title: Grape marc reduces methane emissions when fed to dairy cows.
abstract: Grape marc (the skins, seeds, stalk, and stems remaining after grapes have been pressed to make wine) is currently a by-product used as a feed supplement by the dairy and beef industries. Grape marc contains condensed tannins and has high concentrations of crude fat; both these substances can reduce enteric methane (CH4) production when fed to ruminants. This experiment examined the effects of dietary supplementation with either dried, pelleted grape marc or ensiled grape marc on yield and composition of milk, enteric CH4 emissions, and ruminal microbiota in dairy cows. Thirty-two Holstein dairy cows in late lactation were offered 1 of 3 diets: a control (CON) diet; a diet containing dried, pelleted grape marc (DGM); and a diet containing ensiled grape marc (EGM). The diet offered to cows in the CON group contained 14.0kg of alfalfa hay dry matter (DM)/d and 4.3kg of concentrate mix DM/d. Diets offered to cows in the DGM and EGM groups contained 9.0kg of alfalfa hay DM/d, 4.3kg of concentrate mix DM/d, and 5.0kg of dried or ensiled grape marc DM/d, respectively. These diets were offered individually to cows for 18d. Individual cow feed intake and milk yield were measured daily and milk composition measured on 4d/wk. Individual cow CH4 emissions were measured by the SF6 tracer technique on 2d at the end of the experiment. Ruminal bacterial, archaeal, fungal, and protozoan communities were quantified on the last day of the experiment. Cows offered the CON, DGM, and EGM diets, ate 95, 98, and 96%, respectively, of the DM offered. The mean milk yield of cows fed the EGM diet was 12.8kg/cow per day and was less than that of cows fed either the CON diet (14.6kg/cow per day) or the DGM diet (15.4kg/cow per day). Feeding DGM and EGM diets was associated with decreased milk fat yields, lower concentrations of saturated fatty acids, and enhanced concentrations of mono- and polyunsaturated fatty acids, in particular cis-9,trans-11 linoleic acid. The mean CH4 emissions were 470, 375, and 389g of CH4/cow per day for cows fed the CON, DGM, and EGM diets, respectively. Methane yields were 26.1, 20.2, and 21.5g of CH4/kg of DMI for cows fed the CON, DGM, and EGM diets, respectively. The ruminal bacterial and archaeal communities were altered by dietary supplementation with grape marc, but ruminal fungal and protozoan communities were not. Decreases of approximately 20% in CH4 emissions and CH4 yield indicate that feeding DGM and EGM could play a role in CH4 abatement.
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Ellinbank, Victoria 3821, Australia. Electronic address: peter.moate@depi.vic.gov.au.
authors: P J
authors: PJ
authors: Moate
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Ellinbank, Victoria 3821, Australia.
authors: S R O
authors: SR
authors: Williams
authors: South Australian Research and Development Institute, Soil Biology and Diagnostics, Waite Campus, Urrbrae, South Australia, 5064, Australia.
authors: V A
authors: VA
authors: Torok
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Ellinbank, Victoria 3821, Australia.
authors: M C
authors: MC
authors: Hannah
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Ellinbank, Victoria 3821, Australia.
authors: B E
authors: BE
authors: Ribaux
authors: AgResearch, Palmerston North 4442, New Zealand.
authors: M H
authors: MH
authors: Tavendale
authors: Melbourne School of Land and Environment, The University of Melbourne, Victoria 3010, Australia.
authors: R J
authors: RJ
authors: Eckard
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Warrnambool, Victoria 3280, Australia.
authors: J L
authors: JL
authors: Jacobs
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Ellinbank, Victoria 3821, Australia.
authors: M J
authors: MJ
authors: Auldist
authors: Future Farming Systems Research Division, Department of Environment and Primary Industries, Ellinbank, Victoria 3821, Australia.
authors: W J
authors: WJ
authors: Wales
mesh_terms: D000818:Animals; D002417:Cattle; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D005285:Fermentation; D007774:Lactation; D019787:Linoleic Acid / Q000032:analysis; D008697:Methane / Q000096:biosynthesis*; D064307:Microbiota; D008892:Milk / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D019787:Linoleic Acid; D008697:Methane
keywords: fat; fatty acid; microbial profiling; tannin