The net contribution of dairy production to human food supply: The case of Austrian dairy farms

Due to their ability to convert human-inedible fibrous plant materials into high quality animal products, ruminants have always played an important role as net food producers. However, to meet the animals' nutritional requirements, today's rations for high yielding dairy cows also contain substantial amounts of potentially human-edible feeds (e.g. cereals and pulses), which increases competition between animal feed and human food availability. The aim of the present study was therefore to calculate the human-edible feed conversion efficiency (heFCE) for 30 Austrian dairy farms operating under different production systems in order to evaluate their contribution to net food production. The heFCE was calculated at farm gate level on a gross energy and crude protein basis, and was defined as potentially human-edible output in the form of animal products (milk and meat) divided by the input of potentially human-edible feedstuffs. The potentially human-edible fraction of all feedstuffs used on the 30 farms was estimated based on available literature using a “low,” “medium,” and “high” scenario, representing low, average, and above average extraction rates of human-edible nutrients from feedstuffs, respectively. The human-edible fraction ranged from 0% for some fibrous feedstuffs up to 100% for some cereals in the high scenario. For the “medium” scenario, heFCE ranged from 0.50 up to 2.95 for energy and from 0.47 up to 2.15 for protein. About half of the analysed farms showed a heFCE below 1, indicating a net loss in food supply. For both energy and protein, heFCE was negatively correlated with the amount of concentrates per kg milk and the total amount of concentrates per cow and year. In addition, we found a positive correlation between heFCE and the area of grassland utilized per ton of milk, as well as a negative correlation between heFCE and the area of arable land required per ton of milk. Therefore, feeding large amounts of concentrates to dairy cows has to be questioned in terms of the heFCE. The results of this study clearly show that grass-based dairy production highly contributes to net food production, particularly if the amount of concentrates per kg milk is reduced.