Author
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SMITH, LARRY - RES & DEVELOPMENT, INC |
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Gasbarre, Louis |
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Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Proceedings Publication Acceptance Date: 5/2/2005 Publication Date: 7/15/2005 Citation: Smith, L.L., Gasbarre, L.C. 2005. Evaluation of individual or a combinaton of anthelmintics in a commercial cattle population where anthelmintic resistant parasites had been observed the previous year [abstracat]. American Association of Veterinary Parasitologists Proceedings. p. 63. Interpretive Summary: Technical Abstract: More than 4,100 calves weighing 70-100 kg were purchased in the southeastern US during the winter of 2003-2004, and then were placed in either a conditioning yard for 40-60 days prior to pasturing, or were taken directly to pasture. All calves received doramectin when purchased. Calves placed in a conditioning yard were further treated with moxidectin prior to moving to pasture. Calves that went directly to pasture were treated once or twice with either ivermectin plus clorsulon or moxidectin. Approximately 10% of the animals from each pasture were randomly fecal sampled the last week of April for eggs per gram of feces (EPG) determination. At this time, the animals were reassembled, sorted by size and sex, treated with levamisol, and shipped to Wisconsin. In Wisconsin all animals, except for one pasture, were intensively rotationally grazed through the summer and fall of 2004. During the course of the grazing period fecal samples were randomly taken from approximately 10% of the animals on each pasture before each treatment, 14 days after each treatment, and again at the end of the grazing season. On pastures BF, 743 heifers averaging 169 kg at turnout were given 5 mg/kg fenbendazole in the feed for 11 days on June 16-26 and again for 7 days on July 23-29. Egg counts were: 5/20 = 0.5, 6/16 = 20.2, 7/6/04 = 0.5, 7/23 = 1.7, 8/12 = 0.1, 12/22 = 43.9. On pastures HF, approximately 690 steers averaging 162 kg at turnout were given 10mg/kg of fendbendazole in the feed for 8 days on June 16-23, and 5 mg/kg as an oral paste daily for 8 days from July 28 to Aug 4. Egg counts were: 5/20 = 9.1, 6/16= 13.3, 7/7= 19.0, 7/27= 22.9 (range 0-342), 8/18 = 3.6. The owner was dissatisfied with body condition of these animals and animals were retested on 9/9 when a mean EPG value of 62.9 (range 0-564) was observed. All animals were individually treated with 5mg/kg of fendbendazole on 9/10. On 9/23 EPG = 4.3, and samples taken 12/17, just prior to the animals leaving the pasture = 56.1. On JF pastures, 930 steers averaging 193 kg at turnout were treated with eprinomectin and levamisol on 6/17 or 6/18 and again on 8/24. Egg counts were: 5/22 = 5.5, 6/17 = 26.7, 7/2 = 0.04, 8/23 = 26.0, 9/10 = 0.0, and on 12/8 before the animals left the pasture =19.9. On TF pastures, 787 steers averaging 295 kg at turnout were treated on 6/16 and 8/6 with eprinomectin and fenbendazole. Egg counts were: 5/24 = 4.9, 6/16= 21.5, 6/30 = 0.2, 8/5 = 5.5, 8/20 = 0.03, 12/16 = 29.7. On NF pastures approximately 830 heifers averaging 205 kg at turnout were treated with eprinomectin and levamisol on 6/14. Follow-up treatment did not occur until egg counts began to increase. On 10/10 animals were treated with eprinomectin and levamisol. Egg counts were: 5/24 = 8.7, 6/13= 11.4, 6/28 = 0.05, 10/6 = 117.9, 10/26 = 0.1, 11/29 = 5.5. On pasture G (not intensively rotationally grazed), 150 animals averaging 164 kg at turnout were treated on 6/15 and 7/21 with doramectin injectable. Egg counts were: 5/21 =0 .8, 6/15 = 14.8, 6/29 = 4.1, 7/21 = 25.0, 8/4 = 23.6. Because egg counts did not decrease after the third treatment, animals on this pasture were necropsied for parasite recovery and identification. These results will be given in another paper. The results of this study indicate that using a combination of different classes of anthelmintic compounds may be useful in controlling parasite populations in areas where drug-resistant parasites of cattle are prevalent. |
