Ractopamine as a metabolic modifier feed additive for finishing pigs: a review

The β-adrenergic agonist ractopamine is increasingly used in the swine industry due to higher consumer demand for leaner pork products. Redirecting nutrients to favor leanness rather than fat deposition, ractopamine improves growth and carcass traits of finishing pigs. However, the impact of this agonist on pork quality is not clearly defined. Understanding the biological effects of dietary ractopamine dose, treatment period, lysine levels, and the lysine to metabolizable energy ratio will help pork producers achieve improvements in animal performance, carcass leanness, and economic efficiency in swine production systems.

Improvement of photon transport model by including coupled photon-electron transport and kernel refinement

The first part of this work deals with the inverse problem solution in the X-ray spectroscopy field. An original strategy to solve the inverse problem by using the maximum entropy principle is illustrated. It is built the code UMESTRAT, to apply the described strategy in a semiautomatic way. The application of UMESTRAT is shown with a computational example. The second part of this work deals with the improvement of the X-ray Boltzmann model, by studying two radiative interactions neglected in the current photon models. Firstly it is studied the characteristic line emission due to Compton ionization. It is developed a strategy that allows the evaluation of this contribution for the shells K, L and M of all elements with Z from 11 to 92. It is evaluated the single shell Compton/photoelectric ratio as a function of the primary photon energy. It is derived the energy values at which the Compton interaction becomes the prevailing process to produce ionization for the considered shells. Finally it is introduced a new kernel for the XRF from Compton ionization. In a second place it is characterized the bremsstrahlung radiative contribution due the secondary electrons. The bremsstrahlung radiation is characterized in terms of space, angle and energy, for all elements whit Z=1-92 in the energy range 1–150 keV by using the Monte Carlo code PENELOPE. It is demonstrated that bremsstrahlung radiative contribution can be well approximated with an isotropic point photon source. It is created a data library comprising the energetic distributions of bremsstrahlung. It is developed a new bremsstrahlung kernel which allows the introduction of this contribution in the modified Boltzmann equation. An example of application to the simulation of a synchrotron experiment is shown.

Substituting Wet Distillers Grains or Condensed Distillers Solubles for Corn Grain in Finishing Diets for Yearling Heifers

A feeding trial was conducted with 790-lb yearling heifers fed an average of 121 days to evaluate replacing cracked corn and supplemental urea with wet distillers grains or condensed distillers solubles. Wet distillers grains were evaluated at 16%, 28% and 40% of diet dry matter. Condensed distillers solubles were added at 6.5% of diet dry matter. Control diets were supplemented with urea or a combination of urea and soybean meal. Feeding 16% wet distillers grains or condensed distillers solubles increased gain of heifers compared with those fed the control urea diet. Increasing the amount of wet distillers grains tended to decrease feed intake and reduce gain. The calculated apparent net energy based on gain of the heifers was greatest for the heifers fed 16% wet distillers grains. The apparent energy of the wet distillers grains declined as the quantity fed was increased. The calculated net energy values were 1.09 and 1.35 Mcal/lb of dry matter for the average of the three concentrations of wet distillers grains and condensed distillers solubles. These results confirm the high energy values of wet distillers grains relative to cracked corn as observed in a previous steer feeding trial.

Dietary xylanase increases hepatic vitamin E concentration of chickens fed wheat based diet

The study examined the effect of xylanase supplementation on apparent metabolizable energy (AME) and hepatic vitamin E and carotenoids in broiler chickens fed wheat based diets. A total of one hundred forty four male Ross 308 chickens were used in this study. Birds were randomly assigned to 3 dietary treatments (8 cages per treatment of 6 male broilers each) for 14 days from 7 to 21 day old. The control treatment was based on wheat-soyabean meal and was either unsupplemented or supplemented with either 1000 or 2000 xylanase units per kg diet. Orthogonal polynomial contrasts were used to test linear response to dietary xylanase activity. There was a positive linear relationship (P < 0.05) between dietary AME and doses of supplementary xylanase. A linear relationship (P < 0.05) was also observed between dosage of xylanase supplementation and hepatic vitamin E concentration and retention. In conclusion, xylanase supplementation improved dietary AME and increased hepatic vitamin E concentration which may have positive effects on the antioxidative status of the birds.

Investigación sobre fermentaciones metánicas de desechos estacionales

En el campo agrícola se producen una serie de desechos orgánicos, que por un lado representan serios problemas de contaminación ambiental y por otro el desperdicio de valores energéticos importantes. Es decir una acción contraria a la sostenibilidad que debe buscarse en este siglo XXI. Entre estos productos agrícolas pueden citarse la pulpa de café, residuos herbáceos, bagazo de caña y la fracción insoluble de estiércol de ganado porcino conocida como cerdaza. Un problema añadido para dar solución adecuada es la disponibilidad de estos solo en cortas épocas del año. Todo lo anterior ha sido el origen de la presente investigación, para dar solución adecuada tanto en el aprovechamiento de biogás como en la reducción de la contaminación. La investigación descrita en este documento contempla el desarrollo de los siguientes aspectos: 1) Caracterización y problemática de cada uno de los productos señalados, 2) la solución al problema mediante el proceso de digestión anaerobia con fases separadas con el aprovechamiento del biogás generados y 3) recomendaciones para el arranque del proceso de digestión anaerobia y su mantenimiento en una alternancia de los productos citados. En la primera etapa de la fase experimental se estimó el rendimiento específico de metano para los diferentes sustratos, utilizando reactores batch configurados en una y dos fases concluyendo que la digestión anaerobia en dos fases presenta diferentes ventajas sobre la digestión monoetapa. En general se obtuvo un mayor rendimiento en la producción de metano, una reducción en los tiempos de retención, mayor eficiencia en la eliminación de los sólidos volátiles agregados, y una mayor estabilidad en el proceso reflejado en el mantenimiento de valores de pH en los rangos de operación recomendados. Seguidamente, al comparar dos procesos para la puesta en marcha de digestores metanogénicos operados en forma continua, se concluye que las variables determinantes en la estabilidad del sistema son la alcalinidad total presente en el digestor, el establecimiento de la población de microorganismos y la carga orgánica aplicada. Las dos primeras están determinadas por la calidad y proporción del inóculo suministrado al inicio del proceso. La alternación de sustratos suministrados al sistema de digestión en dos fases, permitió determinar el impacto sobre el desempeño del mismo, registrando una reducción en la producción de biogás, la riqueza de metano y la eficiencia de eliminación de sólidos volátiles durante los primeros días de operación luego del cambio de sustrato. Este periodo corresponde al proceso de aclimatación de los microorganismos el cual requirió de 20 días para asimilar los componentes del nuevo sustrato. Finalmente, entre los sustratos analizados, la menor carga orgánica de operación para mantener la operación del sistema en continuo corresponde a la pulpa de café con 0.1 kg SV/m3. La composición de este sustrato favorece la rápida acumulación de acidez volátil en el sistema, proporcionando una tendencia a la acidificación. Sin embargo, al controlar las cargas orgánicas volumétricas, el sistema permaneció operando sin necesidad de adición de alcalinizantes. La aplicación de los resultados de la presente investigación a la problemática de residuos de café es alentadora, comprobando que el sistema puede ser operado en continuo alternando residuos boreales y pulpa de café, ambos sustratos disponibles en las plantas de procesamiento de la cereza de café. ABSTRACT In the agricultural field there are series of organic wastes, which in one hand are the source of serious problems of environmental pollution and in the other, they represent a residue that could be used as a feedstock with significant energy values. These actions are contrary to efforts towards sustainability, which should be a priority in this century. Among agricultural residues with significant abundance, the coffee pulp, herbaceous waste, sugarcane bagasse and the insoluble fraction of pig manure can be mentioned. An added problem to the development of appropriate treatment systems, which provides a solution to the disposal of such wastes, is the limited availability of these feedstocks only in short seasons. These arguments have been the source of our research, in order to provide properly measures to biogas usage and pollution reduction. The research presented in this document includes the approaches to the following aspects. 1) Characterization and problems regarding the selected feedstocks 2) the solution to the problem by anaerobic digestion process with separate phases and 3) recommendations for starting the process of anaerobic digestion and its maintenance with alternation of the products listed For the first stage of the experimental phase, the specific methane yield of the selected feedstocks was estimated using batch reactors configured in one and two phases. It was concluded that two-phase anaerobic digestion offered distinct advantages over the single-stage digestion. In general a higher methane production yields, lower retention times, higher efficiency in volatile solids removal, and increased stability among the process were obtained. When comparing two processes for starting up methanogenic digesters, it is concluded that the variables that determine the stability of the system are the total alkalinity in the digester, the establishment of the population of microorganisms and the organic load. The first variables are influenced by the proportion and quality of the inoculum supplied at the beginning of the process. The alternation of substrates gave as a result a negative impact on system performance, recording a reduction on biogas production, the methane concentration and the efficiency of volatile solids removal. The situation was observed during the first days of operation after the change of feeding. This period corresponds to the process of acclimatization of the microorganisms which required 20 days to assimilate new substrate components. Finally, among substrates studied, the lowest organic load applied to maintain a continuous operation of the system, corresponds to the coffee pulp with 0.1 kg VS / m3. The composition of this substrate promotes a rapid accumulation of volatile acidity within the system, providing a tendency to acidification. However, by controlling organic loads, the operating system remained stable without addition of alkalizing components. The application of the results of this research to the problem of coffee waste is promising, proving that an anaerobic system can be operated continuously by alternating boreal waste and coffee pulp, both substrates available in coffee processing plants.

A quantitative method for evaluating the stabilities of nucleic acids

We report a general method for screening, in solution, the impact of deviations from canonical Watson-Crick composition on the thermodynamic stability of nucleic acid duplexes. We demonstrate how fluorescence resonance energy transfer (FRET) can be used to detect directly free energy differences between an initially formed “reference” duplex (usually a Watson-Crick duplex) and a related “test” duplex containing a lesion/alteration of interest (e.g., a mismatch, a modified, a deleted, or a bulged base, etc.). In one application, one titrates into a solution containing a fluorescently labeled, FRET-active, reference duplex, an unlabeled, single-stranded nucleic acid (test strand), which may or may not compete successfully to form a new duplex. When a new duplex forms by strand displacement, it will not exhibit FRET. The resultant titration curve (normalized fluorescence intensity vs. logarithm of test strand concentration) yields a value for the difference in stability (free energy) between the newly formed, test strand-containing duplex and the initial reference duplex. The use of competitive equilibria in this assay allows the measurement of equilibrium association constants that far exceed the magnitudes accessible by conventional titrimetric techniques. Additionally, because of the sensitivity of fluorescence, the method requires several orders of magnitude less material than most other solution methods. We discuss the advantages of this method for detecting and characterizing any modification that alters duplex stability, including, but not limited to, mutagenic lesions. We underscore the wide range of accessible free energy values that can be defined by this method, the applicability of the method in probing for a myriad of nucleic acid variations, such as single nucleotide polymorphisms, and the potential of the method for high throughput screening.

Propriedades magnéticas de trímeros de FexCo1-x depositados em Pt(111)

Quais propriedades magnéticas são modificadas quando se agrupam átomos de Fe/Co para formar estruturas quasi-2D, se comparadas aos nanofios (quasi-1D) de FexCo1-x? E como estas propriedades reagem com a variação da proporção de Fe/Co nos aglomerados? A fim de responder a estas questões, trímeros de FexCo1-x depositados em Pt(111) são investigados utilizando o método de primeiros princípios Real Space-Linear Muffin-Tin Orbital-Atomic Sphere Approximation (RS-LMTO-ASA) no âmbito da Teoria do Funcional da Densidade (DFT). Diferentes configurações de trímeros triangulares são consideradas, variando-se as posições e a concentração dos átomos de Fe/Co. Neste trabalho, demonstra-se a ocorrência de uma tendência não-linear estritamente decrescente dos momentos orbitais médios como função da concentração de Fe, distinta do encontrado tanto para os nanofios de FexCo1-x (dependência linear) quanto para a monocamada correspondente (dependência não-linear). Os resultados obtidos mostram ainda que os momentos orbitais variam com o ambiente local e com a direção de magnetização, especialmente quando associados aos átomos de Co, em concordância com publicações anteriores. A mudança de dimensionalidade quasi-1D (nanofios) para quasi-2D (trímeros compactos) não afeta o comportamento dos momentos de spin, que permanecem descritos por uma função linear com respeito à proporção de Fe/Co. Ambos o formato e a concentração de Fe nos sistemas apresentam um papel importante nos valores de energia de anisotropia magnética. Em adição, observou-se que o subtrato de Pt opera ativamente na definição das propriedades magnéticas dos aglomerados. Embora todas as configurações lineares e compactas dos aglomerados de FexCo1-x sejam estáveis e exibam interações fortemente ferromagnéticas entre os primeiros vizinhos, nem todas revelaram o ordenamento colinear como estado fundamental, apresentando uma interação de Dzyaloshinskii-Moriya não-desprezível induzida pelo acoplamento spin-órbita. Estes casos específicos são: o trímero triangular de Co puro e o trímero linear (nanofio) de Fe puro, para o qual foi verificado o acoplamento do tipo Ruderman-Kittel-Kasuya-Yosida entre os átomos de Fe constituintes. Os resultados obtidos contribuem para o entendimento de quais mecanismos definem o magnetismo nos trímeros de FexCo1-x/Pt(111), e discutem as questões presentes atualmente na literatura no contexto destes sistemas.

Aditivos (ionóforo e não ionóforo), processamento de grãos de milho e concentrações de fibra insolúvel em detergente neutro (FDN) de silagem de milho em dietas para bovinos em terminação

Foram conduzidos dois experimentos com o intuito de se avaliar o desempenho, características de carcaça e parâmetros ruminais de bovinos Nelore recebendo dietas contendo grãos de milho flint processados de diferentes formas em associação a diferentes aditivos e níveis de FDN de silagem de milho (FDNf). No Experimento 1, 239 tourinhos (PCI=350±26,79kg) foram alojados em 40 baias de acordo com o peso corporal inicial e receberam dietas contendo dois tipos de processamento dos grãos de milho (moagem fina e floculação) e diferentes aditivos (monensina sódica; 25 ppm e formulação A062 a base de virginiamicina; produto teste, não comercial, fornecido pela Ourofino Saúde Animal; nas dosagens de 17 e 25 ppm), totalizando 8 tratamentos. Os dados foram analisados pelo PROC MIXED do SAS. A floculação aumentou o peso final, o ganho de peso diário, a eficiência alimentar, o peso da carcaça quente e tendeu a aumentar o rendimento de carcaça em comparação a moagem fina. Houve tendência de interação entre processamento e fornecimento de aditivos para a ingestão de matéria seca e ganho de peso diário. A floculação reduziu o teor de amido fecal, aumentou a digestibilidade do amido no trato total, aumentou os valores de energia liquida para manutenção e ganho da dieta e o numero médio de papilas ruminais. Os aditivos aumentaram a altura, largura e área das papilas e reduziram a espessura de faixa de queratina em relação ao tratamento controle. Houve tendência das formulações a base de virginiamicina aumentarem o peso da carcaça quente dos animais em comparação com a monensina sódica, mas não em relação ao tratamento controle sem aditivo. A floculação foi mais efetiva para aumentar a digestiblidade do amido no trato total, o valor energético do milho e o desempenho dos bovinos enquanto que os aditivos não foram efetivos para aumentar o valor energético das dietas e a eficiência alimentar dos animais. No Experimento 2, 237 tourinhos (PCI=350±28,49kg) foram alojados em 32 baias de acordo com o peso corporal inicial e receberam dietas contendo dois tipos de processamento (moagem grosseira e floculação) e diferentes níveis de FDNf (4; 7; 10 e 13% MS), totalizando 8 tratamentos. Os dados foram analisados pelo PROC MIXED do SAS. A floculação tendeu a aumentar a eficiência alimentar, o peso da carcaça quente e a espessura de gordura subcutânea, reduziu o teor de amido fecal, aumentou a digestibilidade do amido no trato total como também aumentou os valores de energia liquida para manutenção e para ganho das dietas. Os níveis de FDNf afetaram ingestão de matéria seca e o peso da carcaça quente independente do método de processamento. Houve tendência de aumento linear no GPD e tendência de redução quadrática na eficiência alimentar com inclusão crescente de FDNf. A inclusão de silagem de milho em dietas com alto teor de milho flint reduziu a eficiência alimentar dos animais, mas aumentou o peso da carcaça quente. A floculação aumentou o valor energético do cereal para tourinhos Nelore em dietas com alto teor de energia.

Influence of phytase and xylanase supplementation on growth performance and nutrient utilisation of broilers offered wheat-based diets

Individual and combined supplementation of phosphorus-adequate, wheat-based broiler diets with exogenous phytase and xylanase was evaluated in three experiments. The effects of the enzyme combination in lysine-deficient diets containing wheat and sorghum were more pronounced than those of the individual feed enzymes. The inclusion of phytase plus xylanase improved (p<0.05) weight gains (7.3%) and feed efficiency (7.0%) of broilers (7-28 days post-hatch) and apparent metabolisable energy (AME) by 0.76 MJ/kg DM. Phytase plus xylanase increased (p<0.05) the overall, apparent ileal digestibility of amino acids by 4.5% (0.781 to 0.816); this was greater than the responses to either phytase (3.6%; 0.781 to 0.809) or xylanase (0.7%; 0.781 to 0.784). Absolute increases in amino acid digestibility with the combination exceeded the sum of the individual increases generated by phytase and xylanase for alanine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, phenylalanine, threonine, tyrosine and valine. These synergistic responses may have resulted from phytase and xylanase having complementary modes of action for enhancing amino acid digestibilities and/or facilitating substrate access. The two remaining experiments were almost identical except wheat used in Experiment 2 had a higher phytate concentration and a lower estimated AME content than wheat used in Experiment 3. Individually, phytase and xylanase were generally more effective in Experiment 2, which probably reflects the higher dietary substrate levels present. Phytase plus xylanase increased (p<0.05) gains (15.4%) and feed efficiency (7.0%) of broiler chicks from 4-24 days post-hatch in Experiment 2; whereas, in Experiment 3, the combination increased (p<0.05) growth to a lesser extent (5.6%) and had no effect on feed efficiency. This difference in performance responses appeared to be 'protein driven' as the combination increased (p<0.05) nitrogen retention in Experiment 2 but not in Experiment 3; whereas phytase plus xylanase significantly increased AME in both experiments. In Experiments 2 and 3 the combined inclusion levels of phytase and xylanase were lower that the individual additions, which demonstrates the benefits of simultaneously including phytase and xylanase in wheat-based poultry diets.

Effect of granule morphology on breakage behaviour during compression

In the area of dry particle breakage, Discrete Element Method (DEM) simulations have been widely used to analyse the sensitivity of various physical parameters to the behaviour of agglomerates during breakage. This paper looks at the effect of agglomerate shape and structure on the mechanisms and extent of breakage of dry agglomerates under compressive load using DEM simulations. In the simulations, a spherical-shaped agglomerate produced within the DEM code is compared with an irregularly shaped agglomerate, whose structure is that of an actual granule that was characterised with X-ray microtomography (muCT). Both agglomerates have identical particle size distribution, coordination number and surface energy values, with only the agglomerate shape and structure differing between the two. The work here details the breakage behaviour with a number of traditional DEM output parameters (i.e., contact/cluster distributions) with showing vastly different behaviour between the two agglomerates. (C) 2004 Elsevier B.V. All rights reserved.

Phase separation, porous structure, and cure kinetics in aliphatic epoxy resin containing hyperbranched polyester

Thermosetting blends of an aliphatic epoxy resin and a hydroxyl-functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 4,4'-diaminodiphenylmethane (DDM) as the curing agent. The phase behavior and morphology of the DDM-cured epoxy/HBP blends with HBP content up to 40 wt% were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The cured epoxy/HBP blends are immiscible and exhibit two separate glass transitions, as revealed by DMA. The SEM observation showed that there exist two phases in the cured blends, which is an epoxy-rich phase and an HBP-rich phase, which is responsible for the two separate glass transitions. The phase morphology was observed to be dependent on the blend composition. For the blends with HBP content up to 10 wt%, discrete HBP domains are dispersed in the continuous cured epoxy matrix, whereas the cured blend with 40 wt% HBP exhibits a combined morphology of connected globules and bicominuous phase structure. Porous epoxy thermosets with continuous open structures on the order of 100-300 nm were formed after the HBP-rich phase was extracted with solvent from the cured blend with 40 wt% HBP. The DSC study showed that the curing rate is not obviously affected in the epoxy/HBP blends with HBP content up to 40 wt %. The activation energy values obtained are not remarkably changed in the blends; the addition of HBP to epoxy resin thus does not change the mechanism of cure reaction of epoxy resin with DDM. (c) 2006 Wiley Periodicals, Inc.

The effect of xylanase, phytase and lipase supplementation on the performance of broiler chickens fed a diet with a high level of rice bran.

Enzyme products did not have a significant effect (P>0.05) on weekly fed intake and weight gain of birds. But feed intake tended to drop and weight gain tended to increase in response to supplementation of the three enzymes. Weight gain of the birds was increased by 0.6% with lipase, 3.7% with phytase and 2.4% with xylanase. Xylanase had a marked effect (P

Statistical deconvolution of enthalpic energetic contributions to MHC-peptide binding affinity

Background - MHC Class I molecules present antigenic peptides to cytotoxic T cells, which forms an integral part of the adaptive immune response. Peptides are bound within a groove formed by the MHC heavy chain. Previous approaches to MHC Class I-peptide binding prediction have largely concentrated on the peptide anchor residues located at the P2 and C-terminus positions. Results - A large dataset comprising MHC-peptide structural complexes was created by re-modelling pre-determined x-ray crystallographic structures. Static energetic analysis, following energy minimisation, was performed on the dataset in order to characterise interactions between bound peptides and the MHC Class I molecule, partitioning the interactions within the groove into van der Waals, electrostatic and total non-bonded energy contributions. Conclusion - The QSAR techniques of Genetic Function Approximation (GFA) and Genetic Partial Least Squares (G/PLS) algorithms were used to identify key interactions between the two molecules by comparing the calculated energy values with experimentally-determined BL50 data. Although the peptide termini binding interactions help ensure the stability of the MHC Class I-peptide complex, the central region of the peptide is also important in defining the specificity of the interaction. As thermodynamic studies indicate that peptide association and dissociation may be driven entropically, it may be necessary to incorporate entropic contributions into future calculations.

Exoenzimas em rações de frangos de corte

The study aimed to evaluate performance, relative weight of the small intestine, digestibility and deposition of minerals in the bone of broilers supplemented with enzymatic complex (carbohydrases and phytase) in sorghum-based diets or sorghum and millet. In the experiments based of sorghum and sorghum and millet were used 912 day-old male and female Hubbard Flex chicks (50:50) were distributed in a completely randomized design in a 2x2 factorial arrangement (Feed Control base Sorghum (Contcs); FeedReducedbase Sorghum (RedS); Feed Control base sorghum + Enzymatic Complex (Contcs + Enz);. Feed reduced base sorghum + Enzymatic Complex (RedS + Enz) in the study of feed basis of sorghum and millet the design was similar (Feed Control base sorghum + millet ( ContSM); Reduced feed based on Millet + Sorghum (RedSM); Feed Control based Sorghum + Millet + EnzimaticComplex (ContSM + Enz); Reduced Feed base Sorghum+ Millet + Enzimatic Complex (RedSM + Enz). At 35 and 42 days of age were determined performance data: feed intake (CR), body weight (BW), feed conversion (FC), viability (VIAB), relative weight of the small intestine and deposition of minerals in the bone. The digestibility was evaluated sorghum grain size (crushed and whole) with and without exoenzimatico complex. They used 32 birds, eight birds per treatment, in periods from 17 to 21 (initial) and 31 to 35 days of age (fattening). The exoenzimático complex used in feed favored the weight gain results, feed conversion and bone mineralization when compared to a control diet not added to enzymes, demonstrating its effect on non-starch polysaccharides and phosphorus phytic present as anti-nutritional factors in these diets, increasing the digestibility and supply of metabolizable energy, essential amino acids, methionine and lysine and calcium and phosphorus for bone formation. It is concluded that a safe strategy for inclusion in feed is based on the reduction of energy levels, essential amino acids, methionine and lysine and calcium and phosphorus in the expected result of the constant activity of the enzymes of this exoenzimático complex.

Drying kinetics, biochemical and functional properties of products in convective drying of anchovy (Engraulis Anchoita) fillets

The aim of this work was to study the convective drying of anchovy (Engraulis anchoita) fillets and to evaluate the final product characteristics through its biochemical and functional properties. The drying temperatures were of 50, 60 and 70°C, and the fillet samples were dried with the skins down (with air flow one or the two sides) and skins up (with air flow one side). The drying experimental data were analyzed by Henderson–Pabis model, which showed a good fit (R2 > 0.99 and REQM < 0.05). The moisture effective diffusivity values ranged from 4.1 10–10 to 8.6 10–10 m2 s−1 with the skin down and 2.2 10–10 to 5.5 10–10 m2 s−1 with the skin up, and the activation energy values were 32.2 and 38.4 kJ mol−1, respectively. The product characteristics were significantly affected (p < 0.05) by drying operation conditions. The lower change was in drying at 60°C with air flow for two sides of the samples and skin up. In this condition, the product showed solubility 22.3%; in vitro digestibility 87.4%; contents of available lysine and methionine 7.21 and 2.64 g 100 g−1, respectively; TBA value 1.16 mgMDA kg−1; specific antioxidant activity was 1.91 mMDPPH g−1 min−1, and variation total color was 10.72.