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

Abstract

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 ...

Diurnal Dynamics of Gaseous and Dissolved Metabolites and Microbiota Composition in the Bovine Rumen

“…These hourly averages are generally in line with the results in this study (minimum 5 mmol/h; maximum 200 mmol/h; peak at 0.5 h). The fitted CH 4 emission profiles in the present study are in line with Brask et al (2015) who reported the highest average hourly emission from dairy cows in the second hour after feeding, whereas the highest average hourly emission was observed in the third hour after feeding by Olijhoek et al (2016). Rooke et al (2014) and Olijhoek et al (2016) observed an increase in CH 4 emission by a factor of two after feeding, which is similar to the increase observed in the present study.…”

Effect of Feeding System on Enteric Methane Emissions from Individual Dairy Cows on Commercial Farms

“…Notably, between 21:00 and 00:59, emissions of cows on a PMR with grazing system remained high and similar to the previous time period, whereas emissions of cows on a PMR feeding system were reduced compared to the previous time period. The diurnal pattern is dependent on the time, frequency, and amount of food consumed [14], and has no overall influence on average daily CH 4 emissions [16,17], which is consistent with the lack of an overall difference in emissions between feeding systems in the current study (log-transformed mean of 0.3 mg/L for PMR and 0.36 mg/L for PMR with grazing, SED = 0.14, P > 0.05). The precise timing of feed allocation at each farm was not known, but would add to the interpretation of the results.…”

“…Crompton et al [14] identified the relationship between the time of feeding and CH 4 emissions, with a rapid increase in emissions after an animal consumes food followed by a gradual decline. Several studies have observed a diurnal pattern to CH 4 emissions from ruminant livestock [9,14,15], which is affected by feed allowance and feeding frequency [14], with no overall influence on average daily CH 4 yield [16,17].…”

Invited review: Large-scale indirect measurements for enteric methane emissions in dairy cattle: A review of proxies and their potential for use in management and breeding decisions

“…Although this relationship holds in some studies (e.g., Chung et al, 2011;Van Zijderveld et al, 2010), treatment effects on CH 4 emissions and VFA proportions did not correspond in about half of the studies (e.g., Beauchemin et al, 2009;Brask et al, 2015;Supplementary Table S1; https://doi.org/10.3168/jds.2016-12030). Overall, the relations between CH 4 emission and both VFA and pH are variable in the literature and not as straightforward as expected from theory.…”

“…A combination of rumen VFA and microbiome estimates might be more informative, even though, as far as we are aware, there are not yet sufficient studies with detailed microbiome profiles and rumen metabolite measurements to evaluate this proposition. Additionally, the absorption of the different VFA from the rumen is differentially affected by rumen pH so that rumen VFA proportions measured in rumen fluid do not necessarily provide a good basis for estimating VFA proportions actually produced in the rumen (Brask et al, 2015). It may be that a combination of rumen VFA proportions and pH, perhaps with some modeling, might be more informative.…”