to the biomass and water temperature. The water temperature and oxygen were evaluated every day, at the early morning and at the late afternoon, and the pH checked weekly. During the fish growth, random samples were taken. After 24 hours of fasting, the fish were insensibilized (thermal shock), slaughtered (anoxia), weighted and dissected. The regression analysis showed that in higher weight, the Chitralada strain presented higher head percentage and skin yield. The Supreme strain presented higher carcass, fillet and residue weights, being more expressive in body weights superior to 500 g and smaller limiting value for the percentage of viscera. It was concluded that the two strains have growth of body parts proportional to the increase of the body weight, and this increase does not modify the parts yield. The Supreme strain showed more carcass and fillet yield than Chitralada, and is should be indicated for production and commercialization of heavier fillet.

Objetivou-se, com o presente trabalho, avaliar o efeito do peso de abate sobre os rendimentos do processamento do peixe teleósteo piracanjuba (Brycon orbignyanus, Valenciennes, 1849). Inicialmente, alevinos com peso médio de 12 g, oriundos da Estação Experimental da Usina Hidrelétrica de Itutinga, foram estocados e cultivados em um viveiro de terra na Estação de Piscicultura do Departamento de Zootecnia da Universidade Federal de Lavras. Ao final de 18 meses de cultivo, 121 peixes foram insensibilizados, abatidos, pesados e dissecados, para a determinação das porcentagens de cabeça (%CAB), nadadeiras (%NAD), vísceras (%VIS), pele com escamas (%PE), e resíduos da filetação (%RF) e dos rendimentos de carcaça (RCAR) e de filé sem pele (RFSP), em relação ao peso de abate. Para as análises de variância, os dados obtidos foram agrupados em 4 classes de peso (CP1=515 g a 629 g; CP2=630 g a 744 g; CP3=745 g a 859 g; e CP4=860 g a 975 g) e as equações de regressão estimadas em função do peso médio de cada classe. Não foi constatado (P>0,05) efeito de classe de peso sobre RCAR, %NAD e %PE. Por outro lado, observaram-se efeito linear do peso de abate sobre %CAB (P<0,01), %RF (P<0,01) e RFSP (P<0,09), e efeito quadrático sobre %VIS (P<0,05). As variáveis %CAB e %RF diminuíram, ao passo que o RFSP e %VIS aumentaram, com o aumento do peso de abate. Pode-se concluir que, nas condições em que o experimento foi realizado, piracanjubas com maiores pesos de abate proporcionam maior RFSP e menores %CAB e %RF. Entretanto, a redução da %CAB não foi suficiente para aumentar o RCAR como seria esperado, em razão provavelmente de um maior aumento da %VIS.

The objective of this study was to evaluate the effect of body weight on processing yields of a teleost fish piracanjuba (Brycon orbignyanus, Valenciennes, 1849). Firstly, fingerlings were reared in ponds in the Fish Culture of the Animal Sciences Department, Federal University of Lavras, M.G. - Brazil, for 18 months. Then, 121 fishes were insensibilized, slaughtered, weighed and dissected, in order to determine the percentages of head (%CAB), fins (%NAD), visceras (%VIS), skin with scales (%PE), and fillet residues (%RF), and the carcass yield (RCAR) and fillet without skin yield (RFSP), in relation to body weight. For analyses of variances, data were distributed over four weight classes (CP1 = 515 to 629g; CP2 = 630 to 744g; CP3 = 745 to 859g; and CP4 = 860 to 975g) and the regression equations were estimated in function of mean weight of each class. There was no effect (P>0,05) of weight class on RCAR, %NAD and %PE. However, a linear effect of body weight on %CAB (P<0,01), %RF (P<0,01) and RFSP (P<0,09) and a quadratic effect on %VIS (P<0,05) were observed. The %CAB and %RF decreased while RFSP and %VIS increased, with the increase of body weight. Based on these results, it can be concluded that heavier piracanjubas provide larger RFSP, smaller %CAB and smaller %RF. The smaller %CAB on heavier fish did not increase RCAR, as expected probably because of the increase on %VIS.