Quantifying production losses associated with foot and mouth disease outbreaks on large-scale dairy farms in Rift valley, Kenya.

Foot and Mouth Disease (FMD) is a contagious viral disease to which dairy cattle are highly susceptible. An outbreak of FMD in a dairy herds can cause a drop in milk yield, increase mastitis infections, and force culling. These production losses can be substantial, but farmers undervalue the magnitude of the loss that they incur. The study quantified the association of FMD outbreaks with milk yield, mastitis incidences, and culling rates. The data was from three large-scale dairy farms with a recent history (2008 to 2018) of FMD outbreaks in a region endemic for the prevalence of serotype C of the FMD virus since the mid-1980s in the Rift valley of Kenya. A total of 507 cows were monitored for three consecutive periods of six weeks before, during, and after FMD outbreaks. Relative to the period before and after the disease outbreak, production losses were marked during the outbreak. A disease outbreak was associated with up to 4.7% of the cows drying off (n = 24) and milk production dropped by 16.1%. The incidence of mastitis increased from 5.4% to 21.5% (OR = 3.31, CI = 2.27, 4.83) and culling rates increased from 0.59% to 3.8% (OR = 6.71, CI = 1.99, 22.58).