Tuyển tập các báo cáo nghiên cứu về bệnh học thý y được đăng trên tạp chí Acta Veterinaria Scandinavica cung cấp cho các bạn kiến thức về bệnh thú yđề tài: Risk factors associated with cystic ovarian disease in Norwegian dairy cattle. | Nelson et al. Acta Veterinaria Scandinavica 2010 52 60 http content 52 1 60 AVS ACTAVETERINARIA SCANDINAVICA RESEARCH Open Access Risk factors associated with cystic ovarian disease in Norwegian dairy cattle Sindre T Nelson Adam D Martin Olav 0steras Abstract Background The aims of this study were to establish the incidence of cystic ovarian disease COD and its geographical and seasonal variation in Norway investigate the effect of COD on culling rates and describe the effects of COD on subsequent reproductive performance and its association to twins. Methods Diagnosis of COD was made by veterinary surgeons in the field. Four statistical models were made all including herd as random effect The four different dependent variables investigated were 1 Diagnosis of COD between 40 and 165 days in milk or not n 511 657 2 Twins or singleton data restricted to lactations with new calving n 156 661 3 Culling removal or not n 573 184 4 Culling due to reproductive problems data included only lactations which ended in culling n 234 232 . Model 1 3 and 4 applied Cox regression models and model 2 logistic regression. Independent variables were parity twins singletons calving season herd size region COD occurrence in present lactation if not dependent and COD diagnosis in previous lactation. Results The incidence was per lactation. COD increased with increasing parity was smallest at herd size between 35 and 85 cows. Cows in 1st parity and calved in spring had lowest hazard of COD and hazard for COD diagnosis was highest in autumn with HR - compared to spring. There was an interaction between parity and season. COD incidence was lower south of 60 N. Cows which experienced COD had an increased odds of giving birth to twins OR - . Of those that were culled those with COD were culled more frequently because of reproductive problems HR - for higher parity than 2. Having COD diagnosed in the preceding lactation was a hazard
