Health assessment in Swiss dairy production with confinement and pasture-based feeding

The majority (88%) of Swiss dairy herds have access to a pasture in summer. An increasing number of farms apply a confinement-based feeding strategy where the pasture is used for animal welfare. In contrast, farms with pasture-based feeding strategy feed whenever possible on pasture. The aim of this study was to compare several health indicators in these two dairy systems throughout the year. Each 15 farms of the two systemes were visited once during spring, summer and autumn to assess the prevalence of hairless patches, injuries, swellings and lameness using a standardized protocol. Compared to the pasture-based system, the confinement-based system had (median and range) more hairless patches 15.2% (2.9-60.0%) vs. 4.2% (0-41.0%), injuries 4.5% (0-36.7%) vs. 0% (0-4.3%), swellings 6.5% (0-30%) vs. 0% (0-4.2%) and lame cows 11.4% (0-40%) vs. 0% (0-9.5%). Confinement-based herds consisted mainly of dairy breeds and 80% of the pasture-based herds of dual-purpose breeds. Average milk yield (±SD) was 9800 (±881) kg/cow/year in confinement-based systems and 5920 (±910) kg/cow/year in pasture-based systems. Several factors can affect health issues. These may be related to the quality of housing systems which differed among farms, but also to factors such as breed and production level. In addition, grazing and regular hoof care influence claw health and therefore the prevalence of lameness. Since all pasture-based herds and 44% of the confinement-based herds are longer than 4 hours/day on pasture and the period with pasture access is on average 7.5 (SD=1.3) months in the confinement-based system and 8.8 (SD=0.7) in the pasture-based system the farm effect might eventually be larger than the system effect for these health issues, further analysis is required to statistically evaluate if the season or system has significant influence on these parameters. Although there is a clear difference in feeding strategy and production level among the two dominant dairy systems in Switzerland animal welfare is influenced by many other factors, and therefore a careful analysis needs to be done before conclusions can be drawn.