Excretion calculation of horses in Finland

The official excretion calculations provide the Finnish national annual amounts of dry matter, organic matter and nutrients excreted by different livestock in faeces and urine. Natural Resources Institute Finland (Luke) is responsible for the national excretion calculations in Finland, and the results are used e.g. in estimating emissions during manure management and use into air (greenhouse gases, ammonia) and waters [phosphorus (P), nitrogen (N), potassium (K)], in estimating the quantity and composition of manure produced in Finland and in setting the targets to improve its utilization (nutrient balances, circular economy). The amounts of nutrients excreted are calculated as the difference between nutrient intake in feed and the nutrients retained in the animals and their products, i.e. as "nutrient input – nutrient uptake = nutrient excretion" The components included in the calculations are N, P, K, dry matter and organic matter. The excretion calculations of horses are conducted separately for different animal categories based on the horse’s size and activity. The critical factor of nutrient excretion calculations is to accurately estimate the amounts and nutrient concentrations of feeds consumed by the animals. This was obtained by calculating the energy requirement of the animals based on their maintenance requirements and level of activity. The diet composition was based on field data and expert assessments. The highest uncertainty is in estimating the intake of nutrients. The detailed steps of the calculations are described in the report. Based on the results with year 2023 as an example, the annual N, P and K excretion of one adult horse working on moderate intensity activity level were 46.3, 8.0 and 47.7 kg, respectively. For ponies and small horses working on the corresponding activity level, the annual N, P and K excretions were 30.2; 5.1 and 30.4 kg, and for small ponies 20.2; 3.3 and 19.5 kg, respectively.