Rumen function and digestion parameters associated with differences between sheep in methane emissions when fed chaffed lucerne hay

Abstract

An indoor experiment involving 10 rumen-cannulated Romney sheep was conducted in May and June 1998 at AgResearch Grasslands, Palmerston North, New Zealand, under restricted feeding conditions, in order to test the hypothesis that animal factors, in particular rumen fractional outflow rate (FOR) and rumen volume, have an influence on the between-sheep variation in methane (CH4) emission. Sheep were fed 2-hourly on chaffed lucerne hay. Following an acclimatization period of 21 days, the experiment lasted 16 days. Energy and nitrogen (N) balances were measured on days 1–6. Cr-EDTA marker was continuously infused into the rumen from day 9 to 16, and rumen contents emptied and sampled on days 13 and 16. Particulate and fluid FOR were estimated using feed lignin and Cr-EDTA, respectively. Daily CH4 production was measured by the sulphur hexafluoride tracer technique on days 2, 5, 6, 12 and 15 of the experiment.CH4 production (g/day) was positively correlated with the pool size of organic matter (OM) in the rumen (OM pool, g) (r=0·84, P=0·002), OM intake (OMI, g/day) (r=0·67, P=0·04), and the rumen fill (g, wet digesta) (r=0·76, P=0·01). Multiple regression analysis showed that CH4 production was best predicted (R2=0·88) as a function of OM pool and the molar % of butyrate; however, OM pool alone accounted for a large proportion (R2=0·71) of the variation in CH4 production.CH4 yield (% gross energy intake, % GEI) was negatively correlated with the particulate FOR (%/h) (r=−0·75, P=0·01) and buffering capacity of rumen fluid (mmol HCl) (r=−0·72, P=0·02), but positively correlated with the digestibility of cellulose (r=0·66, P=0·04). Multiple regression analysis showed that CH4 yield was best predicted as a function of particulate FOR, OMI (g/kg liveweight0·75) and the molar % of butyrate (R2=0·88). Particulate FOR alone explained a large proportion (R2=0·57) of the variation in CH4 yield. Particulate FOR was negatively correlated with rumen fill (r=−0·69, P=0·03) and digestibility of cellulose (r=−0·65, P=0·04).These results suggest that sheep with lower rumen particulate FOR (i.e. longer rumen retention times) had larger rumen fills and higher fibre digestibilities and CH4 yields. If rumen particulate FOR is to be used as a tool for CH4 mitigation, the repeatability of its relationship to CH4 emission must be assessed, preferably under grazing conditions.

Methane yield phenotypes linked to differential gene expression in the sheep rumen microbiome

“…Particle retention time in ruminants is known to be a heritable trait (Orskov et al 1988;Smuts et al 1995) and may explain at least some of the CH 4 yield variation observed in sheep (Pinares-Patiño et al 2003). Recently, CH 4 yield in sheep in Australia has been directly correlated with the retention time of feed particles and liquid and with the total amount of feed particles and rumen volume (Goopy et al 2013), further supporting this view.…”

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 gene-centric metagenomics is not low cost or high throughput, these results point to potential future proxy approaches using inexpensive gene chips. 5 the size of the rumen and its retention time are related to CH 4 emission (Pinares Patiño et al, 2003;Barnett et al, 2012;Goopy et al, 2014). Rumen volume was determined by X-ray computed tomography scanning in the study by Goopy et al (2014), which demonstrated that low-MeY sheep had smaller rumens.…”

Genome sequencing of rumen bacteria and archaea and its application to methane mitigation strategies

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