Natural trichostrongylid exposure of calves in Lithuania: effect of midsummer move to clean pasture with special reference to inhibited development in the early L4 stage trichostrongylid larvae
| Author | Affiliation |
|---|---|
Paulikas, Vygandas | |
Nansen, Peter | Danish Centre for Experimental Parasitology, Institute for Veterinary Microbiology, The Royal Veterinary and Agricultural University, Frederiksberg , Denmark |
| Date |
|---|
1998-06-01 |
The present experiment was designed to examine the effect of transfer to clean pasture in mid-summer on tri- chostrongyle worm burdens in first-season grazing calves in Lithuania. Twenty heifer-calves aged 5—8 months were turned out on a naturally contaminated pasture of 2 ha on 4 June. On 18 July the experimental animals were divided into two comparable groups of 10 calves, balan- ced according to liveweight. Group B was moved to a 2 ha plot that had been used for hay production in the first part of the grazing season. Group A continued to graze on the initial plot. Every two weeks the heifers were weighed and clinically inspected, and faeces, blood and grass samples were collected. The infectivity of the pasture plots was monitored using parasite-naive tracer-calves that were introduced on two occasions, i. e. on 15 August and 3 October, respectively for a 2 week period. Excretion of trichostrongylid eggs and serum pepsinogen levels were higher in group A. Most of the nonmoved calves showed clinical signs of mild parasitic gastroenteritis from the beginning of August and onwards. Results from necropsied tracer-calves showed an increase in pasture infectivity on the plot grazed by group A. This study showed that trichostrongylid infections in cattle in Lithuania may be suppressed by moving animals to safe pasture in the middle of the summer.