Abstract #484

# 484
Antibiotic use in cubicle housing and freewalk barn systems.
A. Kuipers*1, P. Galama1, H. Wemmenhove1, 1Wageningen University and Research, Wageningen, Gelderland, the Netherlands.

Antibiotics use in animals has become part of societal discussion. Therefore, this topic was included in the www.freewalk.eu project studying the use in different housing systems. Antibiotic use was examined in an earlier stage on 94 cubicle housing farms (no ecological) during 2005–2012 (JDS 99:1632–1648). Level of use (in no. of daily dosages-ADDD) was rising in period 2005–2007, followed by a period of growing societal interest in animal antibiotic use resulting in a reduction in use from 2010/11 on. On average, 68% was applied to the udder: mastitis 25% and dry-cow therapy 43%; other drugs tended to decrease the most, while farmers were reluctant to lower use of dry-cow therapy tubes. Use of sensitive drugs (also human used) minimized from 18% of ADDD in period 2005–2010 to 1% in 2012. The data have been recently updated to 2017. ADDD dropped in this period on average from 6.41 in 2007 (top year in use) to 3.12 in 2017 (50% reduction). Antibiotic use and treatment classes on these farms are compared with 24 freewalk (bedded pack) barn systems and 10 ecological farms, which function in this study as indicator for a minimum use level, including a few artificial floor housing systems. In total about 45 freewalk systems are operating in the Netherlands, of which 10–15 with ecological farming and/or human care agriculture. The freewalk and cubicle farm groups had in period 2012 to 2017 comparable average herd sizes (95 to 125 cows), although the freewalk farms were slightly faster growing. In this period, the group of freewalk farms used significantly less antibiotics than the cubicle farms. Presently the historic use of the freewalk farms in period 2005 to 2011 is assessed to better explain the noted difference in use. These farms changed from cubicles to the freewalk system around 2012 or later. Besides housing system, also farm, farmer and herd indicators are studied over 2005 to 2017 to help explaining the difference in use. Research on part of this data indicates significant correlations between calving interval, cell count and overall use of antibiotics and dry cow therapy tubes. The role of the farmer will be addressed as well.

Key Words: antibiotic use, housing system, herd factors