Nitrogen Balance on Small Dairy Farms in Central Bosnia Region

Abstract

Due to negative ecological aspects of livestock nutrition/production, in many countries worldwide farmers are encouraged to quantify and adjust nutrient balance (particularly nitrogen and phosphorus) on their farms. Differences between managed inputs and outputs is a good indicator of environmental sustainability of livestock production. Ideally, N balance on the farm should be close to zero; however, in practice, due to gaseous losses, nitrate leaching and soil stock changes, this target cannot be achieved. The investigations were conducted on five small dairy farms in the central Bosnia region. The average number of animals per farm was 13.2, ranging from 8 to 23. Average milk production was 82060 kg/year. All of the farms grew feed (mainly forage) on the farms that were fed to their cows. Average land size for animal feed production was 10.66 ha. The farmers bought almost all of the concentrates on the market and imported to the farm. All inputs (animals, feed, fertilizers) and outputs (milk, animals, manure) were used to calculate the balance. The major inputs in the farms were feed while milk was the main output accounting for 78.30% of all inputs and 77.99% of all outputs, respectively. Whole farm nitrogen balance ranged from 2.31 to 6.51. The main reason for considerably high whole farm nitrogen balance is low nitrogen utilization efficiency caused, apart from variability in protein digestibility, by unbalanced ration for animals. Thus, the best way to reduce the whole farm nitrogen balance is to maximize conversion of nitrogen from feed to milk using balanced rations as well as feeds with better nitrogen (protein) digestibility