Resistance of Santa Ines and crossbred ewes to naturally acquired gastrointestinal nematode infections

This trial was carried out in Piracicaba, Sao Paulo State. Brazil. to comparatively evaluate the degree of resistance to naturally acquired gastrointestinal nematode infections in sheep of the following genetic groups purebred Santa Ines (SI), SI crossbred with Dorper (DO x SI), lie de France (IF x SI), Suffolk (SU x SI), and Texel (TE < SI) Fifteen ewes from each group were raised indoors until 12 months of age. At this age, they were moved to pasture that was naturally contaminated by nematode infective larvae and were evaluated from December to May. 2007. Rainfall ranged from 267 mm in January to 37 mm in April Maximum and minimum mean temperatures ranged from 32 5 degrees C to 19 0 degrees C in March and from 25.9 degrees C to 12.8 degrees C in May. There was an increase in the mean number of eggs per gram of feces (EPG) after animals were placed on pasture with significant difference between the SI (80 EPG) and IF x SI (347 EPG) groups in January: and the DO x SI (386 EPG) and TE x SI (258 EPG) groups in May. The highest mean fecal egg count (FEC), 2073 EPG, was recorded for the TE x SI group in February. All groups showed a progressive reduction in body weight throughout the experiment of 12.0% (TE x SI) to 15.9% (SU x SI). In general. the animals with the highest FEC presented the lowest packed cell volumes (PCV): the highest correlation coefficient between FEC x PCV occurred in the SU x SI sheep in January (r = -0.70; P < 0.01). Similarly, there was an inverse relationship between FEC and blood eosinophil Values, with the highest correlation coefficient in the TE x SI sheep in February (r = -0.64; P < 0.05). Immunoglobulin G (IgG) levels against Haemonchus contortus antigens increased in all groups as a result of the exposure to parasites and remained relatively constant until the end of the study, with the exceptions of SU x SI and TE x SI, which showed a rise in IgG levels during the last sampling that coincided with a reduction in mean FEC. In conclusion. crossbreeding Santa Ines sheep with any of the breeds evaluated can result in a production increase and the maintenance of a satisfactory degree of infection resistance, especially against H. contortus and Trichostrongylus colubriformis. the major nematodes detected in this flock. (c) 2009 Elsevier B.V. All rights reserved.

Controle de nematóides parasitos gastrintestinais por Arthrobotrys musiformis em ovinos naturalmente infestados mantidos em pastagens

Este trabalho objetivou avaliar, in vitro e in vivo, o fungo predador Arthrobotrys musiformis, administrado via oral na forma de conídios microencapsulados em alginato ou in natura em meio líquido, após passagem pelo trato gastrintestinal de ovinos. No teste in vitro, avaliou-se a manutenção da atividade predatória, e no teste in vivo, a capacidade de controlar nematóides parasitos de ovinos naturalmente infectados, mantidos em pastagens. O resultado do teste in vitro confirmou a viabilidade de A. musiformis (95,5%), mesmo após a passagem pelo trato gastrintestinal. Na avaliação in vivo, não houve diferença estatística entre o número de ovos por grama de fezes dos grupos tratados e controle, provavelmente em razão da baixa lotação dos piquetes, da quantidade e periodicidade insuficientes de oferecimento de conídios aos ovinos, o que teria proporcionado dispersão e migração das larvas na pastagem. Contudo, os helmintos recuperados na necropsia dos animais traçadores mostraram que A. musiformis reduziu em 50,9% e 57,6% o número de Trichostrongylus colubriformis dos grupos tratados com conídios microencapsulados e in natura, respectivamente, e em 95% o número de L4 de Haemonchus do grupo tratado com conídios in natura. Embora os resultados não sejam conclusivos, A. musiformis mostrou-se promissor agente no biocontrole de nematóides parasitos gastrintestinais.

Eficácia anti-helmíntica comparativa da associação albendazole, levamisole e ivermectina à moxidectina em ovinos

Avaliou-se a eficácia anti-helmíntica da associação de albendazole 2,0%, cloridrato de levamisole 2,55% e ivermectina 0,08% comparativamente à moxidectina 1% em ovinos naturalmente infectados. Foram selecionados 24 ovinos para a composição de três grupos experimentais com oito animais cada: T1, ovinos tratados com a associação albendazole, levamisole e ivermectina, na dosagem de 1 mL 4 kg-1 de peso corporal; T2, ovinos tratados com moxidectina, na dosagem de 1 mL 50 kg-1 de peso corporal e T3, ovinos sem tratamento anti-helmíntico. Foram realizadas contagens de ovos por grama de fezes (OPG) no primeiro, terceiro, quinto e sétimo dia após os tratamentos. No sétimo dia todos os ovinos foram necropsiados e todos os helmintos encontrados no trato gastrintestinal foram quantificados e identificados quanto ao gênero e à espécie. A associação dos diferentes princípios ativos foi 100% eficaz no combate às espécies Cooperia punctata, C. pectinata, C. spatulata, Trichostrongylus axei, Oesophagostomum columbianum, Trichuris ovis, C. curticei e Strongyloides papillosus e, a moxidectina eliminou as seis primeiras espécies citadas. Contra Haemonchus contortus a associação apresentou eficácia superior (93%) à moxidectina (51,4%). Ambas formulações foram eficazes contra Trichostrongylus colubriformis. A associação medicamentosa utilizada constitui alternativa no controle das nematodioses ovinas.

Resistência anti-helmíntica de nematóides gastrintestinais em ovinos, Mato Grosso do Sul

Entre os métodos de controle da verminose gastrintestinal em ovinos, a utilização de produtos químicos é o mais empregado. Porém, o uso indiscriminado e continuado desses produtos tem selecionado populações de helmintos resistentes aos anti-helmínticos, fenômeno relatado no mundo todo. Este trabalho teve como objetivo identificar as espécies de parasitos gastrintestinais e diagnosticar a situação da resistência anti-helmíntica em ovinos no Estado de Mato Grosso do Sul. Foram realizados testes de redução na contagem de ovos por grama de fezes (OPG) em rebanhos de dezesseis propriedades rurais; as sete formulações utilizadas continham as seguintes bases farmacológicas: Albendazol, Ivermectina, Levamisole, Triclorfon, Moxidectina, Closantel e uma contendo as três primeiras associadas. As espécies identificadas nas necropsias, em ovinos adultos, foram: Haemonchus contortus, Trichostrongylus colubriformis, Cooperia curticei, C. punctata, C. pectinata e Oesophagostomum columbianum; em ordem de prevalência. As formulações contendo Albendazol e Ivermectina não apresentaram eficácia na redução de OPG nos rebanhos testados, com médias de redução de 0,7 e -19,6%, respectivamente. Closantel apresentou eficácia média de 6,7%; Levamisole, Moxidectina e Triclorfon de 28,7, 26,8 e 65%, respectivamente; a associação das três bases (Albendazol, Ivermectina e Levamisole), uma média de eficácia de 55,8%. As percentagens médias de larvas infectantes recuperadas nas coproculturas, tanto no pré como no pós-tratamento, foram semelhantes; indicando que a resistência às bases testadas está presente em todas as espécies citadas, em maior ou menor intensidade. Os dois gêneros predominantemente resistentes são Haemonchus sp., com 86,9%; seguido por Trichostrongylus sp., com média de 47,5%; Strongyloides sp. 33,6%; Oesophagostomum, sp. 21,4% e Cooperia sp. 19,7%.

Effect of fall-grazed sericea lespedeza (Lespedeza cuneata) on gastrointestinal nematode infections of growing goats

High prevalence of anthelmintic-resistant gastrointestinal nematodes (GIN) in goats has increased pressure to find effective, alternative non-synthetic control methods, one of which is adding forage of the high condensed tannin (CT) legume sericea lespedeza (SL; Lespedeza cuneata) to the animal's diet. Previous work has demonstrated good efficacy of dried SL (hay, pellets) against small ruminant GIN, but information is lacking on consumption of fresh SL, particularly during the late summer–autumn period in the southern USA when perennial warm-season grass pastures are often low in quality. A study was designed to determine the effects of autumn (September–November) consumption of fresh SL forage, grass pasture (predominantly bermudagrass, BG; Cynodon dactylon), or a combination of SL + BG forage by young goats [intact male Spanish kids, 9 months old (20.7 ± 1.1 kg), n = 10/treatment group] on their GIN infection status. Three forage paddocks (0.40 ha) were set up at the Fort Valley State University Agricultural Research Station (Fort Valley, GA) for an 8-week trial. The goats in each paddock were supplemented with a commercial feed pellet at 0.45 kg/head/d for the first 4 weeks of the trial, and 0.27 kg/head/d for the final 4 weeks. Forage samples taken at the start of the trial were analyzed for crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) content, and a separate set of SL samples was analyzed for CT in leaves, stems, and whole plant using the benzyl mercaptan thiolysis method. Animal weights were taken at the start and end of the trial, and fecal and blood samples were collected weekly for determination of fecal egg counts (FEC) and packed cell volume (PCV), respectively. Adult GIN was recovered from the abomasum and small intestines of all goats at the end of the experiment for counting and speciation. The CP levels were highest for SL forage, intermediate for SL + BG, and lowest for BG forage samples, while NDF and ADF values were the opposite, with highest levels in BG and lowest in SL forage samples. Sericea lespedeza leaves had more CT than stems (16.0 g vs. 3.3 g/100 g dry weight), a slightly higher percentage of PDs (98% vs. 94%, respectively) and polymers of larger mean degrees of polymerization (42 vs. 18, respectively). There were no differences in average daily gain or blood PCV between the treatment groups, but SL goats had lower FEC (P < 0.05) than the BG or SL + BG forage goats throughout most of the trial. The SL + BG goats had lower FEC than the BG forage animals by the end of the trial (week 8, P < 0.05). The SL goats had lower numbers (P < 0.05) of male Haemonchus contortus and tended to have fewer female (P < 0.10) and total (P < 0.07) H. contortus compared with the BG goats. The predominant GIN in all the goats was Trichostrongylus colubriformis (73% of total GIN). As a low-input forage with activity against pathogenic GIN (H. contortus), SL has a potential to reduce producers’ dependence upon synthetic anthelmintics and also to fill the autumn ‘window’ in good-quality fresh forages for goat grazing in the southern USA.

Helminth fauna of bovines from the Central-Western region, Minas Gerais State, Brazil

A prevalência e a intensidade de parasitismo por diferentes espécies de helmintos foram estudadas em bovinos da microrregião de Formiga, região Centro-oeste de Minas Gerais. Para tanto, foram necropsiados 76 bovinos naturalmente infectados, machos e fêmeas, SRD (sem raça definida) e de oito a 12 meses de idade. Os resultados necroscópicos revelaram a presença de nove gêneros e 16 espécies de helmintos, com a seguinte prevalência e média de intensidade de infecção: Haemonchus placei (100,0%; 3895,5); Haemonchus similis (29,0%; 159,6); Cooperia punctata (100,0%; 5595,0); Cooperia spatulata (32,9%; 137,8); Cooperia pectinata (34,2%; 1010,5); Trichostrongylus axei (69,7%; 239,2); Trichostrongylus colubriformis (10,5%; 10,8); Trichostrongylus longyspicularis (2,6%; 0,5); Ostertagia ostertagi (2,6%; 3,1); Ostertagia lyrata (2,6%; 1,5); Ostertagia trifurcata (1,3%; 0,3); Oesophagostomum radiatum (94,7%; 470,9); Trichuris discolor (47,4%; 32,5); Strongyloides papillosus (1,3%; 0,1); Capillaria bovis (9,2%; 10) e Bunostomum phlebotomum (2,6%; 0,3). A carga parasitária média foi de 11.558,5 helmintos por animal. Dos 76 bovinos necropsiados, 92,1% estavam infectados por três a sete espécies de helmintos. Apenas 7,9% dos hospedeiros mostravam-se parasitados por oito espécies diferentes de helmintos. Este estudo mostra o primeiro relato das espécies Ostertagia lyrata e Ostertagia trifurcata no Estado de Minas Gerais. É importante ressaltar que, no presente trabalho, por meio da identificação dos helmintos colhidos nas necropsias, foi possível observar que está ocorrendo uma inversão na intensidade parasitária média, com uma diminuição no número de Cooperia e um aumento nos valores de Haemonchus, em comparação com os valores relatados na literatura.

Controle de nematóides parasitos gastrintestinais por Arthrobotrys musiformis em ovinos naturalmente infestados mantidos em pastagens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Eficácia anti-helmíntica comparativa da associação albendazole, levamisole e ivermectina à moxidectina em ovinos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Resistance of Santa Ines, Suffolk and Ile de France sheep to naturally acquired gastrointestinal nematode infections

A study was conducted to assess the breed resistance against nematode infections in Santa Ines, Ile de France and Suffolk male lambs over a 9-month period in São Paulo state, Brazil. Lambs were born during the winter (year 2000) and were weaned at 2 months of age. The animals were then housed and treated with anthelmintics to eliminate natural infections by gastrointestinal nematodes. In late October 2000, lambs were placed in a paddock, where they stayed until August of the following year. Fecal and blood samples were taken from each animal every 2 weeks. on the same day, a pasture sample was collected to determine the number of infective larvae on the herbage. To prevent deaths, individual treatment with anthelmintics was provided to lambs with fecal egg counts (FEC) higher than 4000 eggs per gram (EPG) or with a packed cell volume (PCV) lower than 21%. In August 2001, all animals were slaughtered and the worms present in samples of the gastrointestinal contents were identified and counted. Most of the Suffolk and Ile de France sheep received three to six anthelmintic treatments over a period of 7 months, while most of the Santa Ines were not treated. Reductions in PCV and plasma protein values associated with high FEC and worm burdens were recorded, particularly, in Suffolk and Ile de France lambs. Haemonchus contortus and Oesophagostomum columbianum burdens and number of nodular lesions caused in the large intestine by O. columbianum larvae were significantly lower in Santa Ines sheep. All three breeds showed similar Trichostrongylus colubriformis worm burdens. The relative resistance of Santa Ines young male sheep was superior to that of Suffolk and Ile de France sheep. (C) 2004 Elsevier B.V. All rights reserved.

Parasitism by Oestrus ovis: Influence of sheep breed and nematode infections

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Resistance of Santa Ines and crossbred ewes to naturally acquired gastrointestinal nematode infections

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Immune responses in sheep naturally infected with Oestrus ovis (Diptera: Oestridae) and gastrointestinal nematodes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sheep and cattle grazing alternately: Nematode parasitism and pasture decontamination

Three grazing management systems were compared to examine pasture decontamination of gastrointestinal nematode parasites (GIN) of sheep (Ovies aries) and cattle (Bos taurus). They consisted of sheep and cattle grazing paddocks alternately for 32, 96 or 192 days over 2 years. Pastureland (8.43 ha) was subdivided into six areas of eight paddocks each to produce an eight-paddock rotational grazing system. Every paddock was grazed for 4 days and then rested for 28 days. Sixty-six Ile de France ewes and 12 steers were randomly divided into three groups (22 sheep and four cattle per group). Each grazing system included a cattle area and a sheep area. Sheep and cattle interchanged areas every 32 days in system 1 (Group 1), every 96 days in system 2 (Group 2) and every 192 days in system 3 (Group 3). Fecal examination and larvae counting on pasture were performed every 32 days. During summer, winter and spring 2005, tracer lambs free of nematode infection were introduced into each sheep group and later sacrificed for quantification and identification of GIN species. All cattle were sacrificed for the same purpose. The main parasites found in tracer lambs were Haemonchus contortus and Trichostrongylus colubriformis, and in cattle, Haemonchus similis, Cooperia punctata and Oesophagostomum radiatum. Pasture contamination by sheep-infective GIN larvae was considerably reduced after 96 or 192 days of cattle grazing. Cross-infections between sheep and cattle GIN were not significant, which suggested that integrated grazing using such animals could be used for pasture decontamination. However, as effective anthelmintics were not available, decontamination was not sufficient for proper prophylaxis of GIN infections in Ile de France sheep, which are quite susceptible to such parasites. © 2007 Elsevier B.V. All rights reserved.

Helmintos parasitos de mocós (Kerodon rupestris Rodentia: Caviidae) de vida livre e de cativeiro, no semi-árido nordestino Brasileiro

This study shows the helminthic fauna of 16 rock cavies (Kerodon rupestris) from the semi-arid region in the State of Rio Grande do Norte, Brazil. Nine animals were captured from the wild and seven from a captive population located at the Centro de Multiplicação de Animais Silvestres, city of Mossoró, were examined in this study. The animals were slaughtered, and post mortem analysis of the digestive tract, trachea, heart, lungs, liver, pancreas, and kidneys were done in search for the presence of parasites. Five species of nematode (Paraspidodera uncinata, Trichostrongylus colubriformis, Trichuris gracilis, Trichuris muris, and Vianella lenti) and one species of cestode (Thysanotaenia congolensis) were identified.