Risikofaktoren für eine erhöhte Kälbersterblichkeit und geringe Tageszunahmen von Aufzuchtkälbern in nordostdeutschen Milchkuhhaltungen

- Risk factors associated with calf mortality and growth of calves in dairy farms located in northeastern Germany - Calf health and animal welfare have an impact on lifetime productivity and longevity of dairy cows. Furthermore consumers pay increasing attention to animal health and housing conditions in livestock husbandry today. The occurrence and severity of factor-associated diseases is substantially influenced by management practices. The objectives of this study were to determine management practices in farms in northeastern Germany that can compromise calf health and welfare. Besides, we wanted to identify risk factors that are linked to high calf mortality and poor growth in young dairy replacement heifers. A case-control study was performed in 50 herds, which were selected based on acceptance to participate in the study. Each herd was visited once between 2012 and 2014. A questionnaire on farm management practices, morbidity and calf mortality was completed by in-person interview. Furthermore colostral, blood und fecal samples were collected. Heart girth measurements were conducted to assume average daily weight gain of calves. Additionally a score concerning calf welfare was determined. The epidemiological associations between these factors with calf mortality and with poor growth were estimated by using two regression models including 16 and 25 preselected factors each. The calf mortality ranged between 0.0 and 17.7%. The factors significantly associated with high calf mortality (> 5.0%) were the application of Halofuginone (OR: 10.0) and a high rate of calves with failure of passive transport (OR: 8.1). The access to hay in the first week of life compared to those offered no hay before weaning was linked to a lower calf mortality rate (OR: 0.2). On herd-level the average daily weight gain in calves three month of age was 675 grams per day and ranged between 414 and 1027 grams. The risk factors significantly associated with poor growth were relocating calves more than twice from birth until weaning (-119 g), having an incidence of milk fever under 5% (-115 g), offering hay before weaning (-142 g), collecting first colostrum later than two hours after parturition (-142 g), the amount of concentrates consumed at weaning (+160 g per kilogram concentrates), changing the bedding in the calf pen at least once every two weeks (-96 g), relocating calves more than twice from birth until weaning (-93 g), feeding less than three liters of first colostrum to newborn calves (-88 g) and leaving the farm more than two hours per day unattended (-84 g). These results indicate that management practices like colostrum, feeding and husbandry management have an impact on calf health and animal welfare. Furthermore they give an overview of current management practices in the examined region. With this new knowledge systematic advice can be given to farmers who want to improve calf mortality rates, growth of dairy heifer calves and animal welfare. Further research is required to understand the aetiopathology behind some factors, for example the association between milk fever incidence and growth of calves in dairy farms.