Positioning and number of nutritional levels in dose-response trials to estimate the optimal-level and the adjustment of the models

Souza, Fernando A.; Malheiros, Euclides Braga; Carneiro, Paulo Roberto Oliveira

doi:10.1590/0103-8478cr20130694

Cited by 4 publications

(3 citation statements)

References 10 publications

(8 reference statements)

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“…where y is dependent variable, and x is the content of DFRB. The optimal substitution level of corn by DFRB was predicted by quadratic regression equation as described by Souza et al [32]. Quadratic regression equation:…”

Section: Discussionmentioning

confidence: 99%

Effects of Increasing Levels of Defatted Rice Bran on Intestinal Physical Barrier and Bacteria in Finishing Pigs

Wang

et al. 2019

Animals

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The aims of this study were to assess the effects of increasing levels of DFRB as a replacement for corns on intestinal physical barrier function and bacteria of finishing pigs. A total of 35 castrated finishing pigs (age: 158.5 ± 2.0 d, initial body weight: 62.9 ± 0.8 kg) were randomly divided into five dietary treatments (seven replicates/treatment) for a 28-day experimental period, i.e., a control diet with basal diet, and four experimental diets in which maize was replaced by 7%, 14%, 21%, and 28% DFRB, respectively. The results showed that serum endotoxins concentration and diamine oxidase (DAO) activity were both increased (linear, p = 0.0004, 0.001, respectively) with DFRB level. However, compared with control group, serum endotoxins concentration and DAO activity were not different in pigs fed with 7% DFRB in the diet. There was a quadratic response in serum D-lactate concentration to the increased DFRB (quadratic, p = 0.021). In the cecum, thickness of the intestinal wall significantly increased with increasing levels of DFRB in the diets (linear, p = 0.033), while crypt depth/thickness of the intestinal wall ratio significantly decreased with increasing level of DFRB in the diets (linear, p = 0.043). In the jejunum, total bacteria, Escherichia coli, and Bifidobacterium all responded quadratically to increasing levels of DFRB in the diets (quadratic, p = 0.003, 0.001, 0.006, respectively). Additionally, there was no difference in Escherichia coli in pigs fed 0%, 7%, and 14% DFRB diets. In the colon, there were quadratic responses in C. perfringens to the increased DFRB (quadratic, p = 0.023). C. perfringens reduced as the DFRB concentration increased from 0% to 14% and then increased. When D-lactate, total bacteria, Escherichia coli, Bifidobacterium, and C. perfringens were considered, the optimal substitution level of DFRB were 12.00%, 11.84%, 7.50%, 8.92%, and 15.92%, respectively. In conclusion, 7% DFRB had a beneficial effect on intestinal wall thickness, Bifidobacterium and C. perfringens, and had no adverse effect on intestinal permeability and Escherichia coli.

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Section: Discussionmentioning

confidence: 99%

Effects of Increasing Levels of Defatted Rice Bran on Intestinal Physical Barrier and Bacteria in Finishing Pigs

Wang

et al. 2019

Animals

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“…The optimization of the dosage of Fenton reagents has been a target for several organic molecules. Experiments using the plateau segmented linear regression model and the plateau segmented quadratic regression model, which use the plateau response technique to models that have minimal levels of regression (Peixoto et al, 2011;Souza et al 2014). Thus, the objective of this study was to evaluate the effect of H2O2/Fe²+ concentrations in Fenton after WC system in sewage treatment for removal of organic matter.…”

Section: Introductionmentioning

confidence: 99%

Domestic wastewater treatment with Fenton and Constructed Wetlands system

Marcionilio,

Gadêlha,

Carvalho

et al. 2024

Multidisciplinary Perspectives: Integrating Knowledge

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Alternative forms of domestic sewage treatments, such as Constructed Wetlands (WC) systems, are efficient and environmentally friendly. This effect can be intensified by associating two treatments to reduce the pollutant load, in this work, combined the Fenton reaction after a WC system for the removal of Organic Matter (OM). The experimental assay was carried out in a 5 x 5 factorial arrangement, with the factors beingH2O2 and Fe²+ at concentrations at both 0, 25, 50, 75 and 100 %, and the variable response was OM at UV 254nm. The data were submitted to exploratory analysis, considering the effects of the factors and their interactions, performing the analysis of variance and statistical models Linear, Linear Plateau, quadratic and quadratic Plateau. There was an interaction between the factors, unfolding Fe²+ within H2O2, it was found that in all H2O2 concentrations, the plateau model was the one that best fitted. While in the unfolding H2O2 within Fe²+ it was found that in concentrations up to 50% of Fe²+ the quadratic model was better adjusted, while in the highest concentrations (75 and 100%) it was the plateau. Modeling demonstrated that the optimal dosage for this study is 25% H2O2 (250 mg L-1) / 33% Fe3+ (165 mg L-1), removing 92.75% OM.

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“…The linear Quadratic and the nonlinear Spillman-Mitscherlich model are commonly applied to analyze dose-response relationship with independent errors in a large variety of fields including environmental sciences, biology, public health, and agricultural sciences (de Souza et al [7]; Pinheiro et al [23]; WHO [37]). The model parameters are usually estimated by means of least squares under the assumptions of fixed parameters and errors that are independently and normally distributed with constant variances (Lopez-Bellido et al [17]; Sain and Jauregui [28]).…”

Section: Introductionmentioning

confidence: 99%

Bayesian Estimation of Random Parameter Models of Responses with Normal and Skew-t Distibutions Evidence from Monte Carlo Simulation

Masjkur

Folmer

2018

JIMS

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Random parameter models have been found to outperform xed pa-rameter models to estimate dose-response relationships with independent errors. Amajor restriction, however, is that the responses are assumed to be normally andsymmetrically distributed. The purpose of this paper is to analyze Bayesian infer-ence of random parameter response models in the case of independent responseswith normal and skewed, heavy-tailed distributions by way of Monte Carlo simu-lation. Three types of Bayesian estimators are considered: one applying a normal,symmetrical prior distribution, a second applying a Skew-normal prior and, a thirdapplying a Skew-t-distribution. We use the relative bias (RelBias) and Root MeanSquared Error (RMSE) as valuation criteria. We consider the commonly applied lin-ear Quadratic and the nonlinear Spillman-Mitscherlich dose-response models. Onesimulation examines the performance of the estimators in the case of independent,normally and symmetrically distributed responses; the other in the case of indepen-dent responses following a heavy-tailed, Skew-t-distribution. The main nding isthat the estimator based on the Skew-t prior outperforms the alternative estima-tors applying the normal and Skew-normal prior for skewed, heavy-tailed data. Fornormal data, the Skew-t prior performs approximately equally well as the Skew-normal and the normal prior. Furthermore, it is more ecient than its alternatives.Overall, the Skew-t prior seems to be preferable to the normal and Skew-normal fordose-response modeling.

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Positioning and number of nutritional levels in dose-response trials to estimate the optimal-level and the adjustment of the models

Cited by 4 publications

References 10 publications

Effects of Increasing Levels of Defatted Rice Bran on Intestinal Physical Barrier and Bacteria in Finishing Pigs

Effects of Increasing Levels of Defatted Rice Bran on Intestinal Physical Barrier and Bacteria in Finishing Pigs

Domestic wastewater treatment with Fenton and Constructed Wetlands system

Bayesian Estimation of Random Parameter Models of Responses with Normal and Skew-t Distibutions Evidence from Monte Carlo Simulation

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