The effect of strategic anthelmintic treatment on the breeding performance of hill ewes

A series of field trials involving 3500 Scottish hill ewes was carried out to determine the effect of different worming routines on subsequent flock performance. Combinations of the following seasonal dosings were examined in April lambing flocks: “early winter” (November/early December); “winter” (mid-January to early February) and “spring” (mid-March to early April). The effects upon numbers of barren ewes and on rearing percentages in comparison with untreated control sheep were evaluated.Barrenness was significantly reduced by the following treatments: “early winter” by 70% (P<0.10); “winter” by 7.8% (P<0.05); “early winter and winter” by 4.3% (P<0.05). Rearing percentages were significantly increased by the following treatments: “early winter and winter” by 10.7% (P<0.01); “early winter and spring” by 9.2% (P<0.01); “spring” by 7.9% (P<0.05).The increased rearing percentages indicated that a strategic dosing programme for breeding ewes between mating and parturition is worthwhile, with the routines involving two doses — either ”early winter and winter” and “early winter and spring” giving the greatest benefit.Attention is drawn to the high incidence of barrenness and low rearing percentages which was a constant feature in all the flocks used in the trial.     

Very low helminth infection in sheep grazed on pastures fertilised by sewage sludge or cattle slurry

Helminth infection acquired by lambs grazing on pastures fertilised either by urban sewage sludge or cattle slurry were studied in temperate Central Western France. The aim was to assess the risk of larval cestodoses in lambs after sewage application and of digestive tract nematode infection following the slurry application. Twenty-six sheep were allocated on two paddocks of 0.7 ha, one fertilised with sludge and the other with cattle slurry. The delay between application and actual grazing was 6 weeks; grazing on these paddocks extended from mid July to beginning of November 2002. The herbage biomass was slightly increased in the sludge paddock but it did not result in an increase of lamb live weight, compared with the slurry paddock. The lambs did not acquire cysticercosis or any other larval cestodoses in the sewage sludge group and only very limited infections with Cooperia spp. and Nematodirus spp. were observed in the slurry group. It was concluded that in our conditions the helminth risk was extremely low and was not a cause of restriction of the use of these biowastes.     

Effect of a single dry season anthelmintic treatment of N'Dama cattle on communal pastures in The Gambia

The effect of a single anthelmintic treatment of cattle during the early dry season was studied. One hundred and sixty-six N'Dama cattle, 1–3 years old, were selected from five herds. There were 65 males and 101 females divided into two groups of 83 animals each. One group was treated with fenbendazole at 7.5 mg/kg body weight by mouth in November 1992; the other group remained as the untreated control. At monthly intervals from November 1992 to April 1993, each animal was weighed and the number of eggs/g of faeces (epg) was determined. The infective larvae (L3) were examined following culture of pooled samples from each group of animals. In April 1993, 6 animals (3 treated and 3 controls) from the herds under study were necropsied. The difference in the weight gains (4.6 kg) of the two groups was highly significant (p<0.0001). The difference in the weight gains and the epg between the treated and control groups was influenced by the age of the animals. Of the treated animals, one contained no nematodes, one contained only 25Oesophagostomum radiatum, and the third contained 25Cooperia L4. The three untreated animals were all infected. It was concluded that the treatment in early dry season, with an anthelmintic effective against both adults and larvae, led to a significant reduction in egg counts, to elimination of adults and hypobiotic larvae and, consequently, to an increase in the body weight gain by the treated animals.     

Effect of anthelmintic treatment on the performance of awassi sheep in Iraq

Summary Studies are reported on the effect of anthelmintic treatment on the body weight gain and wool growth of ewes with subclinical helminth infections. The parasites involved wereFasciola gigantica andOstertagia spp., together with someHaemonchus contortus,Trichostrongylus spp., andDictyocaulus filaria.In 1 group, 5 sheep, which were treated twice with tetramisole at an interval of 4 weeks to remove gastro-intestinal nematodes and lungworms, showed an increase of 41% in weight gain and 3·2% in wool growth compared with an untreated group.Another group, which was treated with both tetramisole and rafoxanide to remove nematode and fluke infections, had a 143% increase in weight gain and 81% in wool growth compared with the control.

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Efectos Del Tratamiento Con Antihelminticos En La Productividad De Ovejas Awassi En Irak

Resumen Se describen los resultados de estudios sobre los efectos del tratamiento con antihelmínticos de infecciones subclínicas en ovejas Awassi, en relación con el aumento de peso y crecimiento de lana. Los parásitos involucrados fueronFasciola gigantica yOstertagia spp., junto conTrichostrongylus spp. yDictyocaulus filaria.En 1 grupo, 5 ovejas que recibieron doble tratamiento con tetramisole a intervalos de 4 semanas contra nemátodos gastro-intestinales y parásitos pulmonares, tuvieron un incremento del 41% en peso y 3·2% en crecimiento de lana, sobre el grupo control sin tratamiento.Otro grupo en el cual los animales se trataron con tetramisole y rafoxanide contra nemátodos y fasciola, tuvieron un incremeto del 143% en peso y 81% en crecimiento de lana, sobre el grupo control.

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Effets De Traitements Anthelminthiques Sur Les Performances Du Mouton Awassi En Irak

Résumé Les études ont porté sur les effets de divers traitements anthelminthiques au plan du gain de poids et de la production de larves chez des brebis atteintes d'infections subcliniques.Les parasites concernés étaientFasciola gigantica etOstertagia spp. associés avec quelquesHaemonchus contortus,Trichostronglyus spp., etDictyocaulus filaria.Dans un premier groupe, 5 brebis qui ont été traitées à deux reprises avec du tétramisole, à un intervalle de quatre semaines, contre des nématodes gastro-intestinaux et des helminthes pulmonaires ont accusé un gain de poids de 41 p. 100 et de 3,2 p. 100 pour la laine par rapport à ceux du groupe non traité.Un autre groupe qui a été traité à la fois avec du tétramisole et du rafoxanide contre les nématodes et les douves a accusé une augmentation de poids de l'ordre de 143 p. 100 et de 81 p. 100 en ce qui concerne la laine en comparaison avec des animaux témoins.

     

Effect of anthelmintic treatment on the performance of Awassi sheep in Iraq

Studies are reported on the effect of anthelmintic treatment on the body weight gain and wool growth of ewes with subclinical helminth infections. The parasites involved were Fasciola gigantica and Ostertagia spp., together with some Haemonchus contortus, Trichostrongylus spp., and Dictyocaulus filaria. In 1 group, 5 sheep, which were treated twice with tetramisole at an interval of 4 weeks to remove gastro-intestinal nematodes and lungworms, showed an increase of 41% in weight gain and 3.2% in wool growth compared with an untreated group. Another group, which was treated with both tetramisole and rafoxanide to remove nematode and fluke infections, had a 143% increase in weight gain and 81% in wool growth compared with the control.     

Population dynamics of Trichostrongylus colubriformis in sheep following anthelmintic treatment

Three groups of five, three-and-a-half to four-month-old lambs were put to graze on three plots contaminated by Trichostrongylus colubriformis. One group (control) was free of parasites, while the other two were infected just before turning out with 3 X 700 third stage larvae. Depending on whether or not the lambs were treated with 50 mg kg-1 thiabendazole nine days after the first infection, the worm burden and the egg output increased or decreased during the grazing period when compared with the control group. In tracer animals put to graze on the same plots afterwards, it was found that the smaller the number of eggs excreted by the first lambs, the higher were the worm burdens of the tracer lambs.     

The rapid appearance of anthelmintic resistance on a sheep farm

A sudden outbreak of perinatal mortality in piglets occurred between May and August 1991 in a 60-sow piggery near Palmerston North. None of the piglets born to the 30 sows which farrowed during this period of time survived more than a few days and all live-born piglets appeared weak. Three newborn live piglets were humanely killed and at necropsy had marked diffuse subcutaneous oedema, the only gross and histological anomalies detected in the extensive range of tissues examined. Serological tests of sows were negative for leptospiral, porcine herpes viral (Aujeszky's), porcine parvoviral, encephalomyocarditis viral and Brucelh suis infections. No viral agents were recovered on cell culture from pooled piglet tissues. Liver selenium levels were normal, but Vitamin E values (0.8, 0.8 and 0.6 μmol/kg respectively) seemed low according to the recently established range of 0.9-1.4 μmol/kg for normal unsuckled piglets in New Zealand⁽¹⁾. No Vitamin E/selenium deficiency syndromes had been recognised previously in this herd.     

The persistence of the anthelmintic activity of ivermectin in sheep

The persistent anthelmintic effect of subcutaneously and orally administered ivermectin given at a dose rate of 0.2 mg/kg was evaluated against experimentally induced infections of Haemonchus contortus, Ostertagia spp., Trichostrongylus spp. and Cooperia curticei in sheep. While both ivermectin treatments apparently resulted in some reduction in the establishment of most of the parasite species examined, only for C. curticei were these reductions statistically significant. For C. curticei, statistically significant antiparasitic activity was evident in animals five and ten days after treatment with ivermectin given by injection and five days after treatment with ivermectin given orally. The possible relevance of these results to parasite control and the potential for selecting for anthelmintic resistance are briefly discussed.     

The rate of recovery of intestinal morphology following anthelmintic treatment of parasitised sheep.

Sixteen sheep which had previously been infected with Ostertagia circumcincta were dosed with 4000 Trichostrongylus colubriformis larvae/day for four weeks, then given anthelmintic and killed at intervals thereafter. Histological examination of the small intestine showed that two to three weeks were required for restoration of a normal mucosal architecture.     

Effects of an anthelmintic treatment programme on sheep productivity in the Middle Atlas,Morocco

Summary This study evaluated the production advantages of the strategic anthelmintic treatment of both lambs and ewes in an area endemic for gastro-intestinal nematodes, lungworms and liver flukes. The liver fluke infections were generally chronic. The lambs were treated with albendazole (SmithKline Beecham), fenbendazole (Hoechst Roussel) or a vitamin supplement and their weight gains were followed over the next 7 months. The control group, which received a vitamin supplement only, gained 6·67 kg from July to January. The group that received fenbendazole, an anthelmintic with no activity against liver flukes, gained 10·42 kg over the study period. The third group which received albendazole, an anthelmintic with efficacy against liver flukes, gained 13·07 kg over the same period. Lamb deaths apparently due to liver flukes were 12, 4, and zero for the control, fenbendazole and albendazole groups, respectively. Similar advantages were observed in the ewes. Deaths were 16, 8, and zero in the control, fenbendazole and albendazole groups, respectively. The lambing rate in the control groupswas significantly lower than that in either of the 2 treated groups. The number of services per conception was significantly lower in the albendazole treated group than that in either of the other groups. These studies demonstrated the advantages of anthelmintic treatment in sheep in a helminth endemic area. While removing gastro-intestinal nematodes and lungworms improved production, the additional removal of liver flukes enhanced production gains as well as reducing deaths.

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Resumen Este estudio evaluó las ventajas de un tratamiento estratégico en corderos y ovejas en un área endémica de parásitos gastrointestinales, pulmonares y hepáticos. La infección con fasciola era crónica. Los corderos fueron tratados con albendazole (Smithkline Beecham), fenbendazole (Hoechst Roussel) o un suplemento vitamínico; el peso fue consignado durante 7 meses seguidos. El grupo control que recibió el suplemento vitamínico, ganó 6·67 kg desde julio hasta enero. El grupo que recibió fenbendazole, antihelmíntico sin acción contra la fasciola, ganó 10·42 kg durante el período de estudio. El tercer grupo que recibió albendazole, un antihelmíntico eficaz contra la fascioliasis, ganó 13·7 kg durante el mismo período. La mortalidad de los corderos aparentemente debida a fascioliasis fue de 12 animales, 4 animales y cero animales, en el grupo control, en el tratado con fenbendazole y en el tratado con albendazole, respectivamente. En ovéjas, las ventajas fueron similares. La mortalidad por fascioliasis fue de 16 animales, 8 animales y cero animales, en el grupo control, en el tratado con fenbendazole y en el tratado con albendazole, respectivamente. La tasa de pariciones en el grupo control, fue significativamente más baja, que aquella de los grupos tratados. El número de servicios por concepción fue menor en el grupo tratado con albendazole. Estos estudios demostraron, la ventaja de los tratamientos antihelmínticos en ovejas en áreas endémicas. Mientras que el tratamiento contra parásitos gastrointestinales y pulmonares mejoró la producción, el tratamiento contra fasciola mejoró las ganancias de peso y redujo las muertes.

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Résumé Cette étude évalue les avantages en matière de production d’une stratégie de traitements anthelminthiques des brebis et des agneaux dans une zone endémique pour les nématodes gastro-intestinaux, les Fasciola et les strongles pulmonaires. Les infections à Fasciola ont généralement un caractère chronique. Les agneaux ont été traités soit à l’albendazole (SmithKline, Beecham) ou au fenbendazole (Hoechst Roussel) ou avec un complément vitaminé. Leur gain de poids ont été suivis pendant les sept mois suivants. Le groupe des témoins qui n’a re?u qu’un complément vitaminé a gagné 6,67 kg de juillet à janvier. Celui traité au fenbendazole, anthelminthique dépourvu d’activité contre les douves a progressé de 10,42 kg pendant la période d’étude. Le troisième groupe a été traité à l’albendazole, produit actif contre les Fasciola. Il a gagné quant à lui 13,07 kg au cours du même laps de temps. La mortalité des agneaux, due apparemment aux douves a été pour les groupes témoins et fenbendazole et albendazole respectivement de 12,4 et zéro. Des avantages identiques ont été observés pour les brebis dont la mortalité a été de 16,8 et zéro respectivement pour les lots témoins et fenbendazole et albendazole. Le taux d’agnelage dans le groupe témoin a été significativement plus bas que celui de l’un et de l’autre des deux groupes traités. Le nombre d’accouplements par conception était significativement plus bas dans le lot traité à l’albendazole que dans n’importe lequel des autres lots. Ces facteurs confirment les avantages d’un traitement anthelminthique chez les ovins vivants dans une région de parasitisme endémique. Tandis que la production est améliorée par la suppression des nématodes gastro-intestinaux et des strongles pulmonaires, la disparition complémentaire des douves accro?t les gains de production au même titre qu’elle réduit la mortalité.

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This work was supported in part by the International Foundation for Science (Stockholm).     

An assessment of the effects of ruminal selenium pellets given to young sheep grazing selenium-deficient pastures

Thirty-eight species of small cetaceans termed “dolphins” and “porpoises” are listed. This review is a contribution to the growing community and veterinary interest in the welfare and diseases of these animals.