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Table 1 Calf epg data and recovered worms before and after IVM treatment

From: A controlled study on gastrointestinal nematodes from two Swedish cattle farms showing field evidence of ivermectin resistance

Treatment Calf Origin O. ostertagi C. oncophora epg
    Males Females Males Females  
Before IVM A1 TiHo 2070 3230 6470 5270 750
  B1 Sweden 570 670 9070 13600 1000
  C1 Sweden 900 2900 1930 3070 400
After IVM A2 TiHo 0 0 3330 5730 150
  A3 TiHo 0 0 130 400 <50
  B2 Sweden 0 0 6000 6200 50
  B3 Sweden 100 0 200 200 <50
  C2 Sweden 0 0 600 1600 <50
  C3 Sweden 0 0 1000 2000 <50
  1. Calf epg data from day of slaughter, and estimated numbers of adult worms recovered at necropsy from calves before (31 d.p.i.), and 10 days after (45 d.p.i.) s.c. injection with ivermectin (Ivomec®, Merial). Calves were previously each infected with C. oncophora and O. ostertagi, representing isolates with different deworming history. Calves in group A received equal mixtures of susceptible laboratory maintained C. oncophora and O. ostertagi from TiHo, whereas calves in groups B and C received cattle nematodes from two different farms in Uppland, Sweden, showing phenotypic clinical IVM resistance in previous field trials.