Targeted anthelmintic treatment of parasitic gastroenteritis in first grazing season dairy calves using daily live weight gain as an indicator
| Autor: | Nicholas N. Jonsson, J. McGoldrick, Michael J. Stear, Andrew Forbes, A. Jackson, Kathryn Ellis |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Parasitic gastroenteritis Veterinary medicine Nematoda 040301 veterinary sciences Live weight Cattle Diseases Eprinomectin Biology Weight Gain Pasture 0403 veterinary science 03 medical and health sciences Feces Farm level Pepsinogen A Grazing medicine Animals Anthelmintic Intestinal Diseases Parasitic Nematode Infections Parasite Egg Count Anthelmintics geography geography.geographical_feature_category Ivermectin General Veterinary 04 agricultural and veterinary sciences General Medicine 030108 mycology & parasitology Gastroenteritis Dairying Feasibility Studies Parasitology Cattle Female medicine.symptom Weight gain medicine.drug |
| Zdroj: | Veterinary parasitology. 244 |
| ISSN: | 1873-2550 |
| Popis: | Control of parasitic gastroenteritis in cattle is typically based on group treatments with anthelmintics, complemented by grazing management, where feasible. However, the almost inevitable evolution of resistance in parasitic nematodes to anthelmintics over time necessitates a reappraisal of their use in order to reduce selection pressure. One such approach is targeted selective treatment (TST), in which only individual animals that will most benefit are treated, rather than whole groups of at-risk cattle. This study was designed to assess the feasibility of implementing TST on three commercial farms, two of which were organic. A total of 104 first-grazing season (FGS), weaned dairy calves were enrolled in the study; each was weighed at monthly intervals from the start of the grazing season using scales or weigh-bands. At the same time dung and blood samples were collected in order to measure faecal egg counts (FEC) and plasma pepsinogen, respectively. A pre-determined threshhold weight gain of 0.75 kg/day was used to determine those animals that would be treated; the anthelmintic used was eprinomectin. No individual animal received more than one treatment during the grazing season and all treatments were given in July or August; five animals were not treated at all because their growth rates consistently exceeded the threshold. Mean daily live weight gain over the entire grazing season ranged between 0.69 and 0.82 kg/day on the three farms. Neither FEC nor pepsinogen values were significantly associated with live weight gain. Implementation of TST at farm level requires regular (monthly) handling of the animals and the use of weigh scales or tape, but can be integrated into farm management practices. This study has shown that acceptable growth rates can be achieved in FGS cattle with modest levels of treatment and correspondingly less exposure of their nematode populations to anthelmintics, which should mitigate selection pressure for resistance by increasing the size of the refugia in both hosts and pasture. |
| Databáze: | OpenAIRE |
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