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Effect of protease supplementation on apparent ileal crude protein and amino acid digestibility of over-processed soybean meals in broilers

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Journal of Animal Science and Biotechnology 2022年第6期13卷 1810-1817页

作者： Sergio Salazar-Villanea maikol astúa-ureña Allison Masís-Montoya Juan I.Herrera-Muñoz Catalina Salas-Durán Escuela de Zootecnia Universidad de Costa RicaSan JoséCosta Rica Centro de Investigación en Nutrición Animal Universidad de Costa RicaSan JoséCosta Rica

Background: Nutritional value of proteins in feed ingredients can be negatively affected by hydrothermal processing, which causes large variation in the bioavailability of amino acids(AA) and negatively affects animal productive performance. Supplementation of exogenous proteases could increase the rate of digestion of damaged proteins, thereby increasing overall AA digestibility and bioavailability. The aim was to determine the effect of exogenous protease supplementation on the apparent ileal digestibility(AID) of crude protein(CP) and AA of soybean meals(SBM) with different degrees of hydrothermal processing in broilers.Methods: The experiment involved a 3 × 2 factorial arrangement, with SBM processing time(commercial SBM or autoclaved for 30 or 60 min at 120 ℃) and protease supplementation(not supplemented and supplemented) as factors. Protease was included at three times the recommended dose(0.06%) and the experimental diets were fed from 15 to 21 d.Results: The interaction between the effects of SBM processing and protease supplementation was significant for the AID of CP(P = 0.01), Trp(P = 0.01), Gly(P = 0.03) and Pro(P = 0.03), and also for the average daily gain(P = 0.01)and feed conversion ratio(P = 0.04). Increasing the processing time of SBM decreased(P < 0.0001) the AID of all amino acids, whilst the effect of protease supplementation was only significant for the AID of Phe(P = 0.02) and Tyr(P = 0.01).Conclusions: Exogenous protease supplementation at three times the commercial dose does not seem to offset the negative effects of hydrothermal processing of SBM on the apparent ileal digestibility of CP and amino acids or performance of broilers. Whilst positive numerical improvements of digestibility and performance(ADG and FCR)were noticed with protease supplementation at relatively mild processing levels, negative results were obtained with the harsh-processed meals.

关键词： Amino acids Apparent ileal digestibility Broilers Exogenous protease

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Evaluation of integration methods for hybrid simulation of complex structural systems through collapse

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Earthquake Engineering and Engineering Vibration 2017年第4期16卷 745-759页

作者： maikol Del Carpio R. M.Javad Hashemi Gilberto Mosqueda KPFF Consulting Engineers Los AngelesCA 90045USA Faculty of Science Engineering and TechnologySwinburne University of TechnologyMelbourneVIC 3122Australia Department of Structural Engineering University of CaliforniaSan DiegoCA 92093USA

This study examines the performance of integration methods for hybrid simulation of large and complex structural systems in the context of structural collapse due to seismic excitations. The target application is not necessarily for real-time testing, but rather for models that involve large-scale physical sub-structures and highly nonlinear numerical models. Four case studies are presented and discussed. In the first case study, the accuracy of integration schemes including two widely used methods, namely, modified version of the implicit Newmark with fixed-number of iteration （iterative） and the operator-splitting （non-iterative） is examined through pure numerical simulations. The second case study presents the results of 10 hybrid simulations repeated with the two aforementioned integration methods considering various time steps and fixed-number of iterations for the iterative integration method. The physical sub-structure in these tests consists of a single-degree-of-freedom （SDOF） cantilever column with replaceable steel coupons that provides repeatable highly- nonlinear behavior including fracture-type strength and stiffness degradations. In case study three, the implicit Newmark with fixed-number of iterations is applied for hybrid simulations of a 1：2 scale steel moment frame that includes a relatively complex nonlinear numerical substructure. Lastly, a more complex numerical substructure is considered by constructing a nonlinear computational model of a moment frame coupled to a hybrid model ofa 1：2 scale steel gravity frame. The last two case studies are conducted on the same porotype structure and the selection of time steps and fixed number of iterations are closely examined in pre-test simulations. The generated unbalance forces is used as an index to track the equilibrium error and predict the accuracy and stability of the simulations.

关键词： Hybrid simulation collapse integration methods unbalance forces stability and accuracy numerical errors

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