Novel dairy systems as an adaptation to diminishing phosphate resources
Increasing demand for protein rich diets and a limited supply of arable land creates a food supply issue which imposes further dependence on phosphorus (P). EU food security depends upon imported P and member states should encourage the implementation of closed loop farming systems to increase resource use efficiency, reduce losses to the environment, and lower total P consumption. We assessed the nutrient efficiency of two contrasting genetic merits of Holstein Friesian dairy cows, within UK traditional low concentrate (HF), confined (LF), by-product (BP) and home-grown (HG) dairy feed systems (FS’s) by calculating annual farm gate P nutrient budgets. Farm level budgets were combined with system indicators such as land and nitrogen use to fairly represent each regime. Undesirable output focussed Nonparametric Data Envelopment Analysis (DEA) models were applied to test the comparative eco-efficiency of the dairy FS’s, Both models assess P as an undesirable output, and one also considers its additional role as a non-renewable input. Nutrient budget results show efficiencies ranged from a minimum of 0.29±0.09 within a HG FS to a maximum of 0.49±0.05 within a BP FS exporting all manure. A traditional HF system was more P efficient than a confined LF regime feeding high levels of purchased feeds, at 0.39±0.02 v’s 0.34±0.03. When energy corrected milk (ECM) production was considered, a UK traditional HF FS generated the lowest average surplus P per litre (0.0021±0.0003 kg) whilst the HG FS attracted the highest average surplus of 0.0038±0.002 kg P per litre. Within each FS cows of superior genetic merit always generated lesser surplus P per litre than cows of an average UK merit. Undesirable output orientated DEA model results found a BP system to be most P efficient and average efficiency scores ranged from 0.55 for a superior merit within a HG FS to 0.97 for a superior merit within a BP FS. Highest to lowest system scores were BPS>BPC>HFS>LFS>HFC>LFC>HGC>HGS. Whilst a UK traditional low input system was shown to generate the least amount of surplus P per litre, when further resource use indicators are included DEA results show that a BP system exporting manure to be most efficient which could in part be due to no requirement for land or nitrogen. When combined, a HG and BP FS could theoretically generate a dual production regime in which P is recycled. Manure P exported from the BP system could be utilized within the forages required for a HG system, hence the need for imported fertilizer is diminished and manure P is no longer exported.
Other Titles/Title of Conference
66th European Federation of Animal Science Annual Meeting, Warsaw, Poland
Wageningen Academic Publishers