Herd R P, Sams R A, Ashcraft S M
College of Veterinary Medicine, Ohio State University, Columbus 43210, USA.
Int J Parasitol. 1996 Oct;26(10):1087-93.
Sixteen young dairy cows were randomly allocated to 4 groups of 4 animals each: Group 1 cows were each given a single Ivomec SR Bolus; Group 2 cows were treated with the Ivomec Pour-on formulation; Group 3 cows were injected with the Ivomec Subcutaneous Injection; Group 4 cows were untreated controls. Blood and faecal samples were collected from all cows on the day before treatment and on days 1, 2, 3, 7, 14, 21, 28, 35, 42 and 49 after treatment for HPLC determination of plasma and faecal ivermectin concentrations. Group 1 (SR Bolus) cows had mean (+/- S.D.) plasma ivermectin concentrations ranging from 5.6 +/- 1.8 micrograms l-1 (p.p.b.) at 14 days to 11.0 +/- 4.7 micrograms l-1 at 49 days. Faecal ivermectin concentrations were little changed from 4.0 +/- 2.0 micrograms g-1 (p.p.m.) dry wt (dry weight) [0.5 +/- 0.2 microgram g-1 wet wt (wet weight)] at 14 days to 3.0 +/- 2.0 micrograms g-1 dry wt (0.5 +/- 0.4 microgram g-1 wet wt) at 49 days. Group 2 (Pour-on) cows showed a rapid rise in plasma concentrations to 32.9 +/- 15.7 micrograms l-1 2 days after treatment, followed by a gradual decline to 1.3 +/- 0.07 micrograms l-1 at 28 days. Faecal ivermectin concentrations rose sharply to 18.5 +/- 7.4 micrograms g-1 dry wt (2.8 +/- 1.2 micrograms g-1 wet wt) 2 days after treatment, then fell to 0.04 +/- 0.004 microgram g-1 dry wt (0.006 +/- 0.0004 microgram g-1 wet wt) at 28 days. Group 3 (Injection) cows also showed a rapid rise to an early plasma peak of 46.1 +/- 22.7 micrograms l-1 3 days after treatment, followed by a gradual decline to 1.3 micrograms l-1 at 35 days. Faecal ivermectin concentrations rose to 1.2 +/- 0.34 micrograms g-1 dry wt (0.2 +/- 0.05 microgram g-1 wet wt) at 3 days, declining to 0.08 +/- 0.0001 microgram g-1 dry wt (0.01 +/- 0.0008 microgram g-1 wet wt) at 28 days. No ivermectin was detected in the plasma or faeces of Group 4 (Control) cows. Concentrations of ivermectin potentially toxic to dung-breeding or dung-feeding invertebrates were excreted for the duration of the study in dung of cows treated with the SR Bolus and for 28 days in the dung of cows treated with the Pour-on or injectable formulations.
16头年轻奶牛被随机分为4组，每组4头：第1组奶牛每头注射一剂伊维菌素缓释丸剂；第2组奶牛用伊维菌素浇泼剂处理；第3组奶牛注射伊维菌素皮下注射液；第4组奶牛为未处理的对照组。在处理前一天以及处理后的第1、2、3、7、14、21、28、35、42和49天，从所有奶牛采集血液和粪便样本，用于高效液相色谱法测定血浆和粪便中伊维菌素的浓度。第1组（缓释丸剂）奶牛的血浆伊维菌素平均浓度（±标准差）在14天时为5.6±1.8微克/升（十亿分比），到49天时为11.0±4.7微克/升。粪便中伊维菌素浓度变化不大，从14天时的4.0±2.0微克/克干重（百万分比）[0.5±0.2微克/克湿重]到49天时的3.0±2.0微克/克干重（0.5±0.4微克/克湿重）。第2组（浇泼剂）奶牛在处理后2天血浆浓度迅速升至32.9±15.7微克/升，随后逐渐下降，到28天时降至1.3±0.07微克/升。粪便中伊维菌素浓度在处理后2天急剧升至18.5±7.4微克/克干重（2.8±1.2微克/克湿重），然后在28天时降至0.04±0.004微克/克干重（0.006±0.0004微克/克湿重）。第3组（注射剂）奶牛在处理后3天也迅速升至早期血浆峰值46.1±22.7微克/升，随后逐渐下降，到35天时降至1.3微克/升。粪便中伊维菌素浓度在3天时升至1.2±0.34微克/克干重（0.2±0.05微克/克湿重），在28天时降至0.08±0.0001微克/克干重（0.01±0.0008微克/克湿重）。第4组（对照组）奶牛的血浆或粪便中未检测到伊维菌素。在用缓释丸剂处理的奶牛粪便中，在整个研究期间都排泄出了对粪便繁殖或粪便摄食无脊椎动物具有潜在毒性的伊维菌素浓度；在用浇泼剂或注射剂处理的奶牛粪便中，在28天内排泄出了该浓度。
