Navegando por Autor "Abreu, Matheus Lima Corrêa"

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Evaluation of mathematical models to describe gas production kinetics of some tropical and temperate forages
(Brazilian Journal of Animal Science, 2020-06-01) Oliveira, Jhone Gleison de; Henrique, Douglas Sampaio; Abreu, Matheus Lima Corrêa; Fluck, Ana Carolina; Mayer, Lilian Regina Rothe; Costa, Olmar Antônio Denardin; Atoji-Henrique, Katia
Our objective was to identify the best fit mathematical models for in vitro gas production kinetics using rumen fluid and forage plants commonly used in ruminant feed to obtain better estimates of parameters that describe the rumen fermentation. Four mathematical models were tested, two unicompartmental (M1 = first order, M2 = Gompertz) and two bicompartmental (M3 = M1 + M2; M4 = M2 + M2). Two temperate grasses were evaluated, as well as four tropical grasses and three temperate forage legumes. The fit of the models was verified by the corrected Akaike information criterion (AICcr ) and the difference among AICcr values (Δr ), likelihood probability (Wr ), and relative likelihood (ERr ). Temperate forages reached maximum gas production between 48 and 72 h. In the tropical forages, it occurred only after 72 h. In profiles in which M3 was the best choice, the values of parameters Vf 1 were higher than those of Vf 2 , and k1 values were higher than k2 values. The only exception was for Tifton 85 profile, whose Vf 2 value was higher than Vf 1 . The model M3 has a better fit for tropical forages with higher fiber content and lower levels of nonfibrous carbohydrates and crude protein. The model M1 has a better fit for forage with higher nonfibrous carbohydrate contents and low lignin content
Simulation of diets for dairy goats and growing doelings using nonlinear optimization procedures
(Revista Brasileira de Zootecnia, 2016-08-03) Glória, Leonardo Siqueira; Abreu, Matheus Lima Corrêa; Rocha, Norberto Silva; Oliveira, Tadeu Silva de; Gomes, Raphael dos Santos; Rohem Júnior, Nardele Moreno; Bendia, Laila Cecília Ramos; Fernandes, Alberto Magno
The objective of this study was to simulate total dry matter intake and cost of diets optimized by nonlinear programming to meet the nutritional requirements of dairy does and growing doelings. The mathematical model was programmed in a Microsoft Excel(r) spreadsheet. Increasing values of body mass and average daily weight gain for growing doelings and increasing body mass values and milk yield for dairy does were used as inputs for optimizations. Three objective functions were considered: minimization of the dietary cost, dry matter intake maximization, and maximization of the efficiency of use of the ingested crude protein. To solve the proposed problems we used the Excel(r) Solver(r) algorithm. The Excel(r) Solver(r) was able to balance diets containing different objective functions and provided different spaces of feasible solutions. The best solutions are obtained by least-cost formulations; the other two objective functions, namely maximize dry matter intake and maximize crude protein use, do not produce favorable diets in terms of costs.