Advantage of Parasite Control with IVOMEC EPRINEX (eprinomectin) When Processing Wet Cattle

Transcription

1 Advantage of Parasite Control with IVOMEC EPRINEX (eprinomectin) When Process.. Page 1 of 5 More Information About This Topic From Merial: Bovine Fecal Exam Limitations D. Briskey Merial Veterinary Bulletin TSB FTB Facts and Fecals D. Carithers Merial Veterinary Bulletin TSB FTB TSB FTB Advantage of Parasite Control with IVOMEC EPRINEX (eprinomectin) When Processing Wet Cattle Jay R. Brown, DVM, MS Based on: Cruthers L, Slone R. Comparative efficacy of commercial pour-on parasiticides applied to wet cattle, in Proceedings. 44th Ann Meeting AAVP, 1999; #29. Introduction Cattle producers in a wide variety of geographies are faced with the possibility of working their cattle when the weather may be unpredictable, or of receiving cattle for processing which have been exposed to recent rainfall. Currently, there are three pour-on endectocides on the market whose labels address the use of each product with respect to rainfall. These products are IVOMEC EPRINEX (eprinomectin) Pour-On for Beef and Dairy Cattle, DECTOMAX (doramectin) Pour-On, and CYDECTIN (moxidectin) Pour-On. The question of which product is the best to use in the event of rainfall may be asked of veterinarians and animal health providers. To help answer this question, the efficacy of IVOMEC EPRINEX and DECTOMAX Pour-On was evaluated in a controlled, double-blind study in cattle naturally infected with gastrointestinal nematodes and exposed to simulated rainfall before treatment. IVOMEC and EPRINEX areregistered trademarks of Merial. DECTOMAX is a registered trademark of Pfizer Inc. CYDECTIN is a registered trademark of American Cyanamid Company Merial Limited. All rights reserved. The Bottom Line! Even when applied as soon as 5 minutes after 43 minutes of simulated rainfall, IVOMEC EPRINEX was more than 99% effective against adults and immature larvae (L4) of Ostertagia spp., Trichostrongylus axei, Cooperia spp., and adult Haemonchus placei, Nematodirus helvetianus, Trichostrongylus colubriformis, Oesophagostomum radiatum and Trichuris spp.! Cattle treated with IVOMEC EPRINEX had significantly (P<0.01) fewer adult worms overall and total worm burden than cattle treated with DECTOMAX Pour-On.! IVOMEC EPRINEX maintained a superior level of efficacy in killing (>99%) the total number of worms compared to DECTOMAX Pour-On (94.9%), even on cattle that had been subjected to simulated rain shortly before application, confirming its flexibility and convenience.

2 Advantage of Parasite Control with IVOMEC EPRINEX (eprinomectin) When Process.. Page 2 of 5 The Trial Eighteen naturally-infected crossbred beef stocker calves, with equal numbers of both sexes and weighing approximately 300 to 650 lb each, were used. Each calf was identified with a unique eartag number. A fecal egg count using the McMaster technique was performed on a fecal sample from each calf. The calves were then allocated by restricted randomization based on fecal egg counts within sex to the following treatment groups: 1. Untreated control 2. IVOMEC EPRINEX Pour-On for Beef and Dairy Cattle 3. DECTOMAX Pour-On for Cattle Both products were administered at a dosage of 500 mcg active compound/kg once topically on Day 0. There were two replicates per treatment group, with six calves per replicate. After a 2-week acclimation period, all of the calves were exposed to approximately 1 inch of simulated rain for 43 to 44 minutes, equal to a rate of about 1.3 inch per hour. Each calf was then treated 5 to 20 minutes following the wetting process. The study was blinded by assigning codes to each group and treatment. The calves were maintained in concrete-floored, covered pens for the duration of the study to prevent any further exposure to nematode infection, as well as to prevent any further potential exposure to rainfall. Fecal egg counts were conducted on each calf at weekly intervals up to Day 21. Calves from Replicate 1 were necropsied on Day 28 and those from Replicate 2 were necropsied on Day 30. Nematode counts were performed on the total contents of the large intestine and on 5% aliquots of the abomasum and small intestine. Results Cattle treated with IVOMEC EPRINEX as soon as 5 minutes after 43 minutes of simulated rainfall had significantly (P<0.01) fewer adult and total worm burdens than cattle treated with DECTOMAX Pour-On. Worm counts from the necropsies performed on the cattle are displayed in Figure 1. At Day 21, there were no significant differences in average fecal egg counts between groups treated with IVOMEC EPRINEX (1.2) or with DECTOMAX Pour-On (23.2); however, both treatments were significantly different (P<0.01 and P<0.05, respectively) from the control group (Figure 2). Discussion

3 Advantage of Parasite Control with IVOMEC EPRINEX (eprinomectin) When Process.. Page 3 of 5 A major goal of any antiparasitic treatment program is to effectively control as many parasites as possible, with timing that makes the greatest impact. Status of the cattle, pasture, weather and season need to be considered. The parasite life cycles and the effect of larval stages must be evaluated to determine the most effective antiparasitic program. A "standard" antiparasitic program is not always going to be the most effective. However, a highly effective, broad-spectrum parasite control product that provides flexibility and convenience will allow optimal control even in the face of variations in the weather and pasture conditions. Figure 1. Average worm recoveries from calves treated with IVOMEC EPRINEX or DECTOMAX Pour-On following exposure to simulated rainfall (a,b) Means for variables with different superscripts are significantly different (P<0.01) No. of adult worms from control group=11,386 Total worm burden from control group=17,043 * Geometric Mean Figure 2. Average Day 21 nematode egg counts for calves treated with IVOMEC EPRINEX or DECTOMAX Pour-On following exposure to simulated rainfall

4 Advantage of Parasite Control with IVOMEC EPRINEX (eprinomectin) When Process.. Page 4 of 5 (a) Significantly different from control (P<0.01) (b) Significantly different from control (P<0.05) *Geometric Mean In this study, IVOMEC EPRINEX was significantly (P<0.01) more effective in killing the total number of worms (>99%) compared to DECTOMAX Pour-On (94.9%) when applied to cattle 5 to 20 minutes after simulated rain. The net effect of higher worm burdens is resumed egg laying, thereby increasing pasture contamination and resumed buildup of gastrointestinal parasites in the animal and on the pasture. Pasture contamination can lead to productivity losses via future re-infection of grazing cattle. Data from this study would indicate that IVOMEC EPRINEX, with its higher efficacy and broader spectrum features, provides advantages when one must contend with rainfall prior to the administration of pour-on endectocides. Conclusion In comparison to DECTOMAX Pour-On, this study showed that cattle treated with IVOMEC EPRINEX had significantly lower total worm burdens than cattle treated with DECTOMAX Pour-On. IVOMEC EPRINEX maintained a superior level of efficacy (>99%) in killing the total number of worms compared to DECTOMAX Pour-On (94.9%), even on cattle that had been subjected to simulated rain shortly before application, confirming its flexibility and convenience.

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