A mechanistic model of pH and gas exchanges in the rumen and its in vitro application

Serment, Amélie; Sauvant, Daniel

doi:10.3920/978-90-8686-712-7_16

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…Volatile fatty acid production (notably propionate), growth of microbes, fatty acid biohydrogenation, reductive acetogenesis, nitrate and sulfur reduction have been described in the literature as other potential sinks of molecular H 2 . This type of in vitro study is useful for building or assessing mechanistic models of rumen functioning, such as the model of Serment and Sauvant which describes pH and gas exchanges in a syringe. The measurements of gas composition and VFA profile presented here allowed the completion of such an approach by assessing the partition of carbon and hydrogen.…”

Section: Discussionmentioning

confidence: 99%

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates

et al. 2015

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Section: Discussionmentioning

confidence: 99%

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates

et al. 2015

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“…This role for ammonia of intermediate substrate between degradation and assimilation of nitrogen by microorganisms was also emphasized by Al-Rabbat et al ( 1971 ) and Tamminga ( 1979 ). It could be also modeled, as shown by the mechanistic model proposed on pea seed fractions data by Serment and Sauvant ( 2010 ). The rate of NH 3 production was more constant and lower for the PCF flour, which degraded more slowly.…”

Section: Discussionmentioning

confidence: 99%

Influence of grinding on the nutritive value of peas for ruminants: comparison between in vitro and in situ approaches

Giger-Reverdin

Maaroufi

Chapoutot

et al. 2014

Food Science & Nutrition

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In ruminant nutrition, peas are characterized by high protein solubility and degradability, which impair its protein value estimated by the official in situ method. Grinding can be used as a technological treatment of pea seeds to modify their nutritional value. The aim of this study was to compare the in situ method with an in vitro method on the same pea either in a coarse pea flour form (PCF) or in a ground pea fine flour form (PFF) to understand the effect of grinding. Both forms were also reground (GPCF and GPFF). PCF presented a lower rate of in vitro degradation than PFF, and more stable fermentation parameters (pH, ammonia, soluble carbohydrates) even if gas production was higher for the PCF after 48 h of incubation. In situ dry matter and protein degradation were lower for PCF than those for PFF; these differences were more marked than with the in vitro method. Reground peas were very similar to PFF. The values for pea protein digestible in the intestine (PDI) were higher for PCF than those for PFF. This study points out the high sensitivity of the in situ method to grinding. The study needs to be validated by in vivo measurements.

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Dynamic sensitivity analysis of a mathematical model describing the effect of the macroalgaeAsparagopsis taxiformison rumen fermentation and methane production underin vitrocontinuous conditions

Blondiaux,

Kiessé,

Eugène

et al. 2024

Preprint

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Ruminants plays an important role in global warming by emitting enteric methane (CH4) through the degradation of feeds by the rumen microbiota. To better understand the dynamics fermentation outputs, including methane and volatile fatty acids (VFA) production, mathematical models have been developed. Sensitivity analysis (SA) methods quantify the contribution of model input parameters (IP) to the variation of an output variable of interest. In animal science, SA are usually conducted in static condition. In this work, we hypothesized that including the dynamic aspect of the rumen fermentation to SA can be useful to inform on optimal experimental conditions aimed at quantifying the key mechanisms driving CH4and VFA production. Accordingly, the objective of this work was to conduct a dynamic SA of a rumen fermentation model underin vitrocontinuous conditions (close to the realin vivoconditions). Our model case study integrates the effect of the macroalgaeAsparagopsis taxiformis(AT) on the fermentation. AT has been identified as a potent CH4inhibitor via the presence of bromoform, an anti-methanogenic compound. We implemented two SA methods. We computed Shapley effects and full and independent Sobol indices over time for quantifying the contribution of 16 IPs to CH4(mol/h) and VFA (mol/l) variation. Our approach allows to discriminate the 3 contribution types of an IP to output variable variation (individual, via the interactions and via the dependence/correlation). We studied three diet scenarios accounting for several doses of AT relative to Dry Matter (DM): control (0% DM of AT), low treatment (LT: 0.25% DM of AT) and high treatment (HT: 0.50% DM of AT). Shapley effects revealed that hydrogen (H2) utilizers microbial group via its Monod H2affinity constant highly contributed (> 50%) to CH4variation with a constant dynamic over time for control and LT. A shift on the impact of microbial pathways driving CH4variation was revealed for HT. IPs associated with the kinetic of bromoform utilization and with the factor modeling the direct effect of bromoform on methanogenesis were identified as influential on CH4variation in the middle of fermentation. Whereas, VFA variation for the 3 diet scenarios was mainly explained by the kinetic of fibers degradation, showing a high constant contribution (> 30%) over time. In addition, the Sobol indices indicated that interactions between IPs played a role on CH4variation, which was not the case of VFA variation. However, these results are dependent on the way interactions are represented in the model. The simulations computed for the SA were also used to analyze prediction uncertainty. It was related to the dynamic of dry matter intake (DMI, g/h), increasing during the high intake activity periods and decreasing when the intake activity was low. Moreover, CH4(mol/h) simulations showed a larger variability than VFA simulations, suggesting that the reduction of the uncertainty of IPs describing the activity of the H2utilizers microbial group is a promising lead to reduce the overall model uncertainty. Our results highlighted the dynamic nature of the influence of metabolic pathways on CH4productions under an anti-methanogenic treatment. SA tools can be further exploited to design optimal experiments studying rumen fermentation and CH4mitigation strategies. These optimal experiments would be useful to build robust models that can guide the development of sustainable nutrition strategies.

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A mechanistic model of pH and gas exchanges in the rumen and its in vitro application

Abstract: absen

Cited by 3 publications

References 13 publications

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates

Influence of grinding on the nutritive value of peas for ruminants: comparison between in vitro and in situ approaches

Dynamic sensitivity analysis of a mathematical model describing the effect of the macroalgaeAsparagopsis taxiformison rumen fermentation and methane production underin vitrocontinuous conditions

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