Pregnancy loss due to abortion is one of the major causes of reduced fertility and contributes to adverse economic effects for dairy farms. After five months of pregnancy, abortion is frequently characterized by retained placenta or a cow failing to expel foetal membranes for a few days after losing the foetus. Depending on the stage of pregnancy, the general causes of abortion include infectious agents like bacteria such as brucellosis, leptospirosis and salmonellosis.
Abortion can also be due to viral agents such as Bovine viral diarrhoea, fungi and mycotoxins, genetic abnormalities, high fever, environmental stresses like excess heat, protozoal parasites, injuries, poisons and toxins from plants.
Feeding mouldy feeds like hay or silage is also a possible cause of mycotoxins. An affected cow may return to heat but does not settle until she recovers from the infections after several heat cycles.
Note that all abortion prevention measures start with herd health and other management programmes. Work closely with your veterinarian to determine the cause and develop a vaccination or management programme to prevent further losses.
Take bio-security measures to minimize the risk of introducing diseases, develop proper feeding strategy and control the use of bulls. The main cause of abortion is determined by sending a freshly aborted foetus to a diagnostic laboratory.