Abstract
Moxidectin, a newly developed endectocide, has previously been demonstrated to have a high efficacy against gastrointestinal nematodes in cattle (Ranjan et al. 1992, Scholl et al. 1992). In a field trial (Yang, Satrija and Nansen, unpublished data) matched groups of 8 first-season Black Pied Friesian heifer calves, 6-8 months of age, were turned out in early May 1992 on a permanent pasture contaminated with trichostrongyles. The groups were grazed separately on comparable plots until they were housed in mid October 1992. Group Β was treated with moxidectin at turnout, and group C was treated at turnout and again 8 weeks after turnout. A third group served as non-treated controls (group A). The results showed that the 2 early season prophylactic treatments (group C) reduced the late season herbage trichostrongyle larval infectivity with 80 to 90%, whereas the reduction accomplished by only 1 treatment at turnout (group B) was much less. Group C excreted significantly lower numbers of strongyle eggs than groups A and B. The non-treated controls showed clinical signs of trichostrongylosis in late September, which coincided with a steep rise in serum pepsinogen levels reaching an average peak level of 3.5 IU tyrosine litre-1. A few animals in group Β showed softening of faeces particularly in the very late season. In contrast, animals receiving 2 moxidectin treatments remained in a clinically good condition throughout the season.
Full Text
The Full Text of this article is available as a PDF (909.1 KB).
References
- Armour J, Bairden K, Duncan JL, Jennings FW, Parkins J J. Observations on ostertagiasis in young cattle over two grazing seasons with special reference to plasma pepsinogen levels. Vet. Rec. 1979;105:500–503. doi: 10.1136/vr.105.22.500. [DOI] [PubMed] [Google Scholar]
- Chalmer K. Serum pepsinogen levels and Ostertagia ostertagi population in clinically normal adult beef cattle. N.Z. vet. J. 1983;31:189–191. doi: 10.1080/00480169.1983.35024. [DOI] [PubMed] [Google Scholar]
- Jacobs DE, Pitt SR, Foster J, Fox MT. Interactions between chemoprophylaxis and immunity to bovine parasitic gastroenteritis and bronchitis: pilot studies using an oxfendazole pulse release blus. Res. vet. Sci. 1987;43:273–275. [PubMed] [Google Scholar]
- Jacobs DE, Foster J, Gowling G, Pilkington JG, Fox MT, Ryan MT. Comparative study of early-season prophylaxis using ivermectin with lungworm vaccination in the control of parasitic bronchitis and gastroenteritis in cattle. Vet. Parasitol. 1989;34:45–56. doi: 10.1016/0304-4017(89)90163-5. [DOI] [PubMed] [Google Scholar]
- Nansen P, Grønvold J, Jørgensen RJ, Henriksen SA, Foldager J, Sejrsen K. Outbreaks of early-season trichostrongylosis in calves in Denmark. Vet. Parasitol. 1989;32:199–211. doi: 10.1016/0304-4017(89)90121-0. [DOI] [PubMed] [Google Scholar]
- Ranjan S, Trudeau C, Prichard RK, Kutzleben R v, Carrier D. Efficacy of moxidectin against naturally acquired nematode infections in cattle. Vet. Parasitol. 1992;41:227–231. doi: 10.1016/0304-4017(92)90082-k. [DOI] [PubMed] [Google Scholar]
- Ross JG, Pur c D, Dow C, Todd JR. Experimental infection of calves with Trichostrongylus axei: The course of development of infection and lesions in low level infections. Res. vet. Sci. 1967;8:201–206. [PubMed] [Google Scholar]
- Satrija F. The effect of avermectin treatment on performance and immunity in calves during their first and second season grazing. Copenhagen: Royal Veterinary and Agricultural University; 1993. p. 159. [Google Scholar]
- Scholl PJ, Guillot FS, Wang GT. Moxidectin: systemic activity against common cattle grups (Hypoderma lineatum) (Diptera: Oestridae) and trochostrongyle nematodes in cattle. Vet. Parasitol. 1992;41:203–209. doi: 10.1016/0304-4017(92)90080-s. [DOI] [PubMed] [Google Scholar]