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 | Acesso ao texto completo restrito à biblioteca da Embrapa Caprinos e Ovinos. Para informações adicionais entre em contato com cnpc.biblioteca@embrapa.br. |
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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
27/12/2016 |
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Data da última atualização: |
20/02/2026 |
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Autoria: |
CALLINAN, A. P. L.; MORLEY, F. H. W.; ARUNDEL, J. H.; WHITE, D. H. |
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Título: |
A model of the life cycle of sheep nematodes and the epidemiology of nematodiasis in sheep. |
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Ano de publicação: |
1982 |
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Fonte/Imprenta: |
Agricultural Systems, v. 9, n. 3, p. 199-225, Nov. 1982. |
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DOI: |
https://doi.org/10.1016/0308-521X(82)90020-8 |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: A computer model (NEMAT) of the life cycle of sheep nematodes and of the epidemiology of nematodiasis in sheep was constructed. Its purpose is to predict the development of nematodiasis in weaner sheep and to determine optimum nematode control programmes. It has been developed for use in western Victoria, Australia, but it should also be of use in other localities. NEMAT simulates the growth of perennial ryegrass (Lolium perenne) and subterranean clover (Trifolium subterraneum) pasture and weaner sheep and the development of populations of the sheep nematodes Ostertagia spp. and Trichostrongylus spp. The development and death rate parameters of the free-living stages of these nematodes were estimated by a direct search optimisation procedure specifically developed for this study. The death rates of the parasitic stages of Ostertagia spp. were determined in a field experiment and expressed as a function of the rate of infection and the time of exposure to infection. Other probability density functions and deterministic functions needed to complete the quantification of the sheep-nematode system were derived from published reports or personal communications. NEMAT was validated against data from two independent field experiments carried out in western Victoria. Predicted serial measurements of pasture availability, liveweights, total nematode counts, nematode eggs per gram of faeces and numbers of infective nematode larvae per hectare were compared with those actually observed. The predicted and observed measurements were subjectively similar and could not be differentiated statistically by spectral analysis. NEMAT was then used to evaluate some nematode control programmes in western Victoria. Using observed weather data, it simulated the continuous development of nematode populations during 1957?1976 on pastures set stocked on the 1st of January each year with recently drenched weaner sheep. If sheep were drenched in only one month of the year, the effect of this drench on liveweights and woolweights at the end of the year was greatest if it was given in February. There was a progressive decline in final liveweights and woolweights if it was given in subsequent months to December. If sheep were drenched in February and given a second drench in any one of the remaining months of the year, the effects of this second drench on final liveweights and woolweights was greatest if it was given at the autumn break. A drench in February and a drench and shift to ?clean? pasture (<104 nematode larvae per hectare) in July were always sufficient to limit the mean yearly effects of nematodiasis to 1 kg in liveweight and 0·1 kg in woolweight. When such a shift was not possible, a drench in February, another at the autumn break and 0?5 drenches in winter and spring were required to attain similar productivity. The number and timing of these drenches after the autumn break depended on the daily effects of weather on the nematode population and could be determined only by a model of the sheep-nematode system such as NEMAT. MenosAbstract: A computer model (NEMAT) of the life cycle of sheep nematodes and of the epidemiology of nematodiasis in sheep was constructed. Its purpose is to predict the development of nematodiasis in weaner sheep and to determine optimum nematode control programmes. It has been developed for use in western Victoria, Australia, but it should also be of use in other localities. NEMAT simulates the growth of perennial ryegrass (Lolium perenne) and subterranean clover (Trifolium subterraneum) pasture and weaner sheep and the development of populations of the sheep nematodes Ostertagia spp. and Trichostrongylus spp. The development and death rate parameters of the free-living stages of these nematodes were estimated by a direct search optimisation procedure specifically developed for this study. The death rates of the parasitic stages of Ostertagia spp. were determined in a field experiment and expressed as a function of the rate of infection and the time of exposure to infection. Other probability density functions and deterministic functions needed to complete the quantification of the sheep-nematode system were derived from published reports or personal communications. NEMAT was validated against data from two independent field experiments carried out in western Victoria. Predicted serial measurements of pasture availability, liveweights, total nematode counts, nematode eggs per gram of faeces and numbers of infective nematode larvae per hectare were compared with those actuall... Mostrar Tudo |
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Thesagro: |
Modelo de simulação; Modelo matemático; Nematóide; Ovino. |
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Thesaurus Nal: |
Mathematical models; Nematoda; Sheep; Simulation models. |
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Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
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Marc: |
LEADER 03869naa a2200265 a 4500
001 2059377
005 2026-02-20
008 1982 bl uuuu u00u1 u #d
024 7 $ahttps://doi.org/10.1016/0308-521X(82)90020-8$2DOI
100 1 $aCALLINAN, A. P. L.
245 $aA model of the life cycle of sheep nematodes and the epidemiology of nematodiasis in sheep.$h[electronic resource]
260 $c1982
520 $aAbstract: A computer model (NEMAT) of the life cycle of sheep nematodes and of the epidemiology of nematodiasis in sheep was constructed. Its purpose is to predict the development of nematodiasis in weaner sheep and to determine optimum nematode control programmes. It has been developed for use in western Victoria, Australia, but it should also be of use in other localities. NEMAT simulates the growth of perennial ryegrass (Lolium perenne) and subterranean clover (Trifolium subterraneum) pasture and weaner sheep and the development of populations of the sheep nematodes Ostertagia spp. and Trichostrongylus spp. The development and death rate parameters of the free-living stages of these nematodes were estimated by a direct search optimisation procedure specifically developed for this study. The death rates of the parasitic stages of Ostertagia spp. were determined in a field experiment and expressed as a function of the rate of infection and the time of exposure to infection. Other probability density functions and deterministic functions needed to complete the quantification of the sheep-nematode system were derived from published reports or personal communications. NEMAT was validated against data from two independent field experiments carried out in western Victoria. Predicted serial measurements of pasture availability, liveweights, total nematode counts, nematode eggs per gram of faeces and numbers of infective nematode larvae per hectare were compared with those actually observed. The predicted and observed measurements were subjectively similar and could not be differentiated statistically by spectral analysis. NEMAT was then used to evaluate some nematode control programmes in western Victoria. Using observed weather data, it simulated the continuous development of nematode populations during 1957?1976 on pastures set stocked on the 1st of January each year with recently drenched weaner sheep. If sheep were drenched in only one month of the year, the effect of this drench on liveweights and woolweights at the end of the year was greatest if it was given in February. There was a progressive decline in final liveweights and woolweights if it was given in subsequent months to December. If sheep were drenched in February and given a second drench in any one of the remaining months of the year, the effects of this second drench on final liveweights and woolweights was greatest if it was given at the autumn break. A drench in February and a drench and shift to ?clean? pasture (<104 nematode larvae per hectare) in July were always sufficient to limit the mean yearly effects of nematodiasis to 1 kg in liveweight and 0·1 kg in woolweight. When such a shift was not possible, a drench in February, another at the autumn break and 0?5 drenches in winter and spring were required to attain similar productivity. The number and timing of these drenches after the autumn break depended on the daily effects of weather on the nematode population and could be determined only by a model of the sheep-nematode system such as NEMAT.
650 $aMathematical models
650 $aNematoda
650 $aSheep
650 $aSimulation models
650 $aModelo de simulação
650 $aModelo matemático
650 $aNematóide
650 $aOvino
700 1 $aMORLEY, F. H. W.
700 1 $aARUNDEL, J. H.
700 1 $aWHITE, D. H.
773 $tAgricultural Systems$gv. 9, n. 3, p. 199-225, Nov. 1982.
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| 2. |  | CUNHA JÚNIOR, P. C.; OLIVEIRA, L. DE S. DE; BLANCO, J. C.; SILVA, M. T. DE C.; GÁLVEZ, S. G. L.; ROSENTHAL, A.; FERREIRA, E. H. DA R. Elaboration, characterization, and probiotic viability of synbiotic non-dairy drink based on coconut. Ciência Rural, v. 53, n. 3, e20210723, p. 1-5, 2023. Elaboração, caracterização e viabilidade probiótica de bebida simbiótica não-láctea a base de coco.| Tipo: Artigo em Periódico Indexado | Circulação/Nível: A - 2 |
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