Funding for this research was provided by:
Bundesanstalt für Landwirtschaft und Ernährung (2810HS005)
Received: 1 June 2019
Accepted: 25 November 2019
First Online: 5 December 2019
Ethics approval and consent to participate
: The participation in the study was voluntary. Farmers gave their written consent to participation. All procedures involving animals were carried out in compliance with the Animal Welfare Act (09.12.2010) of Germany and were declared at the State Office for Consumer Protection and Food Safety of Lower Saxony (LAVES: reference No. 13A308), the Ministry for Energy Turnaround, Agriculture, Environment, and Rural Areas of the State Schleswig-Holstein (MELUR: reference No. V 312–7224.123-34) and the State Office for Nature, Environment and Consumer Protection of Northrhine-Westfalia.
: Not applicable.
: The authors declare that they have no competing interests.