EN
The aim of the paper was to estimate the course of mallophagan invasion in foals from stable mares as well as from forest-bred ones staying together in the stable. Estimation of the course of mallophagan invasion was conducted from November 2006 to May 2007 in foals from stable mares as well as from forest breeding mares. The extensiveness of W. equi invasion in young mares from stable breeding increased from 83.3% in January to 100% in April and May. In young stallions from this group in the first months of investigations it was 25% and kept increasing since February reaching 75% in the last months of alcove breeding. Young forest-bred horses were free from mallophagans on the day of taking them into the stable. After a one-month stay in the stable they became infected. In young mares from forest breeding the extensiveness of invasion increased from 25% in February to about 87% in March. In April and May it reached 100%. A similar increase in the extensiveness of invasion was observed in stallions. The total number of mallophagans and their eggs in 100 mg of coat in mares from the stable group was 21 in January and 34 in April. Considerably smaller number of parasites was found in the coat of mares caught in the forest. The intensity of W. equi invasion in young stable-bred stallions was almost the same as in the forest-bred ones. It was found that young mares from both groups of horses are more susceptible to mallophagan invasions than stallions, and the forest-bred foals are more resistant to W. equi than those that grew up in the stable.