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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.