Nucleotides, β-glucans, ascorbic acid, α-tocoferol, and different concentrations of a vitamin-mineral premix promote growth of Nile tilapia juveniles

ABSTRACT Feed additives, such as β-glucans, nucleotides, ascorbic acid (vitamin C), and α-tocopherol (vitamin E) can improve fish immunity and contribute to enhanced zootechnical performance of the fish. This study aimed to evaluate the effect of different concentrations of vitamin- mineral premix with or without the inclusion of an immunostimulant boost (β-glucans, nucleotides and vitamins C and E) on the zootechnical performance, hemato-immunological parameters, histological changes, and survival of Nile tilapia juveniles. To this end, isocaloric and isoproteic diets were prepared with three different concentrations of vitamin-mineral premix (1.0, 1.5, and 2.0 kg ton-1); additionally, the effects of 4% immunostimulant boost in the diet were examined considering six diets (without the immunostimulant boost: 0.1%, 0.15%, and 0.2%, and with the immunostimulant boost: 0.1% I, 0.15% I, and 0.2% I). We used 24 experimental units, each including 15 fish. Nile tilapia juveniles (1.88 g±0.25) were fed for 50 d with supplemented diets. Further, zootechnical indexes; histological changes in the liver, spleen, and intestine; intestinal morphology; and hemato-immunological parameters were evaluated. The fish that received supplementation showed higher zootechnical values, compared to those that did not receive the supplementation of immunostimulant reinforcement. Weight gain (30.45g±3.06), daily weight gain (0.60g±0.06), final weight (32.41g±3.15) and feed conversion (0.95±0.06) were higher in tilapia fed with an inclusion concentration of 0.2%. Hematological parameters were not affected by either the pre-mix concentrations or the booster of the immunostimulant. There was an increase in the number of intestinal folds, length of the fold, total area and number of goblet cells in the group supplemented with immunostimulant reinforcement. Supplementation with the immunostimulant promoted growth and improved intestinal morphology and immunological parameters of Nile tilapia juveniles

Fabricación de recubrimientos de alta resistencia por LMD para estampación en caliente

EUSKERA: Beroko estanpazio prozesuak txapa konformaketaren fabrikazio teknologia da, deformatu beharreko materiala aurreberotu ostean pieza konformatu eta tenplatu egiten da; non trokelaren gune aktiboak higadura latzak jasaten dituen. Balio gehigarri altuko trokel hauen bizi zikloa luzatzeko, takoak kolpeak jasateko ijeztutako altzairu harikor batekin fabrikatzea proposatzen da, gainetik laser prozesu gehigarriaren bidez (LMD) errendimendu altuko estaldura bat gehituko zaio bere gogortasunari esker abrasio bidezko higadura minimizatzen dituena. Horretarako gradiente funtzional (FGM) bidezko estaldura egitea planteatzen da, material ezberdinak konbinatuz, piezaren konposizioa aldatu ahala barne propietateak aldatuko dituena.CASTELLANO: El proceso de estampación en caliente es una tecnología de fabricación de conformado de chapas, en los que se calienta previamente el material a deformar y se procede al conformado y temple de la pieza; donde la parte activa de los troqueles sufre un gran desgaste. Para aumentar la vida de estos útiles de alto valor añadido, se propone fabricar los tacos con un material base de acero laminado dúctil que pueda resistir los continuos impactos de la estampación, sobre el que se aportará mediante aporte por láser (LMD) un recubrimiento de alto rendimiento que gracias a su alta dureza minimice el desgaste por abrasión. Para ello se plantea realizar un recubrimiento con gradiente funcional (FGM), combinando distintos materiales, dotando así a la pieza de distintas propiedades a medida que varía la composición.ENGLISH: The hot stamping process is a manufacturing technology for sheet metal forming, in which the material to be deformed is heated beforehand and the part is formed and hardened; where the active part of the dies suffers a great deal of wear. In order to increase the life of these high added value tools, it is proposed to manufacture the blocks with a ductile laminated steel base material that can resist the continuous impacts of the stamping, on which a high performance coating will be provided by means of a laser contribution (LMD) which, thanks to its high hardness, minimizes wear by abrasion. For this purpose, a coating with a functional gradient (FGM) is proposed, combining different materials, thus providing the part with different properties as the composition varies