Effects of psoroptes ovis infection and its control with an ivermectin controlled-release capsule on growing sheep. 1. Evaluation of weight gain, feed consumption and carcass value.
To evaluate the prophylactic and therapeutic effects of an ivermectin controlled-release capsule (IVM-CRC) on the productivity of growing sheep infested with Psoroptes ovis 24 male and 24 female Merino landrace lambs, 5-6 months old and weighing 21.2-35.0 kg, were used. Sixteen replicates of three animals were formed based on sex and Day 0 body weight. Within each replicate animals were randomly allocated to one of three groups: untreated control; IVM-CRC on Day 0; IVM-CRC on Day 84. For treatment an IVM-CRC for sheep weighing 20-45 kg was used which is designed to deliver ivermectin at a minimum dose of 20 microg/kg per day for 100 days. The lambs were infested with 50-60 P. ovis mites each on Days 14 and 21. Mites in skin scrapings were counted on Days 70, 84, 98, 112 and 126. Body weight and feed consumption were measured every 2 weeks from Day 0 to 126. The animals were slaughtered on Day 127 and their carcasses evaluated. The IVM-CRC treatment on Day 0 prevented the establishment of P. ovis. All untreated lambs became infested. The lambs treated with an IVM-CRC on Day 84 became mite-free from Day 112 onwards. The lambs treated on Day 0 had significantly (p<0.05) greater body weight gain from Day 0 to 84 (13.9 kg) and Day 0 to 126 (20.9 kg) than the untreated controls (9.6 and 12.8 kg, respectively) and the sheep treated on Day 84 (8.4 and 14.9 kg, respectively). Feed consumption (Days 0-126) for sheep treated with the IVM-CRC on Day 0 was higher than for sheep treated on Day 84 (p<0.05) and for the untreated controls (p<0.1). The carcasses of sheep treated with the IVM-CRC on Day 0 had significantly (p<0.05) higher warm and cold weights, carcass yield, rib eye area and back fat thickness than the untreated control group and the sheep treated with the IVM-CRC on Day 84. The sheep treated with the ivermectin CRC on either Day 0 or 84 had significantly (p<0.05) better muscle scores and lower muscle pH 1h post-slaughter than the untreated controls. There was no significant (p>0.1) difference between warm and cold carcass weights, carcass yield and rib eye area between sheep treated on Day 84 and untreated controls.
Rehbein
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Merial GmbH, Kathrinenhof Research Center, Walchenseestr. 8-12, D-83101, Rohrdorf, Germany. steffen.rehbein@merial.com
Barth
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Visser
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Winter
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Cramer
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Langholff
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WK
D000818:Animals; D001835:Body Weight; D003692:Delayed-Action Preparations; D002149:Energy Intake; D005260:Female; D007306:Insecticides / Q000008:administration & dosage / Q000627:therapeutic use*; D007559:Ivermectin / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008460:Meat / Q000592:standards*; D012532:Scabies / Q000503:physiopathology / Q000517:prevention & control / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000503:physiopathology / Q000517:prevention & control*; D015430:Weight Gain
D003692:Delayed-Action Preparations; D007306:Insecticides; D007559:Ivermectin