Risk factors of cystic ovarian disease in dairy cattle

Abstract

Production and reproduction records of the Holstein dairy herd at Edinburgh University's Langhill farm were analyzed to study the incidence, possible risk factors and to assess the reproductive performance of cows with cystic ovaries. Risk factors investigated were whether a cow was from the genetically selected or control herd, 305 day milk yield equivalent of the previous lactation to the cystic one, and age/parity. For analysis of the consequences of cystic ovarian disease, cystic cows were individually matched to non-cystic herd mates for selection or control herd, age/parity, and month of calving. The cumulative lactational incidence of cystic ovarian disease was 8.1%. Selected herd cows were more at risk of developing cystic ovarian disease than control herd cows (p<0.05) and odds ratio 3.55. There was no significant association between high milk production in the previous lactation and COD (p<0.05). However, a significant association between increasing age/parity and cystic ovarian disease was found (p<0.01). The 305 day milk yield equivalent in the previous and cystic lactation for the cystic cows was not significantly different from the paired herd mates (p>0.05) respectively. However, the cystic cows produced significantly higher 305 day milk yield equivalent in the cystic lactation than the previous non-cystic lactation (p<0.001). The calving to conception and calving intervals were significantly longer in the cystic cows than the non-cystic paired cows (p<0.05) respectively. In conclusion, cystic ovarian disease causes an increase in the calving to conception and calving intervals. COD is common in older cattle. To understand risk factors more research needs to be done, especially high milk production prior to cystic ovarian disease diagnosis in the same lactation.