A cohort study of the effect of winter dysentery on herd-level milk production

摘要: Winter dysentery (WD) is a contagious disease caused by bovine coronavirus. It characterized acute onset of diarrhea, fever, depression, and reduced milk yield in adult cattle. Although production loss well-known consequence WD, large-scale studies estimating the effect on are lacking. The objective this study was to estimate farmer-reported WD herd-level composition. A cohort performed based reports herd outbreaks winter during regional epidemic Norway 2011-2012. Reports were made farmers, diagnosis outbreak diarrhea adults. Milk shipment data retrieved from dairy company, information size milking system Norwegian Dairy Herd Recording System. We compared herds with reported (n = 224) all same area without 2,093) period. outcome variable analysis volume per cow day, main predictor whether had or not. assessed fitting linear mixed model, adjusting for before outbreak. Similarly, we composition using regression, levels components This estimated total 51 L/cow period, 7 d 19 after lowest 2 reported, when average 19.4 23.0 day days notification (i.e., difference 3.6 L/cow, 15%). gradually declined time. modest, but an increase 11% free fatty acids small fat/protein ratio indicated that might put cows into negative energy balance. Descriptive still 4 mo showed causes considerable decreases production, it alters These findings highlight important consequences should motivate actions prevent between-herd spread