Keywords: methane conversion factor | modeling | dairy cattle
What data needs were addressed? Prediction of methane yield.
Why was the data needed? To establish a methane conversion factor.
Methods used: Mechanistic model.
How was the data need addressed? The Karoline model is intended to be used by advisory services in Nordic countries including Denmark. The model simulates animal performance (i.e. milk yields) of a given feed in a given situation. The model is a dynamic and mechanistic simulation model for lactating dairy cows, and consists of two ‘sub-models’: one digestion, and one metabolism model. Model inputs include live-weight, week of lactation, rate of dry matter (DM) intake and DM composition. Numerous feed parameters are included as well, including crude protein (CP), crude fat, potentially degradable neutral detergent fibre (NDF), totally indigestible NDF, starch (St), fermentation products and a rest fraction (RF). Model outputs include parameters measuring digestion and nutrient use efficiency (e.g. use of metabolizable energy for lactation), production parameters (milk yield, milk composition, live weight gain), and protein and energy values of the feed ration.
The model can also be applied to quantitative prediction of methane emissions from dairy cows under varying conditions, depending on (i) level feed feeding, (ii) proportion of concentrates in the ration, (iii) digestibility of roughages and (iv) fat, sugar and starch content in the feed. Results from the model are in accordance with experimental data (Ramin & Huhtanen, 2015), hence the model is considered a reliable model for predicting methane emissions from mature dairy cows.
Olesen JE, Jørgensen H, Danfær A, Gyldenkærne S, Mikkelsen MH, Asman WAH, Petersen SO. 2005. Evaluering af mulige tiltag til reduktion af landbrugets metanemissioner. Arbejdsrapport fra Miljøstyrelsen Nr. 11 2005.
Sveinbjrnsson J, Huhtanen P, Udn P. 2006. The Nordic Dairy Cow Model Karoline Development of Volatile Fatty Acid Sub-Model. Nutrient digestion and utilization in farm animals: modeling approaches, 1-14.
Ramin M, Huhtanen P. 2015. Nordic dairy cow model Karoline in predicting methane emissions: 2. Model evaluation. Livestock Science, 178: 81-93.