Mathematical models that describe gas production are widely used to estimate the rumen degradation digestibility and kinetics. The present study presents a method to generate models by combining existing models and to propose the von Bertalanffy-Gompertz two-compartment model based on this method. The proposed model was compared with the logistic two-compartment one to indicate which best describes the kinetic curve of gas production through the semi-automated in vitro technique from different pinto peanut cultivars. The data came from an experiment grown and harvested at the Far South Animal Sciences station (Essul) in Itabela, BA, Brazil and gas production was read at 2, 4, 6, 8, 10, 12, 14, 17, 20, 24, 28, 32, 48, 72, and 96 h after the start of the in vitro fermentation process. The parameters were estimated by the least squares method using the iterative Gauss-Newton process in the software R version 3.4.1. The best model to describe gas accumulation was based on the adjusted coefficient of determination, residual mean squares, mean absolute deviation, Akaike information criterion, and Bayesian information criterion. The von Bertalanffy-Gompertz two-compartment model had the best fit to describe the cumulative gas production over time according to the methodology and conditions of the present study.

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Generation of models from existing models composition: An application to agrarian sciences.

. The palm tree jucara (Euterpe edulis Mart) is considered one of the most important and threatened native species in the Atlantic Forest. The search for jucara seeds (Euterpe edulis Martius) has increased, generating a need for technologies favorable to their production, quality and conservation. The aim of this study was to describe the seed germination patterns of 45 jucara accessions by using a nonlinear model to examine the behavior of these patterns and select superior genotypes. After clustering 45 jucara accessions into four groups, four nonlinear models, namely, the logistic, Gompertz, von Bertalanffy and Weibull models, were tested based on their fit for each group of accessions. The Gompertz model presented the best fit to describe the germination growth curve of E. edulis seeds. Groups 3 and 4 presented the highest daily germination rates and were considered the most vigorous. Analysis of deviance was performed, revealing genetic variability among the genotypes in terms of seed germination and vigor. It was possible to find a nonlinear model that best explained our data, and this model may also be a promising model for other palm tree species. It is possible to select genotypes based on the characters we analyzed, due to the elevated genetic variability.

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Euterpe edulis seed germination parameters and genotype selection

Objetivou-se com esta pesquisa avaliar as silagens de 23 hibridos de sorgo por meio da tecnica in vitro semiautomatica de producao de gases. Foi utilizado o delineamento inteiramente ao acaso, com 23 tratamentos e tres repeticoes, sendo os tratamentos as silagens de hibridos de sorgo. Os hibridos foram cultivados na estacao experimental do Instituto Nacional do Semiarido (INSA), no municipio de Campina Grande - PB. A producao de gases foi estimada por intermedio do modelo logistico bicompartimental, ajustado as curvas de producao cumulativa de gases. Com relacao ao volume final de carboidratos fibrosos (VfCF), houve efeito de hibrido (P<0,05), com resultados variando de 105,99 a 144,53mL/g de MS. Os valores de taxa de degradacao dos carboidratos fibrosos (KdCF) variaram (P<0,05), e o hibrido 866041 apresentou o maior resultado 0,015h-1. Os valores de volume final total (VfT) variaram (P<0,05), e os hibridos 870085, Volumax e XBS 60329 apresentaram maiores (P<0,05) valores de VfT em relacao aos demais. Pela analise multivariada, foram formados seis grupos distintos. O grupo 2, composto pelos hibridos 22 (Volumax) e 23 (XBS60329), apresentou os maiores valores medios para os volumes de gas, tanto para os carboidratos fibrosos quanto para os nao fibrosos. O grupo 4, composto pelo hibrido 1 (866005), apresentou as menores medias para volume de gas produzido e o maior lag time (3,15 horas). Todos os hibridos estudados apresentam potencial para ensilagem, de acordo com a cinetica de fermentacao ruminal.

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Cinética de fermentação ruminal in vitro de silagens de híbridos de sorgo

The objective of this study was to determine the adjustment quality of non-linear models and estimate the growth parameters and body chemical composition of a meat-type quail strain (Coturnix coturnix coturnix) and two laying quail strains (Coturnix coturnix japonica), designated yellow and red. The study used 1500 quail, not sexed, distributed in a completely randomized design with three treatments and five repetitions. The experimental period was from 1-42 days of age. The birds were raised in a conventional system [...]

https://www.rbz.org.br/wp-content/uploads/articles_xml/1806-9290-rbz-47-e20170244/1806-9290-rbz-47-e20170244.pdf

Adjustment of nonlinear models and growth parameters and body nutrient deposition in meat-type and laying quail.

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Method to generate growth and degrowth models obtained from combinations of existing models applied to agrarian sciences

The aim of this work was to identify among the Brody, Von Bertalanffy, Gompertz, France, Logistic, Modified logistic and Dual-pool logistic models, the one that presents the highest quality of fit for cumulative gas production curve in sunflower and corn silages. The quality of fit was evaluated by coefficient of determination, residual mean square, graphic analysis of the observed and estimated curves, graphic analysis of dispersion of the studentized residual, average percentage error, relative efficiency and number of iteractions to converge. Brody, France and Dual-pool logistic models showed the largest values of coefficient of determination in both substrates, and the difference among them was considered worthless. They also showed the smallest values of residual mean square in sunflower silages, being the difference among them considered worthless. Brody and France models presented smaller residual mean square in corn silages. All the models showed positive dispersion of the residual in both substrates after 144 hours of incubation. The Brody model showed smaller average percentage error and number of iterations in both substrates. The Dual-pool logistic and France models showed higher relative efficiency, respectively, in sunflower and corn silages. Thus, the Dual-pool logistic model showed higher quality of fit to the gas production curve in sunflower and corn silages.

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Renius Mello

Papers

Modelos para ajuste da produção de gases em silagens de girassol e milho