THE MEAN, DISTRIBUTION AND REPEATABILITY OF FECAL EGG COUNTS IN POLISH WRZOSOWKA EWES FOLLOWING NATURAL GASTROINTESTINAL NEMATODE INFECTIONDURING 2 PASTURE SEASONS

Faecal egg counts per gram of faeces (EPGs) were measured over a perio d of two years (1995-1996) in Polish Wrzosowka ewes. Measurements were made at monthly intervals. The first examination in each years was co nducted before the start of the grazing season, while the rest of the samples were collected during grazing season. The animals were drenche d in May 1996 but not in 1995. EPG were estimated by modified McMaster method and were transformed by log (EPG+1) prior to analyses. Infecti ve larvae of nematode species were identified according to the method described in Anonymous (1986). Meteorological data were collected to e valuate the influence of rainfall and temperature on the faecal egg co unts. The MINITAB programme was used to calculate the correlation coef ficient between EPGs in different sampling. There was substantial vari ation among individuals in their EPG. Several nematode species were pr esent; however two nematode genera were dominant: Haemonchus contortus and Trichostrongylus sp. The mean count and the composition of the ne matode population was influenced by the weather conditions. H. contort us was the main egg producer during the period of high mean counts whe n the temperature and rainfall were highest. The correlations between EPG on successive sampling were positive and nearly always significant .