[Risk factors of increased abortions in dairy herds - a statistical analysis]

To examine whether dairy herds with and without abortion problems differ in their management and prevalence of antibodies against various pathogens, through collecting and analysing data from these herds.

Data on management parameters, clinical examinations and serological results were obtained from 48 dairy herds in middle Hessen. Information on the extent of stock renewal, form of animal housing, type of herd occupancy and use of a maternity pen was compiled. A random sample was taken from every herd, consisting of a minimum of three healthy non-lactating cows, three clinically sound puerperal animals, three animals having had an abortion and three clinically healthy pregnant heifers. In these animals, the body condition score was evaluated and a clinical gynaecological examination was performed. Additionally, these animals were serologically examined for the presence of antibodies against the bovine viral diarrhoea virus, Coxiella, Listeria and Neosporacaninum. A comparison between the herds with and without an abortion problem was performed.

Data of 591 animals from 48 farms was compiled. Thirty-eight herds had an abortion problem. In the affected farms, a maternity pen was used significantly more often and cattle were significantly more frequently housed in free stalls when compared to farms without an abortion problem (p < 0.05). The number of animals serologically positive for Coxiella was significantly higher in herds with abortion problems (p = 0.03). No significant difference was found between the occurrence of antibodies against Listeria and Neospora caninum in herds with or without abortion problems, respectively (p > 0.05).

It was identified that in addition to infectious agents, management/husbandry factors that promote the spread of disease are a risk factor for abortion in dairy cattle. Besides taking steps against pathogens, farms with abortion problems have to implement measures to minimize the spread of infection between animals. A critical control point is likely to be the maternity pen.