The transit of external markers throughout the ruminant digestive tract: 1. The fitting quality of models to marker profiles in feces using an information-theoretic approach

Júnior, Nardele Moreno Rohem; Silva, Marcelo Cabral da; Abreu, Matheus Lima Corrêa; Oliveira, Jhone Gleison de; Glória, Leonardo Siqueira; Tedeschi, L. O.; Vieira, Ricardo Augusto Mendonça

doi:10.1016/j.anifeedsci.2020.114407

Cited by 4 publications

(3 citation statements)

References 56 publications

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“…The model fitted with the variance function in equation 17 challenges the fitted one based on the traditional homoscedastic assumption described by equation 16. Parameter ω is the intercept of the VarConstPower function (equation 18), which allowed modeling the variances when |g(Θ m , t ijk )| = 0 or equal to a baseline or background value, and when the variance scales to the mean for |g(Θ m , t ijk )| > 0 or greater than a baseline value (Pinheiro and Bates, 2000;Rohem Júnior et al, 2020;Vieira et al, 2020). The fit of the model with the first-order autoregressive correlation structure given by equation 19 challenges the traditional assumption of independent time records on the same subject (Vonesh, 2012); this was accomplished by fitting the corCAR1 function of nlme package (Pinheiro and Bates, 2000).…”

Section: Model Fitting: First-step Predictionmentioning

confidence: 99%

“…The development of tools from theories of nonlinear mixed-effects models and generalized linear mixed-effects models (Pinheiro and Bates, 2000;Littell et al, 2006;Vonesh, 2012;Stroup, 2013) has provided instruments to describe several nonlinear phenomena in animal science (Zanton and Heinrichs, 2009;Strathe et al, 2010;Albertini et al, 2012;Araujo et al, 2015;Vieira et al, 2018Vieira et al, , 2020Rohem Júnior et al, 2020). The information-theoretic approach (I-T) provides the elements for evaluating the quality of fit of models by aiming at their predictive powers (Buckland et al, 1997;Sober, 2002;Burnham and Anderson, 2004;Burnham et al, 2011a).…”

Section: Introductionmentioning

confidence: 99%

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The geometry of the lactation curve based on Wood's equation: a two-step prediction

Oliveira

Sant’Anna

Lourenço

et al. 2020

Revista Brasileira De Zootecnia

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-Lactation records from cows of the southwestern Paraná state, Brazil, form the dataset of this study. We applied the information-theoretic approach to evaluate the ability of the nonlinear Wood, Brody, Dijkstra, and Gamma functions to fit to these data by employing a two-step technique based on nonlinear mixed-effects models and generalized linear mixed-effects models. Wood's equation was fitted with the combination of a first-order autoregressive correlation structure and a variance function to account for heteroscedasticity. This version was the best choice to mimic lactation records. Some geometric attributes of Wood's model were deduced, mainly the ascending specific rate from parturition to peak milk yield and the descending specific rate as a measure of the lactation persistence of the milk yield at peak production. Breed and parity order of the cows were assumed as fixed effects to obtain a reliable model fitting process. Regardless of breed, first-order parity cows had greater persistency than their older counterparts, and the greater the ascending rate of milk yield from the parturition to the peak, the sharper the decrease in milk yield post-peak; therefore, the rates (absolute values) of ascending and descending phases correlated positively. Nonetheless, the actual estimated values of the descending phase rates are negative. Wood's equation was flexible enough to mimic either concave-and convex-shaped lactation profiles. The correlations between both peak milk yield and random estimates for β with total milk yield per lactation were positive. However, peak milk yield might not be the only variable used for ranking cows; the total milk yield integrates all information of the lactation profile through the estimated parameters of Wood's equation.

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Section: Model Fitting: First-step Predictionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The geometry of the lactation curve based on Wood's equation: a two-step prediction

Oliveira

Sant’Anna

Lourenço

et al. 2020

Revista Brasileira De Zootecnia

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“…Dynamic digestion models not only predict the nutritional value of feeds, dietary changes, microbial populations, and livestock physiological conditions, can also be detected the limiting factors of digestion process (Gregorini, Provenza, Villalba, Beukes, & Forbes, 2018;Bannink, van Lingen, Ellis, France, & Dijkstra, 2016;Reed, Arhonditsis, France, & Kebreab, 2016). Various models have been proposed to describe the digestion and passage of feed in the digestive system of ruminants (Rochen et al, 2020;Palangi & Macit, 2019;Dijkstra, Bannink, Bosma, Lantinga, & Reijs, 2018). The amount of digestion is a function of the time it stops in the digestive tract (Oberson, Probst, & Schlegel, 2019;Lopes et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Validation of in situ disappearance curves utilizing mathematical models for incubating fish meal and cottonseed mea

Palangi¹,

Besharati²

2020

Semina: Ciênc. Agrár.

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our mathematical models were used to describe the ruminal disappearance of dry matter (DM) and crude protein (CP) of fish meal and cottonseed meal. Results of DM degradability particularity showed that all the models fitted well (R2 > 0.95), however, considering that values below 0 or above 100 are not biologically justified in ruminal degradability, they are not acceptable. The models I and II were accepted to ruminal DM degradability of fish meal and cottonseed meal data. Only models I and II were successfully fitted to CP degradability of fish meal (R2 > 0.96), and the I, II and III models were acceptable to ruminal CP degradability of cottonseed meal (R2 > 0.98). In terms of effective degradability (ED) of DM and CP, model II generated higher values than other models. To appreciate fully the role of mathematical modelling in the biological sciences, it is necessary to consider the nature of feeds that evaluated and to review the types of models that may be constructed.

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The transit of external markers throughout the ruminant digestive tract: 2. The estimation of fiber digestibility, ruminoreticular fill, and related biases

Vieira

Júnior²,

Abreu³

et al. 2020

Animal Feed Science and Technology

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The transit of external markers throughout the ruminant digestive tract: 1. The fitting quality of models to marker profiles in feces using an information-theoretic approach

Cited by 4 publications

References 56 publications

The geometry of the lactation curve based on Wood's equation: a two-step prediction

The geometry of the lactation curve based on Wood's equation: a two-step prediction

Validation of in situ disappearance curves utilizing mathematical models for incubating fish meal and cottonseed mea

The transit of external markers throughout the ruminant digestive tract: 2. The estimation of fiber digestibility, ruminoreticular fill, and related biases

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