Dr. Murai Éva szerk.: Parasitologia Hungarica 22. (Budapest, 1989)
mont {3 epg) more closely approximate those in the present study (20). Differences such as those noted may be explained by the Influence that rainfall and yearly temperature have on rate of infection (14). Newfoundland has a climate that tends to being cold and wet, or hot and dry. These conditions are not conducive to larval development or survival. As with the dairy cattle the majority of fecal samples from community positive cattle contained less than 5 epg (258 samples, 0 epg; 150, 0.1-5.0 epg; 9, 5.1-10.0 epg; 1, 10.1-15.0 epg; 2, 15.1-20.0 epg). (ili) Parasites and farm management practices Despite the light infections significant differences were noted in Infections between farms (X 2 = 699, df= 99, P<'0.01), probably as a result of farm location and/or management practices. Farm practices were similar in five cases that showed similar epg counts. On the other five farms a single obvious variable was noted that may have resulted in a lower (4 farms) or higher (1 farm) epg count. Two farms administered anthelmintics at calving and had a significantly lower number of epg than another nearby farm with similar management practices (P< 0.01). The farm with the heaviest infections was the one that pastured Its cattle earliest, in late May, with the majority of farmers in the sample area pasturing their cattle 3-4 weeks later. The 3-4 week time interval may be critical in acquisition of. larvae, and subsequently adult worms. Overwintering larvae die if they fall to find a host within a short time of temperature increases that are normally associated with spring (19). The early group of cattle may have grazed on more heavily contaminated pastures than later releases. Indeed on a farm where the cattle were not pastured until early July the epg approximated that of the two farms where the cattle were treated with anthelmintics. Manure provides larvae and eggs with an ideal location to overwinter (11). Management of manure is Important in control of parasitic infections. In Newfoundland manure is generalIv stockpiled over winter and then spread in spring. On one farm manure was spread yearround, resulting in a 2.5-5.0 cm layer all over the field that was subject to cold and wetness from all sides. In winter the manure would be spread on frozen, snow-covered ground subjecting it to complete rapid freezing. This layer would provide little protection for larvae and eggs and result in few Infective forms, as reflected In the egg counts for the farm (as low as those on the treated farms). A third method of manure management, which appeared to enhance contamination, was utilized on a farm that had one of the highest egg counts. Manure was placed In small piles (about 1.8 m diameter x 0.75-1.25 m high) throughout the pastures. Larvae overwintered In these piles and then migrated (15) onto the nearby grass in spring resulting in heavy contamination. The majority of trematode eggs were noted in cows from farm 10 that had considerable patches of marshland associated with the pasture, and which would provide an Ideal habitat for the snail intermediate host. The community pastures exhibited different management practices that could have influenced the worm burdens. The pasture at Aquaforte was used for both cattle and sheep. Crosstransmission of gastrointestinal parasites between cattle and sheep is a common occurrence for genera such as Cooperia and Trichuris but not for Nematodlrus or Ostertagia (18). The majority of the Trichuris occurred in animals from the Aquaforte pasture, infection probably resulting from cross-transmission. The practice of mixing sheep and cattle on the same pasture may lead to an Increase in the worm burden of the cattle, especially with the spring
