A Model to Interpret Gas Accumulation Profiles Associated with In Vitro Degradation of Ruminant Feeds

France, J.; Dhanoa, M. S.; Theodorou, M. K.; Lister, S.J.; Davies, David R.; Isac, Dragoş Lucian

doi:10.1006/jtbi.1993.1109

Cited by 368 publications

(278 citation statements)

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“…Therefore, there are large differences in the FRD among the LE 0 , MM and GM models (Figure 3), resulting from different underlying assumptions included in the models. The LE 0 , MM and GM models are developed on the basis of the conception of microbial growth and substrate degradation (Wang et al, 2011), enzyme reactions (Groot et al, 1996) and substrate surface and complete invasion by microbes (France et al, 1993), respectively. It is widely accepted that FRG and the FRD are different concepts Ló pez et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Curve fitting The LE 0 (Wang et al, 2011), the EXP LAG (Schofield et al, 1994), the GM (France et al, 1993) and the MM (Groot et al, 1996) models were compared for their ability in revealing fermentation processes from the gas production curve (Table 2 and Figure 3). The NLREG version 5.4 software (Sherrod, 1995) was used to calculate fermentation parameters with the four models tested.…”

Section: Logistic-exponential (Le) Modelmentioning

confidence: 99%

“…Fractional rate of degradation (FRD) is defined as the rate of degradation (RD) divided by the weight of degradable substrate and changes with the alteration of hydration of particle, microbial attachment and microbial numbers (France et al, 1993 and. So, comparing with the RD, the FRD is not related to -Present address: Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, P. R. China.…”

Section: Introductionmentioning

confidence: 99%

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Deriving fractional rate of degradation of logistic-exponential (LE) model to evaluate early in vitro fermentation

Wang

Sun

Tang

et al. 2013

Animal

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Water-soluble components of feedstuffs are mainly utilized during the early phase of microbial fermentation, which could be deemed an important determinant of gas production behavior in vitro. Many studies proposed that the fractional rate of degradation (FRD) estimated by fitting gas production curves to mathematical models might be used to characterize the early incubation for in vitro systems. In this study, the mathematical concept of FRD was developed on the basis of the Logistic-Exponential (LE) model, with initial gas volume being zero (LE 0 ). The FRD of the LE 0 model exhibits a continuous increase from initial (FRD 0 ) toward final asymptotic value (FRD F ) with longer incubation time. The relationships between the FRD and gas production at incubation times 2, 4, 6, 8, 12 and 24 h were compared for four models, in addition to LE 0 , Generalization of the Mitscherlich (GM), c th order Michaelis-Menten (MM) and Exponential with a discrete LAG (EXP LAG ). A total of 94 in vitro gas curves from four subsets with a wide range of feedstuffs from different laboratories and incubation periods were used for model testing. Results indicated that compared with the GM, MM and EXP LAG models, the FRD of LE 0 model consistently had stronger correlations with gas production across the four subsets, especially at incubation times 2, 4, 6, 8 and 12 h. Thus, the LE 0 model was deemed to provide a better representation of the early fermentation rates. Furthermore, the FRD 0 also exhibited strong correlations (P , 0.05) with gas production at early incubation times 2, 4, 6 and 8 h across all four subsets. In summary, the FRD of LE 0 model provides an alternative to quantify the rate of early stage incubation, and its initial value could be an important starting parameter of rate.Keywords: mathematical models, rate of gas production, logistic-exponential model, in vitro fermentation ImplicationsThe fractional rate of degradation (FRD) of LE 0 model generally had high correlation with gas production at 2, 4, 6 and 8 h across all four subsets tested, and thus provides a good alternative to reveal the rate of early stage in vitro fermentation. The FRD of LE 0 model would have an implication in quantifying the rate of fermentation and evaluating digestion efficiency of feedstuffs in the rumen, as ruminal retention time of feedstuffs is short. However, further studies are needed to testify whether a higher FRD leads to a higher nutritive value (e.g. volatile fatty acid profile, microbial protein synthesis and feedstuff digestibility) for ruminants.

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Section: Discussionmentioning

confidence: 99%

Section: Logistic-exponential (Le) Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deriving fractional rate of degradation of logistic-exponential (LE) model to evaluate early in vitro fermentation

Wang

Sun

Tang

et al. 2013

Animal

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“…For faba beans, maize and peas, the k d remained the same despite the marked reduction of the washout fraction when using the new rinsing method, whereas for barley, oats and wheat the k d decreased compared with the washing machine rinsing method. These observations would suggest that the washout fraction of starch has a lower degradation rate than the non-washout fraction, which seems to be unrealistic based on the physical state of this fraction (France et al, 1993). An alternative explanation for this decrease in degradation rate is the process of particle size reduction during the incubation in combination with particulate matter loss, which was different for the two rinsing methods.…”

Section: Discussionmentioning

confidence: 99%

“…The degradation rate of this washout fraction cannot be measured in situ and therefore in various feed evaluation systems assumptions on this degradation rate are made to be able to estimate the fermentability of the washout fraction (Offner et al, 2003;van Duinkerken et al, 2011;Volden, 2011). The washout fraction of starch is relatively large and highly variable between feeds (Offner et al, 2003;de Jonge et al, 2013) and is generally considered to be rapidly degradable based on theoretical assumptions about the degradation of small particles (France et al, 1993) and comparison between in situ and in vivo data (van Duinkerken et al, 2011). However, the assumption that material washed out of nylon bags is rapidly and completely degraded in the rumen is not supported by in vitro gas production results (Yang et al, 2005;Cone et al, 2006;Stevnebø et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Estimation of the in situ degradation of the washout fraction of starch by using a modified in situ protocol and in vitro measurements

Jonge

Laar

Dijkstra

2015

Animal

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The in situ degradation of the washout fraction of starch in six feed ingredients (i.e. barley, faba beans, maize, oats, peas and wheat) was studied by using a modified in situ protocol and in vitro measurements. In comparison with the washing machine method, the modified protocol comprises a milder rinsing method to reduce particulate loss during rinsing. The modified method markedly reduced the average washout fraction of starch in these products from 0.333 to 0.042 g/g. Applying the modified rinsing method, the fractional degradation rate ( k d ) of starch in barley, oats and wheat decreased from on average 0.327 to 0.144 h −1 whereas for faba beans, peas and maize no differences in k d were observed compared with the traditional washing machine rinsing. For barley, maize and wheat, the difference in non-fermented starch in the residue between both rinsing methods during the first 4 h of incubation increased, which indicates secondary particle loss. The average effective degradation of starch decreased from 0.761 to 0.572 g/g when using the new rinsing method and to 0.494 g/g when applying a correction for particulate matter loss during incubation. The in vitro k d of starch in the non-washout fraction did not differ from that in the total product. The calculated ratio between the k d of starch in the washout and non-washout fraction was on average 1.59 and varied between 0.96 for oats and 2.39 for maize. The fractional rate of gas production was significantly different between the total product and the non-washout fraction. For all products, except oats, this rate of gas production was larger for the total product compared with the non-washout fraction whereas for oats the opposite was observed. The rate of increase in gas production was, especially for grains, strongly correlated with the in vitro k d of starch. The results of the present study do not support the assumption used in several feed evaluation systems that the degradation of the washout fraction of starch in the rumen is much faster than that of the non-washout fraction.Keywords: particulate matter loss, in situ protocol, in vitro, rumen degradability, starch ImplicationThis study showed that the fractional degradation rate (k d ) of starch of the washout fraction was lower than generally assumed. In addition, the rinsing method affected the k d caused by particulate matter loss. The effect of both observations on the effective degradation of starch varied between feed ingredients, and can therefore change the ranking in nutritive value.

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The Effect of Extrusion Conditions on the Fermentability of Wheat Straw and Corn Silage

Williams

Poel

Bôer

et al. 1997

J. Sci. Food Agric.

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A Model to Interpret Gas Accumulation Profiles Associated with In Vitro Degradation of Ruminant Feeds

Cited by 368 publications

References 0 publications

Deriving fractional rate of degradation of logistic-exponential (LE) model to evaluate early in vitro fermentation

Deriving fractional rate of degradation of logistic-exponential (LE) model to evaluate early in vitro fermentation

Estimation of the in situ degradation of the washout fraction of starch by using a modified in situ protocol and in vitro measurements

The Effect of Extrusion Conditions on the Fermentability of Wheat Straw and Corn Silage

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