Dr. Murai Éva szerk.: Parasitologia Hungarica 22. (Budapest, 1989)
rise phenomenon that is associated with sheep. Pasture rotation was practiced at Shoe Cove probably resulting in the low prevalence (27-32%) and egg counts noted there. (ív) Egg types The most prevalent egg group was Ostertagia Trlchostrongylus Cooperia (OTC: 60% of positive animals), and was most common in February-May. Haemonchus Oesophagostomum (HO) had a prevalence of 30% with peaks in April-May and August-September. Bunostomurn and flukes (Fasclola , Dlcrocoelium , Paramphistomum) occurred in lesser numbers (5% and 5% prevalence respectively). The former was found in May-January, while the latter were commonest in January-May. Only one animal was infected with Trichuris. Data from the present study are similar to those recorded in Ontario (16). Among cattle on the community pastures the most commonly occurring eggs were those of the OTC group (56%) followed by HO (22%), Bunostomum (16%) and Nematodirus , Trichuris , and trematodes (2% each respectively). The presence of Nematodirus on the pastures used by heifers is in agreement with the reports of other workers (Marltimes (17); Ontario (16); Quebec (8)). A comparison of the dairy cattle on farms with the community pasture stock shows that gastrointestinal helminths were present at subclinical levels In both groups but the prevalence was highest In the former group. Pastured animals had fewer strongylid egg groups (OTC, HO) and trematodes, but more were infected with Bunostomum, Nematodirus , and Trichuris . SUMMARY The majority of positive cattle feces (97%) contained In the range of 0.1 to 5.0 epg. Only 2% of positive infections were in the range 5.1 to 10.0, to give a combined total of 99% of the infected cows with counts under 10 epg. This is in agreement with the observation that the average epg in United States dairy cattle was less than 10 (9). Approximately 1 % of the positive animals recorded an epg over 10. Several workers (2, 3, 20) suggest that cattle with over 5.0 epg should be treated with anthelmintics, and serious consideration should be given to treating animals with less than 5 epg. Local large animal veterinary practitioners suggest treatment If the epg goes over 12, but testing of cattle is not routine in the St. John's area (Provincial Veterinary Services, personal communication). This study shows that 56% of all animals are Infected with parasites, yet routine testing and anthelmintic administration is not carried out on Individual farms. The only time farm animals are checked is when parasitism is suspected or on request of a farmer. Reduced milk production results from artifically Induced subclinical infections with helminths In cattle (2, 3). Individual daily milk production records showed losses of 2.7 lbs/ day (= 1.23 kg/day) (3) and 2.16 kg/day (2). Naturally infected cattle treated with an anthelminthic at parturition showed a increase in milk production in the range of 500 to 750 lbs (226-339 kg) per lactation, based on a 305-day lactation (20). This has resulted In much discussion on the necessity of deworming adult dairy cattle, as they generally have low fecal egg counts ( < 10 epg), despite a high prevalence (> 80%) and are open to constant reinfection on the pasture (9). Further, adult cattle seem to exhibit an age resistance without ever having been exposed to helminths (10), while previous exposure may result in the development of a strong immunity towards reinfection (13). Thus, while many people do not consider the treatment of adult cattle necessary, others (e.g. 21) feel that a fecal egg count as low as 2 epg can have a great effect on milk production.
