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What data needs were addressed? Estimating gross energy intake for dairy cattle.
Why was the data needed? Hungary’s national feed nutrition standards (Hungarian Nutrition Codex, 2004) are based on the NRC equations that underlie the IPCC model for enteric fermentation. However, there are some differences in the underlying methodology. This means that there are some differences in gross energy estimations made using the IPCC method and the Hungarian feed standards.
Methods used: national energy balance model.
How was the data gap addressed? The main difference between the Hungarian and the IPCC model is that the Hungarian model does not differentiate between net energy for maintenance and activity, but takes both energy requirements into account as net energy for maintenance. Hungary’s inventory compilers decided to estimate these separately using Eq. 10.5 of 2006 IPCC Guidelines. Calculation of net energy for lactation also differs from the IPCC methodology. Inventory compilers applied both equations and found that the Hungarian standards gave higher values than the IPCC model. They decided to calculate net energy for lactation using the Hungarian standards, on the grounds that this is more reliable for common Hungarian breeds. The equations used for net energy for pregnancy were different, but the result of the calculation was very similar, so the simpler IPCC equation was applied. Finally, for converting net energy requirements into gross energy intake, data on diet composition derived from a national Farm Accountancy Data Network (FADN), and digestibility values for the different dietary components were taken from the ‘feed database’ provided in the Hungarian Nutrition Codex (2004). This database contains results of laboratory measurements for feeds in Hungary.
Author: Andreas Wilkes, Values for development Ltd (2019)