Effect of replacing barley grain with oat grain in the diet of dairy cows on methane production in vitro

• Main Author: Fant, Petra
• Other Authors: Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta, Maataloustieteiden laitos, University of Helsinki, Faculty of Agriculture and Forestry, Department of Agricultural Sciences, Helsingfors universitet, Agrikultur- och forstvetenskapliga fakulteten, Institutionen för lantsbruksvetenskaper
• Format: Master Thesis
• Language: English
• Published: Helsingin yliopisto 2017
• Subjects: methane; dairy cattle; oats; in vitro; Kotieläintiede; Animal Science; Husdjursvetenskap; Northern Sweden
• Online Access: http://hdl.handle.net/10138/225303

The aim of this master’s thesis was to investigate the potential of reducing enteric methane production from dairy cows by replacing barley grain with oat grain on a grass silage-based diet. The effects of grain species on in vitro methane production, digestibility, pH and volatile fatty acid (VFA) production pattern were investigated and a regression analysis was performed to entangle possible methane mitigating mechanisms of oats. The study was conducted in the laboratory at the Department of Agricultural Research for Northern Sweden in the autumn of 2016. An in vitro gas production system was applied, consisting of 16 diets with two replicates, four blanks and three runs, each with a three-day incubation time. The feed material consisted of eight varieties of barley, eight varieties of oats and timothy silage incubated at a grain/silage ratio of 1:1 on a dry matter basis. Rumen fluid was collected from two cannulated Nordic Red dairy cows after morning feeding. Gas sampling was performed at 2, 4, 8, 12, 24, 32 and 48 hours of incubation, meanwhile VFA-sampling, pH-measurements and sampling of incubation residues were performed at 48 hours. Methane production was estimated as predicted in vivo methane production and stoichiometrically predicted methane production. The in vitro digestibility was determined as true dry matter digestibility (TDMD). Content of indigestible neutral detergent fiber (iNDF) was determined by applying a 12-day in situ incubation in two Ayrshire dairy cows. Oats had a higher content of crude protein, neutral detergent fiber (NDF), iNDF and fat compared to barley, whereas barley had a higher content of starch. Replacing barley with oats decreased predicted in vivo methane production by 9% and stoichiometrically predicted methane production by 11%. Variety within grain was not found to have any significant effect on methane production. True DM digestibility and total VFA production were lower in oat-based diets compared to barley-based diets. No significant differences were observed ...