Resumo: O objetivo deste trabalho foi avaliar a suplementação da dieta de pacu e tambacu com silagem ácida de pescado durante o inverno. O delineamento experimental foi feito em arranjo fatorial 2 × 2 (dois grupos genéticos e duas dietas), com três repetições. O fator grupos genéticos foi composto pelo pacu (Piaractus mesopotamicus) e pelo tambacu (♀ Colossoma macropomum × ♂ Piaractus mesopotamicus). As duas dietas foram compostas com base em ingredientes vegetais; uma delas foi suplementada com silagem ácida de pescado (dieta silagem), e a outra foi uma dieta base sem suplementação. Doze tanques-rede, seis deles com pacu e seis com tambacu, foram utilizados como unidades experimentais, com dez peixes em cada um. Houve interação entre os fatores quanto ao comprimento final, massa final e ganho diário de massa. O pacu alimentado com a dieta silagem apresentou maior crescimento do que o pacu alimentado com a dieta base; no entanto, este efeito não foi observado no tambacu. Observou-se eficiência alimentar maior no pacu do que no tambacu, sem efeito das dietas. A suplementação da dieta com silagem ácida de pescado melhora o desempenho produtivo do pacu criado em temperatura subótima fria, mas não tem este efeito sobre o tambacu.

Abstract: The objective of this work was to evaluate the supplementation of diet of pacu and tambacu with acid fish silage during winter. The experimental design was a 2 × 2 factorial arrangement (two genetic groups and two diets), with three replicates. The genetic group factor was composed of pacu (Piaractus mesopotamicus) and tambacu (♀ Colossoma macropomum × ♂ Piaractus mesopotamicus). The two diets were based on plant ingredients; one of them was supplemented with acid fish silage (silage diet), and the other was a base diet without supplementation. Twelve net tanks, six from which with pacu, and six with tambacu, were used as experimental units, with ten fish in each tank. There was an interaction of the factors for final length, final weight, and daily weight gain. Pacu fed the silage diet showed a higher growth than pacu fed with the base diet; however, this effect was not observed for tambacu. A higher feed efficiency was observed for pacu than for tambacu, without a diet effect. The diet supplementation with acid fish silage improves the productive performance of pacu reared at cold suboptimal temperature, but it does not have this effect on tambacu.

O conhecimento de como os animais depositam componentes químicos como água, proteína, gordura e cinzas na carcaça é importante para a formulação de uma dieta equilibrada, permitindo o máximo desempenho com baixo impacto ambiental. Logo, o trabalho foi conduzido, com o objetivo de avaliar a influência de diferentes linhagens de tilápia sobre a deposição de componentes químicos na carcaça. Os componentes corporais analisados foram água, proteína, gordura e cinzas. Para a determinação das curvas de deposição química corporal em função da idade foram ajustados os modelos exponencial, Brody, logístico, Gompertz e vonBertalanffy. Houve ajuste apenas do modelo exponencial para a água, tendo as linhagens UFLA e Comerciais as que depositaram numa velocidade mais rápida (P<0,05) em relação às demais linhagens. Quanto à proteína, a linhagem Vermelha foi a que teve menor peso à maturidade, estimado (49,37g) e foi mais precoce quanto à deposição máxima em relação as outras linhagens (Chitralada, UFLA e Comercial), no qual obtiveram peso a maturidade estimada em 231,5g e deposição máxima aos 337 dias de idade. Não houve diferença (P>0,05) dos parâmetros do modelo logístico entre as linhagens Vermelha,UFLA e Comercial para extrato etéreo, sendo a deposição máxima (0,23 g) aos 310 dias de idade. Em relação à deposição de cinzas, a linhagem Comercial teve maior deposição máxima (0,10 g) e, aos 337 dias de idade, sendo mais tardia em relação as outras linhagens que obtiveram deposição máxima de 0,033 g, aos 254 dias de idade. Portanto, conclui-se que as linhagens genéticas avaliadas diferem quanto às curvas de deposição química de água, proteína, extrato etéreo e cinzas.

The knowledge of how animals deposited chemical components as water, protein, fat and ash in the carcass is importance for the formulation of a balanced diet, allowing maximum performance with a low environmental impact. So, the study was carried out to evaluate the influence of different tilapia strains (Chitralada, Commercial, Red and Universidade Federal de Lavras [UFLA]) on the deposition of bodily chemical components in the carcass. The bodily components analyzed were water, protein, fat and ash. For the determination of the bodily chemical deposition curves by age, the exponential, Brody, logistic, Gompertz and von Bertalanffy models were adjusted. The Commercial and UFLA strains deposited water at a faster speed (P<0.05) compared with the remaining strains. As for protein, the Red strain had a lower estimated maturity weight (49.37 g), and was more precocious (202 days) with regard to maximum deposition in comparison to the other strains (Chitralada, UFLA and Commercial) in which there was an estimated maturity weight of 231.5 g and maximum depositionfor 337 days. There were no differences (P>0.05) for the logistic model parameter between Red, UFLA and Commercial strains for fat, which presented a maximum fat deposition (0.23 g) at 310 days of age. Regarding ash deposition, the Commercial strain presented a higher maximum deposition (0.10 g) at 337 days, occurring later than the other strains that presented maximum deposition (0.033g) at 254 days of age. Thus, it was concluded that the genetic strains evaluated differ in chemical deposition curves of water, protein, fat and ash.

Para o desenvolvimento de uma tecnologia de cultivo é necessária a determinação da densidade de estocagem ideal. Objetivou-se determinar a melhor densidade de estocagem para juvenis de Brycon orthotaenia, cultivados em tanques-rede, durante a fase de recria. A pesquisa foi conduzida na Fazenda Experimental da Epamig, em Felixlândia, Estado de Minas Gerais, na represa de Três Marias. Foram utilizados 9.000 alevinos, distribuídos em 12 berçários com 2 m³ em tanques-rede, seguindo o delineamento inteiramente casualizado, com três repetições e quatro diferentes densidades de estocagem (150, 300, 450, 600 peixes m-3). Amostras aleatórias de cada tanque-rede foram coletadas para as avaliações, no início do experimento e aos 60 dias de cultivo. Foram estimados os parâmetros produtivos, índice de crescimento específico e uniformidade. Obteve-se uma relação linear positiva (p < 0,05) para biomassa final (r² = 0,88), ganho de peso da biomassa (r² = 0,87), produtividade (r² = 0,86), conversão alimentar aparente (r² = 0,96) e para viabilidade econômica (r² = 0,96). Para sobrevivência (r² = 0,98), a relação linear foi negativa (p < 0,05). Não houve diferença significativa entre os tratamentos (p > 0,05) para os parâmetros de crescimento, uniformidade e peso final. Conclui-se que a densidade de 300 peixes m-3 é a mais indicada, pois, proporciona maior receita líquida, sobrevivência e boa conversão alimentar.

Developing a rearing technology requires the determination of the optimum stocking density. This study aimed to determine the best stocking density for Brycon orthotaenia juveniles grown in net cages, during the rearing phase. The research was conducted at the Experimental Farm of EPAMIG, in Felixlândia, Minas Gerais State, in the Três Marias Reservoir. 9,000 fingerlings were distributed into 12 net cages, 2 m³ each, according to a completely randomized design with three replications and four different stocking densities (150, 300, 450, 600 fish m-3). Random samples were taken from each net cage, at the onset of the experiment and at 60 rearing days, to assess production parameters, specific growth rate and uniformity. We verified a positive linear relationship (p < 0.05) for final biomass (r² = 0.88), weight gain (r² = 0.87), productivity (r² = 0.86), apparent feed conversion (r² = 0.96) and economic viability (r² = 0.96). For survival (r² = 0.98), the relationship was negative (p < 0.05). There were no significant differences between treatments (p > 0.05) for growth parameters, uniformity and final weight. It can be concluded that the density of 300 fish m-3 is the most suitable, because it provides higher net revenue, survival, and a good feed conversion.

The main factor considered in breeding programs for fish is growth, which can be assessed in terms of a gain in either weight or body measurements. This study was undertaken to evaluate the morphometric traits of GIFT strain tilapia (Oreochromis sp.) selected for weight gain. The data set used contained information on 6,650 animals. The genetic values of 8,590 animals in a relationship matrix of five generations were predicted. The following morphometric measurements were evaluated: standard length; body depth and body width. Body area and volume were also calculated. Bi-character analyses involving morphometric traits were used to estimate (co)variance components. Heritability, larval and fingerling common environmental effects were estimated for each trait, together with the genetic and phenotypic correlations between traits. Bayesian procedures were utilised by Gibbs chains, and the convergence of the chains was tested using the Heidelberger and Welch method. Genetic trends were estimated by segmented regression of the fish breeding values of the generations considered in this study. Estimates of heritability (0.28 a 0.31) had moderate to high magnitudes for all traits. Genetic correlations between traits were all above 0.8, and the genetic gains were satisfactory from the third generation onwards. From the estimates of the genetic parameters and genetic gain the morphometric traits evaluated have good potential for selection.

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.

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.

With the purpose of evaluating the changes and the degree of heterosis on performance and carcass traits of fish from the diallel crossing between Pacu and Tambaqui, four genetic groups were generated through hormonal induction: pacu, tambaqui, tambacu and paqui. For 196 days, 400 juveniles of each genetic group were stocked in a pond divided into four parts of equal size, one for each group. At the end of this period, when the fish weighed on average 1024 g (±115.52 g), 20 specimens of each genetic group were sampled, weighed, measured: head length; standard length; body height; and width; and also processed resulting in following body yield: viscera; carcass; head; fillet; rib; residue and skin yields. There was positive heterosis for body weight, viscera and skin yield and head measures and negative heterosis for carcass and filet yield and body width, indicating that the hybrids have better performance on weight gain, but are inferior in relation to the carcass conformation.

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.

Este trabalho foi realizado para se obter uma equação de predição para estimar os valores de energia metabolizável aparente corrigida (EMAn) dos alimentos proteicos usualmente utilizados em rações para frangos de corte utilizando-se o princípio da meta-análise. Realizou-se uma revisão bibliográfica de estudos no Brasil para catalogar informações sobre valores de EMAn e composição química dos alimentos: proteína bruta (PB), extrato etéreo (EE), matéria mineral (MM), fibra bruta (FB), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA). Foram considerados os efeitos de: sexo, em três níveis (macho, fêmea e mistos); idade, em quatro níveis (1ª e 2ª semana de vida, 3ª e 4ª semana, 5ª e 6ª semana e acima ou indefinido) e metodologia empregada no metabolismo em dois níveis: coleta total (CT) e alimentação forçada + (CT). Os dados foram analisados em um esquema fatorial 3 × 4 × 2, podendo totalizar até 24 grupos, adotando-se o procedimento Stepwise para a seleção de variáveis e o Proc Reg do (SAS) para ajustar o modelo de regressão linear múltipla. A equação obtida que melhor se ajustou foi EMAn = 2707,71 + 58,63EE - 16,06FDN (R² = 0,81), sendo o EE a variável mais importante, em se tratando de possíveis variações nos teores energéticos dos alimentos proteicos.

This study was accomplished aiming to obtain prediction equations to estimate the values of corrected apparent metabolizable energy (AMEn) of the protein feedstuffs usually used in broiler rations, through the meta-analysis principle. Literature review of the studies realized in Brazil was performed to catalog information about values of AMEn and chemical composition of the feedstuffs reported (CP = crude protein; EE = ether extract; CF = crude fiber; NDF = neutral detergent fiber; ADF = acid detergent fiber). Effects of sex at three levels (male; female and mixed); age at four levels (1st and 2nd weeks of life; 3rd and 4th weeks; 5th and 6th weeks; above or indefinite) and the methodology employed in the metabolism assay at two levels (total collection of excreta - CT and forced fed plus + CT) were considered. The data were analyzed in a 3 × 4 × 2 factorial arrangement, capable of amounting up to 24 groups. The Stepwise procedure was adopted for selection of variables, and the Proc Reg of the (SAS), to fit the multiple linear regression model. The equation obtained which best fitted was AMEn = 2707.71 + 58.63EE - 16.06NDF (R² = 0.81), with the EE as the most important variable, concerning the possible variations in the energy contents of protein feedstuffs.