Estimation of Stoichiometric Parameters for Rumen Fermentation of Roughage and Concentrate Diets

Murphy, Michael R.; Baldwin, R.L.; Koong, L. J.

doi:10.2527/jas1982.552411x

Cited by 185 publications

(180 citation statements)

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“…Stoichiometric coefficients derived in this study for NDF (66:17:14:3 for C2:C3:C4:minor VFA, respectively) are in good agreement with the average coefficients reported previously by other authors for the cell wall component (64:14:18:4 on average by Murphy et al, 1982;Bannink et al, 2006;Sveinbjö rnsson et al, 2006). In contrast, for starch, our results showed a highly propionic pattern (41:44:12:3) compared to the coefficients reported by the other authors (on average 53:23:18:6), but our coefficients are highly consistent with those reported for amylolytic bacteria (48:45:5:1) by Nagorcka et al (2000) who set up separate coefficients for bacteria and protozoa.…”

Section: Determination Of Stoichiometric Coefficientssupporting

confidence: 92%

“…In current mechanistic models (Baldwin et al, 1987;Dijkstra et al, 1992;Pitt et al, 1996), separate coefficients for roughage and concentrate diets are considered (Murphy et al, 1982;Bannink et al, 2006;Sveinbjö rnsson et al, 2006) and their use requires accurate knowledge of five fermented substrates (soluble carbohydrates, starch, hemicellulose, cellulose and protein), although the precision of the analytical determination of some of these substrates (i.e. hemicellulose) remains questionable.…”

Section: Determination Of Stoichiometric Coefficientsmentioning

confidence: 99%

“…Consequently, our approach is less dependent on the assumptions made for the derivation of the stoichiometric estimates. In addition, compared to previous studies in which the cell wall components were dissociated between cellulose and hemicellulose (Murphy et al, 1982;Bannink et al, 2006), we considered NDF as a unique entity, because ruminal digestion of NDF is frequently reported and accurately measured in the publications. Consequently, we propose in this study several coefficient sets depending on the measured digested fractions in the rumen (only OM and NDF or OM, NDF and starch or OM, NDF, starch and CP).…”

Section: Determination Of Stoichiometric Coefficientsmentioning

confidence: 99%

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In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

Nozière

Glasser

Sauvant

2011

Animal

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Despite their major contribution to the energy supply of ruminants, the production of volatile fatty acids (VFA) in the rumen is still poorly predicted by rumen models. We have developed an empirical approach, based on the interpretation of large bibliographic databases gathering published in vivo measurements of ruminal VFA production rate (PR), rates of duodenal and faecal digestion and molar percentages of VFA in the rumen. These databases, covering a wide range of intake levels and dietary composition, were studied by meta-analysis using within-experiment models. We established models to quantify response laws of total VFA-PR and individual VFA molar percentages in the rumen to variations in intake level and dietary composition. The rumen fermentable organic matter (RfOM) intake, estimated from detailed knowledge of the chemical composition of diets according to INRA Feed Tables, appears as an accurate explanatory variable of measured total VFA-PR, with an average increment of 8.03 6 0.64 mol total VFA/kg RfOM intake. Similar results were obtained when total VFA-PR was estimated from measured apparent RfOM (total VFA-PR/RfOM averaging 8.3 6 1.2 mol/kg). The VFA molar percentages were related to dry matter intake and measured digestible organic matter (OM), digestible NDF and rumen starch digestibility, with root mean square error of 1.23, 1.45, 0.88 and 0.41 mol/100 mol total VFA for acetate, propionate, butyrate and minor VFA, respectively, with no effect of pH on the residuals. Stoichiometry coefficients were calculated from the slopes of the relationships between individual VFA production (estimated from measured apparent RfOM and individual VFA molar percentages) and measured fermented fractions. Coefficients averaged, respectively, 66, 17, 14 and 3 mol/100 mol for NDF; 41, 44, 12 and 4 mol/100 mol for starch; and 46, 35, 13 and 6 mol/100 mol for crude protein. Their use to predict VFA molar percentages appear relevant for most dietary conditions, that is, when the digested NDF/digested OM ratio exceeded 0.12. This study provides a quantitative review on VFA yield in the rumen. It contributes to the development of feed evaluation systems based on nutrient fluxes.

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Section: Determination Of Stoichiometric Coefficientssupporting

confidence: 92%

Section: Determination Of Stoichiometric Coefficientsmentioning

confidence: 99%

Section: Determination Of Stoichiometric Coefficientsmentioning

confidence: 99%

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In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

Nozière

Glasser

Sauvant

2011

Animal

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“…With decreased retention time, a lower proportion of feed is fermented in the rumen and with less complete digestion, relatively more easily fermentable parts of the CHO are digested (Huhtanen et al, 2006), which are normally considered to be least methanogenic (Beauchemin et al, 2008). It is well documented that CHO composition affects fermentation pattern (Murphy et al, 1982;Bannink et al, 2006;Nozière et al, 2010). Measured data for rumen digestibility and rumen VFA profile were used in the present study and the aforementioned effects of CHO composition on fermentation pattern should therefore already have been accounted for in the model calculations.…”

Section: Discussionmentioning

confidence: 99%

“…The most common approach to estimate the amount of VFA produced in the rumen is to estimate the amount of individual nutrients (protein, carbohydrates (CHO) and glycerol of fat origin) that is truly digested in the rumen, and subsequently calculate glucose units available from these nutrients for fermentation to VFA. Specific coefficient values are derived from the literature to estimate the proportion of individual VFA from fermented nutrients (Murphy et al, 1982). It is widely accepted that rumen fermentation pattern is closely related to CH 4 production due to changes in the H 2 balance such that high acetate and butyrate production enhance CH 4 production, whereas high propionate production reduces CH 4 emission (e.g.…”

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confidence: 99%

Methane production and diurnal variation measured in dairy cows and predicted from fermentation pattern and nutrient or carbon flow

Brask

Weisbjerg

Hellwing

et al. 2015

Animal

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Many feeding trials have been conducted to quantify enteric methane (CH 4 ) production in ruminants. Although a relationship between diet composition, rumen fermentation and CH 4 production is generally accepted, the efforts to quantify this relationship within the same experiment remain scarce. In the present study, a data set was compiled from the results of three intensive respiration chamber trials with lactating rumen and intestinal fistulated Holstein cows, including measurements of rumen and intestinal digestion, rumen fermentation parameters and CH 4 production. Two approaches were used to calculate CH 4 from observations: (1) a rumen organic matter (OM) balance was derived from OM intake and duodenal organic matter flow (DOM) distinguishing various nutrients and (2) a rumen carbon balance was derived from carbon intake and duodenal carbon flow (DCARB). Duodenal flow was corrected for endogenous matter, and contribution of fermentation in the large intestine was accounted for. Hydrogen (H 2 ) arising from fermentation was calculated using the fermentation pattern measured in rumen fluid. CH 4 was calculated from H 2 production corrected for H 2 use with biohydrogenation of fatty acids. The DOM model overestimated CH 4 /kg dry matter intake (DMI) by 6.1% ( R 2 = 0.36) and the DCARB model underestimated CH 4 /kg DMI by 0.4% ( R 2 = 0.43). A stepwise regression of the difference between measured and calculated daily CH 4 production was conducted to examine explanations for the deviance. Dietary carbohydrate composition and rumen carbohydrate digestion were the main sources of inaccuracies for both models. Furthermore, differences were related to rumen ammonia concentration with the DOM model and to rumen pH and dietary fat with the DCARB model. Adding these parameters to the models and performing a multiple regression against observed daily CH 4 production resulted in R 2 of 0.66 and 0.72 for DOM and DCARB models, respectively. The diurnal pattern of CH 4 production followed that of rumen volatile fatty acid (VFA) concentration and the CH 4 to CO 2 production ratio, but was inverse to rumen pH and the rumen hydrogen balance calculated from 4 × (acetate + butyrate)/2 × (propionate + valerate). In conclusion, the amount of feed fermented was the most important factor determining variations in CH 4 production between animals, diets and during the day. Interactions between feed components, VFA absorption rates and variation between animals seemed to be factors that were complicating the accurate prediction of CH 4 . Using a ruminal carbon balance appeared to predict CH 4 production just as well as calculations based on rumen digestion of individual nutrients.Keywords: modelling methane, VFA, enteric fermentation, carbon, dairy cow Implications Methane (CH 4 ) is a potent greenhouse gas that arises from feed fermentation in the rumen and large intestine of ruminant animals. The quantity of CH 4 depends on daily feed intake, feed chemical composition and feed rumen digestibility. Therefore, the present paper was ...

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Degradation of starch in feed concentrates by enzymes, rumen fluid and rumen enzymes

Cone

1991

J Sci Food Agric

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A B S T R A C TThe degradation of starch from various feedstujji was investigated with rumen fluid, a-amylase, pancreutin and a freeze-dried, cell-free preparation of rumen fluid. Rumen fluid was taken from either a hay-fed cow or a concentrate-fed cow. I t was shown that incubations with rumen fluid at a constant p H of 6.5 gave a higher degradation of starch than those with a decreasing p H . The degree of starch degradation varied widely for the 21 feedstufs investigated. Sorghum, maize and millet degraded slowly whereas tapioca showed fast degradation. Processed ,feedstujJs showed a higher level of degradation than unprocessed ones. The use of enzymes did not allow an accurate prediction of starch degradation by rumen fluid. However, this was made possible by the use of a ,fLeeze-dried, cell-Jiee preparation of rumen fluid. Scanning electron microscopic observations showed that for the degradation of starch granules additional enzymes, present in rumen ,fluid, are necessary.

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Estimation of Stoichiometric Parameters for Rumen Fermentation of Roughage and Concentrate Diets

Cited by 185 publications

References 33 publications

In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

Methane production and diurnal variation measured in dairy cows and predicted from fermentation pattern and nutrient or carbon flow

Degradation of starch in feed concentrates by enzymes, rumen fluid and rumen enzymes

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