Why Does Perinatal Lamb Mortality Increase in Norway? (194854)

There has been a substantial increase in lamb mortality in Norway. According to the Sheep Recording System (SRS), stillbirths have increased by 27 % since 2000 (to 4.2 % of lambs born) and lambs dying shortly after birth by 15 % (to 3.2 %). Annual economi c loss due to lamb mortality is estimated to NOK 125 million. Moreover, neonatal diseases and deaths are serious animal welfare problems. The causes of the increase are unknown. Various explanations have been suggested: changes in management practices, in creased occurrence of infectious diseases, insufficient placenta function in late pregnancy (particularly in ewes with multiple lambs), birth difficulties, genetic factors, or a combination of these factors. This research project addresses all these poten tial causes. Collaboration has been established between NVH, UMB and the industry, including expertise in pathology, microbiology, genetics, perinatal clinical pathology and epidemiology. A comprehensive field study will be carried out. Flock characterist ics will be recorded, ewes will be monitored during pregnancy and lambing, lambs will be studied in the neonatal period, and dead lambs will be autopsied. Blood samples will be collected for clinical chemistry and haematology. Possible infectious causes w ill be elucidated by appropriate methods. Tissue and blood samples from dead lambs and their siblings, mother and sire will be used for genetic analyses. The diagnostic procedures will reveal ultimate causes of death. Factors affecting the risk of death w ill be identified by analysis of flock and ewe data. A separate epidemiological study will be based on data in the SRS registry, which includes annual records for 280,000 ewes. Available data allow analyses of risk factors for both stillbirth and neonatal mortality. Based on new knowledge of causes and risk factors, preventive measures will be implemented in the flocks. Results may also be important when future sheep breeding strategy is considered.