title: Enteric methane production, rumen volatile fatty acid concentrations, and milk fatty acid composition in lactating Holstein-Friesian cows fed grass silage- or corn silage-based diets.
abstract: The objective of this study was to determine the effects of replacing grass silage (GS) with corn silage (CS) in dairy cow diets on enteric methane (CH4) production, rumen volatile fatty acid concentrations, and milk fatty acid (FA) composition. A completely randomized block design experiment was conducted with 32 multiparous lactating Holstein-Friesian cows. Four dietary treatments were used, all having a roughage-to-concentrate ratio of 80:20 based on dry matter (DM). The roughage consisted of either 100% GS, 67% GS and 33% CS, 33% GS and 67% CS, or 100% CS (all DM basis). Feed intake was restricted (95% of ad libitum DM intake) to avoid confounding effects of DM intake on CH4 production. Nutrient intake, apparent digestibility, milk production and composition, nitrogen (N) and energy balance, and CH4 production were measured during a 5-d period in climate respiration chambers after adaptation to the diet for 12 d. Increasing CS proportion linearly decreased neutral detergent fiber and crude protein intake and linearly increased starch intake. Milk production and milk fat content (on average 23.4 kg/d and 4.68%, respectively) were not affected by increasing CS inclusion, whereas milk protein content increased quadratically. Rumen variables were unaffected by increasing CS inclusion, except the molar proportion of butyrate, which increased linearly. Methane production (expressed as grams per day, grams per kilogram of fat- and protein-corrected milk, and as a percent of gross energy intake) decreased quadratically with increasing CS inclusion, and decreased linearly when expressed as grams of CH4 per kilogram of DM intake. In comparison with 100% GS, CH4 production was 11 and 8% reduced for the 100% CS diet when expressed per unit of DM intake and per unit fat- and protein-corrected milk, respectively. Nitrogen efficiency increased linearly with increased inclusion of CS. The concentration of trans C18:1 FA, C18:1 cis-12, and total CLA increased quadratically, and iso C16:0, C18:1 cis-13, and C18:2n-6 increased linearly, whereas the concentration of C15:0, iso C15:0, C17:0, and C18:3n-3 decreased linearly with increasing inclusion of CS. No differences were found in short- and medium-straight, even-chain FA concentrations, with the exception of C4:0 which increased linearly with increased inclusion of CS. Replacing GS with CS in a common forage-based diet for dairy cattle offers an effective strategy to decrease enteric CH4 production without negatively affecting dairy cow performance, although a critical level of starch in the diet seems to be needed.
authors.affiliation: Top Institute Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands. Electronic address: sanne.derksen-vangastelen@wur.nl.
authors.forename: S
authors.initials: S
authors.lastname: van Gastelen
authors.affiliation: Top Institute Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Food Quality Design Group, Wageningen University, PO Box 17, 6700 AH Wageningen, the Netherlands.
authors.forename: E C
authors.initials: EC
authors.lastname: Antunes-Fernandes
authors.affiliation: Food Quality Design Group, Wageningen University, PO Box 17, 6700 AH Wageningen, the Netherlands.
authors.forename: K A
authors.initials: KA
authors.lastname: Hettinga
authors.affiliation: Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Klop
authors.affiliation: Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: S J J
authors.initials: SJ
authors.lastname: Alferink
authors.affiliation: Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: W H
authors.initials: WH
authors.lastname: Hendriks
authors.affiliation: Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Dijkstra
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary*; D004043:Dietary Fiber / Q000378:metabolism; D004063:Digestion; D005227:Fatty Acids / Q000032:analysis*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000378:metabolism; D007774:Lactation; D008697:Methane / Q000096:biosynthesis*; D008892:Milk / Q000737:chemistry*; D009584:Nitrogen / Q000378:metabolism; D006109:Poaceae / Q000378:metabolism; D012417:Rumen / Q000737:chemistry*; D012820:Silage; D013213:Starch / Q000378:metabolism; D003313:Zea mays
chemical_list: D004043:Dietary Fiber; D005227:Fatty Acids; D005232:Fatty Acids, Volatile; D013213:Starch; D009584:Nitrogen; D008697:Methane
keywords: corn silage; dairy cow; enteric methane production; grass silage