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Effect of altering ruminal pH by dietary buffer supplementation on methane emissions from sheep fed forage rape

  • X. Z. Sun (a1) (a2), R. Harland (a2) and D. Pacheco (a2)


Low methane (CH4) emissions from sheep fed forage rape (Brassica napus) might be related to low ruminal pH value. In this study, sodium carbonate (Na2CO3: SC) was supplemented to the diet to alter ruminal pH for evaluation of its role in CH4 emissions from sheep fed forage rape. Fourteen intact and eight fistulated Romney sheep were adapted to forage rape over 32 days and then randomly allocated to one of two groups: diets supplemented with SC or not (control). Methane emissions were measured from intact sheep in seven experimental periods. In parallel, ruminal pH and fermentation characteristics were assessed using the fistulated sheep. In the first (P01) and the second (P02) periods, none of the sheep received SC to examine the baseline CH4 emissions. The P01 period was used as a covariate for analysis of gas emission measurements in subsequent measurement periods. Sodium carbonate was offered at 5% of the forage DM in P03 and P04, increased to 8% in P05 and P06 to assess the effect of pH increase on CH4 emissions and stopped in P07 to assess if the CH4 emissions reverted to values similar to those measured before the supplementation started. Methane yield (g/kg forage DM intake) was similar for the sheep in both groups during P02 and P03, but sheep supplemented with SC in the diet emitted 36%, 49% and 30% more CH4 per unit of forage DM intake than those in the control group during P04, P05 and P06, respectively. Emissions returned to similar levels when SC supplementation was ceased in P07. Ruminal pH was 0.412 to 0.565 units higher in SC supplemented sheep than for the control group during the SC treatment periods. Based on the lack of an immediate response in CH4 emissions to the supplementation of SC in P03, the positive responses in P04 to P06 and the rapid disappearance of the response after supplementation with SC stopped in P07, we propose a new hypothesis that ruminal pH effects on CH4 emissions are possibly through medium-term changes in microbial and methanogenic communities in the rumen, rather than a direct, short-term impact on methanogens per se. In conclusion, SC supplemented to the forage rape diet of sheep increased rumen pH, leading to an increase in CH4 emissions. Low ruminal pH in sheep fed forage rape explains, at least partially, the reported low CH4 emissions from sheep fed with this forage crop.


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Aschenbach, JR, Penner, GB, Stumpff, F and Gäbel, G 2011. Ruminant nutrition symposium: role of fermentation acid absorption in the regulation of ruminal pH. Journal of Animal Science 89, 10921107.
Australian Agricultural Council 1990. Feeding standards for Australian livestock: ruminants. CSIRO Publications, Sydney, NSW, Australia.
Barry, TN 2013. The feeding value of forage brassica plants for grazing ruminant livestock. Animal Feed Science and Technology 181, 1525.
Beauchemin, KA, Kreuzer, M, O’Mara, F and McAllister, TA 2008. Nutritional management for enteric methane abatement: a review. Australian Journal of Experimental Agriculture 48, 2127.
Blaxter, KL and Clapperton, JL 1965. Prediction of the amount of methane produced by ruminants. British Journal of Nutrition 19, 511522.
Bougouin, A, Ferlay, A, Doreau, M and Martin, C 2018. Effects of carbohydrate type or bicarbonate addition to grass silage-based diets on enteric methane emissions and milk fatty acid composition in dairy cows. Journal of Dairy Science 101, 60856097.
Buddle, BM, Denis, M, Attwood, GT, Altermann, E, Janssen, PH, Ronimus, RS, Pinares-Patiño, CS, Muetzel, S and Wedlock, ND 2011. Strategies to reduce methane emissions from farmed ruminants grazing on pasture. Veterinary Journal 188, 1117.
Clark, H 2013. Nutritional and host effects on methanogenesis in the grazing ruminant. Animal 7 (suppl. 1), 4148.
Cruywagen, CW, Taylor, S, Beya, MM and Calitz, T 2015. The effect of buffering dairy cow diets with limestone, calcareous marine algae, or sodium bicarbonate on ruminal pH profiles, production responses, and rumen fermentation. Journal of Dairy Science 98, 55065514.
Deng, Y-Y, Ruan, W-Q, Yu, L and Huang, Y-B 2018. The effect of pH adjustment on hydrolytic bacteria and methanogens during rumen fluid derived anaerobic digestion of rice straw. Journal of Agro-Environment Science 37, 813819.
Dijkstra, J, Ellis, JL, Kebreab, E, Strathe, AB, López, S, France, J and Bannink, A 2012. Ruminal pH regulation and nutritional consequences of low pH. Animal Feed Science and Technology 172, 2233.
Enemark, JMD 2008. The monitoring, prevention and treatment of sub-acute ruminal acidosis (SARA): a review. Veterinary Journal 176, 3243.
Goopy, JP, Donaldson, A, Hegarty, R, Vercoe, PE, Haynes, F, Barnett, M and Oddy, VH 2014. Low-methane yield sheep have smaller rumens and shorter rumen retention time. British Journal of Nutrition 111, 578585.
Hammond, KJ, Burke, JL, Koolaard, JP, Muetzel, S, Pinares-Patiño, CS and Waghorn, GC 2013. Effects of feed intake on enteric methane emissions from sheep fed fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) forages. Animal Feed Science and Technology 179, 121132.
Hammond, KJ, Pacheco, D, Burke, JL, Koolaard, JP, Muetzel, S and Waghorn, GC 2014. The effects of fresh forages and feed intake level on digesta kinetics and enteric methane emissions from sheep. Animal Feed Science and Technology 193, 3243.
Hellwing, ALF, Brask, M, Lund, P and Weisbjerg, MR 2012. Effect of carbohydrate source and rumen pH on enteric methane from dairy cows. In Emissions of Gas and Dust from Livestock (ed. Hassouna, M and Guingand, N), pp. 206209. INRA, Rennes, France.
Hristov, AN, Kebreab, E, Niu, M, Oh, J, Bannink, A, Bayat, AR, Boland, TM, Brito, AF, Casper, DP, Crompton, LA, Dijkstra, J, Eugene, M, Garnsworthy, PC, Haque, N, Hellwing, ALF, Huhtanen, P, Kreuzer, M, Kuhla, B, Lund, P, Madsen, J, Martin, C, Moate, PJ, Muetzel, S, Munoz, C, Peiren, N, Powell, JM, Reynolds, CK, Schwarm, A, Shingfield, KJ, Storlien, TM, Weisbjerg, MR, Yanez-Ruiz, DR and Yu, Z 2018. Symposium review: uncertainties in enteric methane inventories, measurement techniques, and prediction models. Journal of Dairy Science 101, 66556674.
Hristov, AN, Oh, J, Firkins, JL, Dijkstra, J, Kebreab, E, Waghorn, GC, Makkar, HPS, Adesogan, AT, Yang, W, Lee, C, Gerber, PJ, Henderson, B and Tricarico, JM 2013. SPECIAL TOPICS-Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options. Journal of Animal Science 91, 50455069.
Hünerberg, M, McGinn, SM, Beauchemin, KA, Entz, T, Okine, EK, Harstad, OM and McAllister, TA 2015. Impact of ruminal pH on enteric methane emissions. Journal of Animal Science 93, 17601766.
Janssen, PH 2010. Influence of hydrogen on rumen methane formation and fermentation balances through microbial growth kinetics and fermentation thermodynamics. Animal Feed Science and Technology 160, 122.
Knight, T, Ronimus, RS, Dey, D, Tootill, C, Naylor, G, Evans, P, Molano, G, Smith, A, Tavendale, M, Pinares-Patiño, CS and Clark, H 2011. Chloroform decreases rumen methanogenesis and methanogen populations without altering rumen function in cattle. Animal Feed Science and Technology 166–167, 101112.
Krause, KM and Oetzel, GR 2006. Understanding and preventing subacute ruminal acidosis in dairy herds: a review. Animal Feed Science and Technology 126, 215236.
Lambert, MG, Abrams, SM, Harpster, HW and Jung, GA 1987. Effect of hay substitution on intake and digestibility of forage rape (Brassica napus) fed to lambs. Journal of Animal Science 65, 16391646.
Lana, RP, Russell, JB and Van Amburgh, ME 1998. The role of pH in regulating ruminal methane and ammonia production. Journal of Animal Science 76, 21902196.
Ministry for the Environment 2018. New Zealand’s greenhouse gas inventory 1990–2016. Ministry for the Environment, Wellington, New Zealand.
Moate, P, Wiiliams, SRO, Deighton, MH, Hannah, MC, Ribaux, BE, Morris, GL, Jacobs, JL and Wales, WJ 2019. Effects of feeding wheat or corn and of rumen fistulation on milk production and methane emissions of dairy cows. Animal Production Science 59, 891905.
Moate, PJ, Williams, SRO, Jacobs, JL, Hannah, MC, Beauchemin, KA, Eckard, RJ and Wales, WJ 2017. Wheat is more potent than corn or barley for dietary mitigation of enteric methane emissions from dairy cows. Journal of Dairy Science 100, 71397153.
Pacheco, D, Waghorn, GC and Janssen, PH 2014. Decreasing methane emissions from ruminants grazing forages: a fit with productive and financial realities? Animal Production Science 54, 11411154.
Pinares-Patiño, CS, Hunt, C, Martin, R, West, J, Lovejoy, P and Waghorn, GC 2014. New Zealand ruminant methane measurement centre. In Technical manual on respiration chamber design (ed. Pinares-Patiño, CS and Waghorn, GC), pp. 928. Ministry of Agriculture and Forestry, Wellington, New Zealand.
Pinares-Patiño, CS, Ulyatt, MJ, Lassey, KR, Barry, TN and Holmes, CW 2003. Rumen function and digestion parameters associated with differences between sheep in methane emissions when fed chaffed lucerne hay. Journal of Agricultural Science 140, 205214.
Ramin, M and Huhtanen, P 2013. Development of equations for predicting methane emissions from ruminants. Journal of Dairy Science 96, 24762493.
Russell, JB and Chow, JM 1993. Another theory for the action of ruminal buffer salts: decreased starch fermentation and propionate production. Journal of Dairy Science 76, 826830.
Staples, CR and Lough, DS 1989. Efficacy of supplemental dietary neutralizing agents for lactating dairy cows. A review. Animal Feed Science and Technology 23, 277303.
Sun, X, Henderson, G, Cox, F, Molano, G, Harrison, SJ, Luo, D, Janssen, PH and Pacheco, D 2015a. Lambs fed fresh winter forage rape (Brassica napus L.) emit less methane than those fed perennial ryegrass (Lolium perenne L.), and possible mechanisms behind the difference. PLOS ONE 10, e0119697.
Sun, XZ, Hoskin, SO, Zhang, GG, Molano, G, Muetzel, S, Pinares-Patiño, CS, Clark, H and Pacheco, D 2012b. Sheep fed forage chicory (Cichorium intybus) or perennial ryegrass (Lolium perenne) have similar methane emissions. Animal Feed Science and Technology 172, 217225.
Sun, XZ, Pacheco, D and Luo, DW 2016. Forage brassica: a feed to mitigate enteric methane emissions? Animal Production Science 56, 451456.
Sun, XZ, Sandoval, E and Pacheco, D 2015b. Effects of forage rape inclusion level in the diet on methane emissions from sheep. Proceedings of the New Zealand Society of Animal Production 75, 6466.
Sun, XZ, Waghorn, GC, Hoskin, SO, Harrison, SJ, Muetzel, S and Pacheco, D 2012a. Methane emissions from sheep fed fresh brassicas (Brassica spp.) compared to perennial ryegrass (Lolium perenne). Animal Feed Science and Technology 176, 107116.
Tavendale, MH, Meagher, LP, Pacheco, D, Walker, N, Attwood, GT and Sivakumaran, S 2005. Methane production from in vitro rumen incubations with Lotus pedunculatus and Medicago sativa, and effects of extractable condensed tannin fractions on methanogenesis. Animal Feed Science and Technology 123–124 (pt 1), 403419.
Van Kessel, JAS and Russell, JB 1996. The effect of pH on ruminal methanogenesis. FEMS Microbiology Ecology 20, 205210.
Weatherburn, MW 1967. Phenol-hypochlorite reaction for determination of ammonia. Analytical chemistry 39, 971974.
Williams, SRO, Moate, PJ, Deighton, MH, Hannah, MC, Wales, WJ and Jacobs, JL 2016. Milk production and composition, and methane emissions from dairy cows fed lucerne hay with forage brassica or chicory. Animal Production Science 56, 304311.


Effect of altering ruminal pH by dietary buffer supplementation on methane emissions from sheep fed forage rape

  • X. Z. Sun (a1) (a2), R. Harland (a2) and D. Pacheco (a2)


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