Estimating the extent of degradation of ruminant feeds from a description of their gas production profiles observed<i>in vitro</i>: comparison of models

Dhanoa, M. S.; López, Secundino; Dijkstra, J.; Davies, David R.; Sanderson, Ruth; Williams, Barbara A.; Sileshi, Z.; France, J.

doi:10.1017/s0007114500000179

Cited by 53 publications

(43 citation statements)

References 29 publications

(69 reference statements)

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“…Adicionalmente, Fondevila & Barrios (2001) mencionaram que os modelos multicompartimentais são mais adequados quando se utilizam um número muito grande de leituras, tal como ocorre nos sistemas automatizados, e que isso não ocorre quando o número de leituras é limitado, porém, de acordo com Pell et al (2000) n>16, leituras mais freqüentes na fase inicial são suficientes para proporcionar um ajuste adequado. No entanto, alguns autores (Dhanoa et al, 2000;France et al, 2000) recomendaram a utilização de modelos unicompartimentais devido a interpretação mecanicista, em preferência a puramente empírica dos modelos multicompartimentais.…”

Section: Resultsunclassified

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

Mello

Magalhães

Breda

et al. 2008

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi identificar entre os modelos Brody, Von Bertalanffy, Gompertz, France, Logístico, Logístico modificado e Logístico bicompartimental, aquele que apresenta maior qualidade de ajuste à curva de produção cumulativa de gases em silagens de girassol e milho. Os critérios adotados foram: coeficiente de determinação, quadrado médio do resíduo, análise gráfica das curvas observadas e estimadas, análise gráfica de dispersão dos resíduos estudentizados, erro percentual médio, eficiência relativa e número de iterações para atingir a convergência. Os modelos Brody, France e Logístico bicompartimental apresentaram os maiores valores de coeficiente de determinação em ambos os substratos, e a diferença entre eles pode ser considerada desprezível. Estes modelos apresentaram, também, os menores valores de quadrado médio do resíduo em silagens de girassol, e a diferença entre eles foi considerada desprezível. Os modelos Brody e France apresentaram menor quadrado médio do resíduo em silagens de milho. Todos os modelos apresentaram dispersão positiva dos resíduos em ambos os substratos após 144 horas de incubação. O modelo Brody apresentou menor erro percentual médio e número de iterações em ambos os substratos. Os modelos Logístico bicompartimental e France apresentaram maior eficiência relativa, respectivamente, em silagens de girassol e milho. Assim, o modelo Logístico bicompartimental apresenta maior qualidade de ajuste à curva de produção de gases em silagens de girassol e milho.Termos para indexação: cinética, in vitro, modelo matemático, modelos não-lineares. Models for fit of gas production in sunflower and corn silagesAbstract -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...

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Section: Resultsunclassified

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

Mello

Magalhães

Breda

et al. 2008

Pesq. agropec. bras.

View full text Add to dashboard Cite

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“…In fitting the present models the lag phase can simply be deleted from the equation if it does not significantly improve the fit of the curve, except in the case of the generalized Mitscherlich where a lag, albeit small, is needed to prevent a mathematical discontinuity in m at zero time. There seems little to choose between the present models biologically and mathematically, so choice of best model should be made on the basis of fitting criteria (see Dhanoa et al 2000).…”

Section: Discussionmentioning

confidence: 99%

Estimating the extent of degradation of ruminant feeds from a description of their gas production profiles observedin vitro:derivation of models and other mathematical considerations

et al. 2000

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Equations to describe gas production profiles, obtained using manual or automated systems for in vitro fermentation of ruminant feeds, were derived from first principles by considering a simple three-pool scheme. The pools represented were the potentially degradable and undegradable feed fractions, and accumulated gases. The equations derived and investigated mathematically were the generalized Mitscherlich, generalized Michaelis-Menten, Gompertz, and logistic. They were obtained by allowing the fractional rate of degradation to vary with time. The equations permit the extent of ruminal degradation (hence the supply of microbial protein to the duodenum) to be evaluated, thus linking the gas production technique to animal production. Rumen: Gas production: Mathematical models

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“…As observed in Figure 1, the highest gas volume in BF showed that F was more degradable in the rumen to provide more fermentable substrate, given the fact that the gas produced is directly proportional to the rate at which the substrate is degraded [17]. The minimum gas production in FPSB might be due to the prevention of substrate availability for bacteria by prill fat or the possible toxicity of microorganisms.…”

Section: Discussionmentioning

confidence: 87%

In Vitro Yield of Microbial-N from Fermentation of Glucogenic and Lipogenic Diets Provided by Different Sources of Rumen Degradable Amino Acids

Eyni¹,

Mesgaran²,

Vakili³

et al. 2017

J Vet Sci Technol

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This experiment was conducted to evaluate the effects of different sources of rumen degradable amino acids, soybean meal versus a commercial source of hydrolyzed cottonseed cake with low molecular weight (Fortid ® ), on the in vitro ruminal fermentation responses and the microbial nitrogen yield of glucogenic (n=8) and lipogenic (n=8) diets. An in vitro gas production technique was used to determine the differences in microbial nitrogen yield of the diets. Sources of grain including barely and corn were used in the glucogenic diets as grinded or steam flaked, while in the lipogenic diets, corn silage, sugar beet pulp, linseed and prill fat were used to provide the energy needed for rumen fermentation. The experiment was a randomized design including two types of diets × two sources of rumen degradable amino acids factorial arrangement. The gas produced from the fermentable fraction (b) was higher for the lipogenic diets containing corn silage and F than those for the others. The fraction (b) and microbial nitrogen to diet nitrogen ratio were greater (p<0.05) for Fortid ® versus soybean meal. The true substrate digestibility of glucogenic diets were significantly higher (p<0.05) compared to those of lipogenic diets. Both the grain sources used as steam flaked caused an increase in the rate of gas produced (c) and microbial nitrogen to diet nitrogen ratio. There were significant interactions (p<0.005) of the type of diets with either soybean meal or Fortid ® on microbial nitrogen to diet nitrogen. The results indicated that pre-hydrolyzed protein sources which are rich in low molecular weight peptides may be considered as candidates to improve rumen feed fermentation and microbial nitrogen production with both glucogenic and lipogenic diets. This conclusion was arrived at from the different patterns of action of soybean meal and Fortid ® in the present in vitro rumen fermentation responses.

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Estimating the extent of degradation of ruminant feeds from a description of their gas production profiles observedin vitro: comparison of models

Cited by 53 publications

References 29 publications

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

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

Estimating the extent of degradation of ruminant feeds from a description of their gas production profiles observedin vitro:derivation of models and other mathematical considerations

In Vitro Yield of Microbial-N from Fermentation of Glucogenic and Lipogenic Diets Provided by Different Sources of Rumen Degradable Amino Acids

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