Management of gastrointestinal nematode parasites on sheep farms in New Zealand.
OBJECTIVE
To report current farmer opinions and farming practices relating to control of gastrointestinal nematodes and anthelmintic resistance on sheep farms in New Zealand.


METHODS
An interview-based cross-sectional study of grazing management and anthelmintic usage was conducted by veterinarians on 80 randomly selected sheep farms in New Zealand.


RESULTS
Useable data were returned by 74/80 (92%) farmers who participated in the study. However, despite contacting 400 farmers the target sample size of 100 farms was not reached. The results indicated that only 31% of farms had previously tested for drench resistance, that effective quarantine-drenching of imported stock was not always carried out, and that farmers were more likely to integrate cattle than ewes into their grazing management of lambs. Furthermore, the number of drenches given to lambs had changed little in 25 years. The use of faecal egg counting by farmers has increased.


CONCLUSIONS
Dependence on anthelmintics continues to be high on sheep farms in New Zealand. Whilst the number of drench treatments has changed little, there is more widespread use of persistent or long-acting treatments. Farmers need to be encouraged to monitor the resistance status of nematode populations on their farms and use this information to develop strategies aimed at maintaining susceptible alleles within the parasite populations and conserving the efficacy of existing drug families.
Lawrence
K E
KE
Institute of Veterinary Animal and Biomedical Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand. k.lawrence@massey.ac.nz
Lethwick
D M
DM
Rhodes
A P
AP
Jackson
R
R
Heuer
C
C
Pomroy
W E
WE
West
D M
DM
Waghorn
T S
TS
Moffat
J R
JR
D000822:Animal Husbandry; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D004351:Drug Resistance; D005243:Feces / Q000469:parasitology; D005260:Female; D007411:Intestinal Diseases, Parasitic / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D009348:Nematoda / Q000187:drug effects / Q000302:isolation & purification; D009349:Nematode Infections / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D009520:New Zealand / Q000453:epidemiology; D010270:Parasite Egg Count / Q000662:veterinary; D021261:Parasitic Sensitivity Tests / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology / Q000469:parasitology / Q000517:prevention & control*; D011795:Surveys and Questionnaires
D000969:Antinematodal Agents