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Efficacy of ivermectin in a controlled‐release capsule for the control of breech strike in sheep
Author(s) -
RUGG D.,
THOMPSON D.,
GOGOLEWSKI RP,
ALLERTON GR,
BARRICK RA,
EAGLESON JS
Publication year - 1998
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1998.tb12366.x
Subject(s) - ivermectin , lucilia cuprina , medicine , zoology , veterinary medicine , biology , larva , botany , calliphoridae
Objective To investigate the efficacy of ivermectin in an intraruminal controlled‐release capsule (CRC) against blowfly strike. Design Pen and field trials with controls. Animals Pen studies: Two breech strike trials involving 60 Romney and 60 Merino sheep. One body strike trial using 100 Merino sheep. Field trials: Eight trials in New Zealand used 1000 Romney and Romney‐cross sheep. Fifty Merino lambs in one trial in Australia. Procedure Pen studies: Sheep were allocated to two equal groups. One was not treated, the other sheep received a CRC that delivered ivermectin at 20 μg/kg/day for 100 days. In the breech strike trials, each animal was given an oral laxative 2 days before exposure to adult Lucilia cuprina . In the body‐strike trial, the sheep sheep were kept wet to increase susceptibility prior to the release of blowflies. Field trials: Fifty or 200 sheep allocated to equal groups of nontreated or treated with the CRC and grazed at pasture exposed to natural blowfly challenge. Results Pen studies: Breech strikes developed in 24 of 60 controls but in none of 60 CRC‐treated sheep. There was a 35% reduction in the number of CRC‐treated sheep struck on the body. Field trials: The average number of breech strikes in CRC‐treated sheep was reduced by 86% (P < 0.001). The number of body strikes in the treated groups was a reduced by 27% (P < 0.05). Conclusion The ivermectin CRC is a useful aid in controlling breech strike, but provides only moderate reduction in the incidence of body strike.