Presence of antibodies against Ostertagia ostertagi in bulk tank milk from cattle herds in the northeastern Baltic countries of Europe

Ostertagia (O.) ostertagi is a common cattle parasite that can be found on all cattle farms where animals have access to pastures. To evaluate the presence of anti-O. ostertagi antibodies in cattle herds, bulk tank milk (BTM) samples were evaluated using a commercial ELISA test (SVANOVIR (R) O. ostertagi Ab ELISA, Svanova, Sweden). Samples (n=830) were collected from dairy cattle herds in Estonia, Latvia, Lithuania, and Poland. The average BTM optical density ratio (ODR) values in Poland and Estonia were 0.400 and 0.493, respectively. Higher BTM ODRs were obtained in samples collected in Lithuania (0.695) and in Latvia (0.703), which may correlate with the reduction in milk yield by 0.75-1.2 kg of milk per cow per day in Lithuania and Latvia. The first investigations on ostertagiosis using BTM samples were conducted in Poland in 2011. To our knowledge, this is the first report to use BTM ELISA ODRs to evaluate ostertagiosis in cattle in Estonia, Latvia, and Lithuania.