RESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Bovine babesiosis is a tick-borne disease caused by intraerythrocytic protozoa and leads to substantial economic losses for the livestock industry throughout the world. Babesia bovis is considered the most pathogenic species, which causes bovine babesiosis in Brazil. Genomic data could be used to evaluate the viability of improving resistance against B. bovis infection level (IB) through genomic selection, and, for that, knowledge of genetic parameters is needed. Furthermore, genome-wide association studies (GWAS) could be conducted to provide a better understanding of the genetic basis of the host response to B. bovis infection. No previous work in quantitative genetics of B. bovis infection was found. Thus, the objective of this study was to estimate the genetic correlation between IB and tick count (TC), evaluate predictive ability and applicability of genomic selection, and perform GWAS in Hereford and Braford cattle. The single-step genomic best linear unbiased prediction method was used, which allows the estimation of both breeding values and marker effects. Standard phenotyping was conducted for both traits. IB quantifications from the blood of 1,858 animals were carried using quantitative PCR assays. For TC, one to three subsequent tick counts were performed by manually counting adult female ticks on one side of each animal's body that was naturally exposed to ticks. Animals were genotyped using the Illumina BovineSNP50 panel. The posterior mean of IB heritability, estimated by the Bayesian animal model in a bivariate analysis, was low (0.10), and the estimations of genetic correlation between IB and TC were also low (0.15). The cross-validation genomic prediction accuracy for IB ranged from 0.18 to 0.35 and from 0.29 to 0.32 using k-means and random clustering, respectively, suggesting that genomic predictions could be used as a tool to improve genetics for IB, especially if a larger training population is developed. The top 10 single nucleotide polymorphisms from the GWAS explained 5.04% of total genetic variance for IB, which were located on chromosomes 1, 2, 5, 6, 12, 17, 18, 16, 24, and 26. Some candidate genes participate in immunity system pathways indicating that those genes are involved in resistance to B. bovis in cattle. Although the genetic correlation between IB and TC was weak, some candidate genes for IB were also reported in tick infestation studies, and they were also involved in biological resistance processes. This study contributes to improving genetic knowledge regarding infection by B. bovis in cattle.
Assuntos
Vetores Artrópodes , Babesia bovis/patogenicidade , Babesiose/genética , Babesiose/parasitologia , Bovinos/parasitologia , Genômica , Polimorfismo de Nucleotídeo Único , Carrapatos/parasitologia , Animais , Babesia bovis/genética , Babesiose/diagnóstico , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Hereditariedade , Carga Parasitária , Fenótipo , Característica Quantitativa Herdável , Índice de Gravidade de DoençaRESUMO
Foi investigado o efeito da suplementação nutricional com zeólita estilbita, sobre o consumo de alimentos de 48 ovinos da raça Santa Inês em confinamento. Os animais foram distribuídos em quatro tratamentos com níveis crescentes de zeólita de 0 (controle), 25, 50 e 75 g/animal/dia. Os alimentos fornecidos e as sobras foram pesados diariamente e semanalmente amostrados para análises laboratoriais. O consumo médio diário de matéria seca (CMS), proteína bruta (CPB) e fibra em detergente neutro (CFDN) não diferiu (P>0,05) entre os tratamentos, respectivamente 0,90, 0,140 e 0,250 kg/dia. A conversão alimentar foi (p 0,05) mais eficiente nos animais que receberam os maiores níveis de zeólita na dieta. Houve interação entre tratamento e sexo, sendo os machos superiores às fêmeas para consumo total de matéria seca. A suplementação de ovinos com zeólita nas doses testadas neste experimento, não influenciou o consumo de alimentos.(AU)
The effect of nutritional supplementation with zeolite on nutrient consumption of 48 Santa Ines confined lambs. The animals were divided into four groups of treatments with increasing levels of zeolite of 0 (control), 25, 50 and 75 g/animal/day. The food provided and the leftovers were weighed daily and weekly sampled for laboratory analysis. The average daily dry matter intake (DMI), crude protein (CP) and neutral detergent fiber (NDF) did not differ (p> .05) among the treatments, respectively 0.90, 0.140 and 0.250 kg / day. Feed conversion was (p<0.05) more efficient with the highest levels of zeolite in the diet. There was an interaction between treatment and sex, being higher than females for the total dry matter intake. Supplementation of lambs with zeolite doses tested in this experiment did not influence nutrients intake.(AU)
Se investigó el efecto de la suplementación nutricional zeolita estilbita, en el consumo de 48 ovejas de alimentos feedlot Santa Ines. Los animales se distribuyeron en cuatro tratamientos con niveles crecientes de zeolita 0 (control), 25, 50 y 75 g / animal / día. El alimento proporcionado y las sobras se pesaron diariamente y se tomaron muestras para pruebas de laboratorio semanal. La ingesta media diaria de materia seca (DMI), proteína cruda (PC) y fibra detergente neutro (FDN) no difirió (P> 0,05) entre los tratamientos, respectivamente, 0.90, 0.140 y 0.250 kg / día. La conversión de la alimentación fue (p <0.05) más eficaz en los animales que recibieron el mayor nivel de zeolita en la dieta. Hubo una interacción entre el tratamiento y el sexo, siendo los machos mayores que las hembras a la ingesta de materia seca total. La suplementación de ovejas con zeolita en las dosis ensayadas en este experimento no influyó en el consumo de alimentos.(AU)
Assuntos
Animais , Ovinos , Suplementos Nutricionais/análise , Zeolitas , Minerais na Dieta , Ingestão de AlimentosRESUMO
Foi investigado o efeito da suplementação nutricional com zeólita estilbita, sobre o consumo de alimentos de 48 ovinos da raça Santa Inês em confinamento. Os animais foram distribuídos em quatro tratamentos com níveis crescentes de zeólita de 0 (controle), 25, 50 e 75 g/animal/dia. Os alimentos fornecidos e as sobras foram pesados diariamente e semanalmente amostrados para análises laboratoriais. O consumo médio diário de matéria seca (CMS), proteína bruta (CPB) e fibra em detergente neutro (CFDN) não diferiu (P>0,05) entre os tratamentos, respectivamente 0,90, 0,140 e 0,250 kg/dia. A conversão alimentar foi (p 0,05) mais eficiente nos animais que receberam os maiores níveis de zeólita na dieta. Houve interação entre tratamento e sexo, sendo os machos superiores às fêmeas para consumo total de matéria seca. A suplementação de ovinos com zeólita nas doses testadas neste experimento, não influenciou o consumo de alimentos.
The effect of nutritional supplementation with zeolite on nutrient consumption of 48 Santa Ines confined lambs. The animals were divided into four groups of treatments with increasing levels of zeolite of 0 (control), 25, 50 and 75 g/animal/day. The food provided and the leftovers were weighed daily and weekly sampled for laboratory analysis. The average daily dry matter intake (DMI), crude protein (CP) and neutral detergent fiber (NDF) did not differ (p> .05) among the treatments, respectively 0.90, 0.140 and 0.250 kg / day. Feed conversion was (p<0.05) more efficient with the highest levels of zeolite in the diet. There was an interaction between treatment and sex, being higher than females for the total dry matter intake. Supplementation of lambs with zeolite doses tested in this experiment did not influence nutrients intake.
Se investigó el efecto de la suplementación nutricional zeolita estilbita, en el consumo de 48 ovejas de alimentos feedlot Santa Ines. Los animales se distribuyeron en cuatro tratamientos con niveles crecientes de zeolita 0 (control), 25, 50 y 75 g / animal / día. El alimento proporcionado y las sobras se pesaron diariamente y se tomaron muestras para pruebas de laboratorio semanal. La ingesta media diaria de materia seca (DMI), proteína cruda (PC) y fibra detergente neutro (FDN) no difirió (P> 0,05) entre los tratamientos, respectivamente, 0.90, 0.140 y 0.250 kg / día. La conversión de la alimentación fue (p <0.05) más eficaz en los animales que recibieron el mayor nivel de zeolita en la dieta. Hubo una interacción entre el tratamiento y el sexo, siendo los machos mayores que las hembras a la ingesta de materia seca total. La suplementación de ovejas con zeolita en las dosis ensayadas en este experimento no influyó en el consumo de alimentos.
Assuntos
Animais , Minerais na Dieta , Ovinos , Suplementos Nutricionais/análise , Zeolitas , Ingestão de AlimentosRESUMO
Herbal extracts have been investigated as an alternative for parasite control, aiming to slow the development of resistance and to obtain low-cost biodegradable parasiticides. The goal of this study was to evaluate the efficacy, in vitro, of 11 essential oils from Brazil on reproductive efficiency and lethality of the cattle tick Rhipicephalus (Boophilus) microplus. The effects of oils extracted from Curcuma longa, Zingiber officinale, Lippia alba, Lippia gracilis, Lippia origanoides, Lippia sidoides, Mentha arvensis, Mentha piperita, Croton cajucara (white and red), and Croton sacaquinha on ticks were investigated by the Immersion Test with Engorged Females (ITEF) and the modified Larval Packet Test (LPT). Distilled water and 2% Tween 80 were used as control treatments. Chemical analysis of the oils was done with gas chromatography coupled with mass spectrometry. Analysis of the in vitro tests using Probit (SAS program) allowed the calculation of lethal concentrations (LCs). Lower reproductive efficiency indexes and higher efficacy percentages in the ITEF were obtained with the oils extracted from C. longa (24 and 71%, respectively) and M. arvensis oils (27 and 73%, respectively). Lower LC50 was reached with C. longa (10.24 mg/mL), L. alba (10.78 mg/mL), M. arvensis (22.31 mg/mL), L. sidoides (27.67 mg/mL), and C. sacaquinha (29.88 mg/mL) oils. In the LPT, species from Zingiberaceae and Verbenaceae families caused 100% lethality at 25 mg/mL, except for L. sidoides. The most effective oils were from C. longa, L. gracilis, L. origanoides, L. alba, and Z. officinale. The LC50 and LC90 were, respectively: 0.54 and 1.80 mg/mL, 3.21 and 7.03 mg/mL, 3.10 and 8.44 mg/mL, 5.85 and 11.14 mg/mL, and 7.75 and 13.62 mg/mL. The efficacy was directly related to the major components in each essential oil, and the oils derived from Croton genus presented the worst performance, suggesting the absence of synergistic effect among its compounds. Since C. longa, containing 62% turmerone, was the one most efficient against ticks, this compound may be potentially used for tick control, but further research is needed, especially to assess toxicity of these compounds to the host. These new studies, together with the results presented here, may provide a strong rationale for designing pre-clinical and clinical studies with these agents.
Assuntos
Acaricidas/farmacologia , Curcuma/química , Lippia/química , Óleos Voláteis/farmacologia , Óleos de Plantas/farmacologia , Rhipicephalus/efeitos dos fármacos , Zingiber officinale/química , Acaricidas/isolamento & purificação , Animais , Brasil , Bovinos , Relação Dose-Resposta a Droga , Feminino , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Óleos Voláteis/isolamento & purificação , Óleos de Plantas/isolamento & purificação , Plantas Medicinais , Rhipicephalus/crescimento & desenvolvimento , Taxa de Sobrevida , Controle de Ácaros e Carrapatos/métodos , Infestações por Carrapato/parasitologia , Infestações por Carrapato/veterináriaRESUMO
Measures to control the cattle tick, Rhipicephalus (Boophilus) microplus, based only on chemical products are becoming unsustainable, mainly because of the development of resistance. The objective of this study was to test the effect of the aqueous extract of pineapple skin (AEPS) and bromelain extracted from the stem (Sigma-Aldrich®, B4882) on engorged females and larvae of R. (B.) microplus in vitro. These substances were diluted in water and evaluated at eight concentrations. Engorged females were collected and distributed in groups of 10, with three repetitions for each treatment. After immersion in the solutions, the females were placed in an incubator for observation of survival, oviposition and larval hatching. The larval packet method was used, also with three repetitions with about 100 larvae each. The packets were incubated and the readings were performed after 24 h. The estimated reproduction and efficacy of the solutions were calculated. The LC(50) and LC(90) were estimated using the Probit procedure of the SAS program. The eight concentrations were compared within each treatment by the Tukey test. For the experiment with engorged females, the most effective concentrations were 125, 250 and 500 mg/mL: 33%, 48% and 59% for the AEPS and 27%, 51% and 55% for the bromelain. The LC(50) and LC(90) values were, respectively, 276 and 8691 mg/mL for AEPS and 373 and 5172 mg/mL for bromelain. None of the dilutions tested was effective against the larvae of R. (B.) microplus. This is the first report of the action of pineapple extracts or their constituents on cattle ticks. The results demonstrate that further studies regarding composition of tick cuticle, with evaluation of other solvents and formulations, should be conducted seeking to enhance the effect of pineapple extracts and compounds against this ectoparasite.
Assuntos
Ananas/química , Doenças dos Bovinos/prevenção & controle , Extratos Vegetais , Rhipicephalus , Controle de Ácaros e Carrapatos/métodos , Infestações por Carrapato/veterinária , Animais , Bromelaínas/isolamento & purificação , Bovinos , Doenças dos Bovinos/parasitologia , Feminino , Frutas/química , Larva , Dose Letal Mediana , Extratos Vegetais/isolamento & purificação , Infestações por Carrapato/parasitologia , Infestações por Carrapato/prevenção & controleRESUMO
The activity of plant extracts on parasites may indicate groups of substances that are potentially useful for controlling Rhipicephalus (Boophilus) microplus. The aim of the present study was to investigate the in vitro action of Artemisia annua extracts on this tick. The concentrations of the sesquiterpene lactones artemisinin and deoxyartemisinin present in plant extracts were quantified via high-performance liquid chromatography. Four extracts produced from the concentrated crude extract (CCE) were evaluated on larvae using the impregnated paper method, with readings after 24 hours of incubation. The engorged females were immersed in the CCE and in its four derived extracts for five minutes, with incubation for subsequent analysis of biological parameters. The extracts were not effective on the larvae at the concentrations tested (3.1 to 50 mg.mL(-1)). The CCE showed greater efficacy on engorged females (EC(50) of 130.6 mg.mL(-1) and EC(90) of 302.9 mg.mL(-1)) than did the derived extracts. These results tend to confirm that the action of artemisinin on engorged females of R. (B.) microplus is conditional to their blood intake. In this case, in vitro methods would be inadequate for effective evaluation of the action of A. annua on R. (B.) microplus.
Assuntos
Artemisia annua , Extratos Vegetais/farmacologia , Rhipicephalus/efeitos dos fármacos , Controle de Ácaros e Carrapatos , AnimaisRESUMO
The activity of plant extracts on parasites may indicate groups of substances that are potentially useful for controlling Rhipicephalus (Boophilus) microplus. The aim of the present study was to investigate the in vitro action of Artemisia annua extracts on this tick. The concentrations of the sesquiterpene lactones artemisinin and deoxyartemisinin present in plant extracts were quantified via high-performance liquid chromatography. Four extracts produced from the concentrated crude extract (CCE) were evaluated on larvae using the impregnated paper method, with readings after 24 hours of incubation. The engorged females were immersed in the CCE and in its four derived extracts for five minutes, with incubation for subsequent analysis of biological parameters. The extracts were not effective on the larvae at the concentrations tested (3.1 to 50 mg.mL-1). The CCE showed greater efficacy on engorged females (EC50 of 130.6 mg.mL-1 and EC90 of 302.9 mg.mL-1) than did the derived extracts. These results tend to confirm that the action of artemisinin on engorged females of R.(B.) microplus is conditional to their blood intake. In this case, in vitro methods would be inadequate for effective evaluation of the action of A. annua on R. (B.) microplus.
A atividade de extratos vegetais sobre parasitas pode indicar grupos de substâncias de uso potencial no controle de Rhipicephalus (Boophilus) microplus. O objetivo do presente estudo foi investigar a ação in vitro de extratos de Artemisia annua sobre esta espécie. A concentração das lactonas sesquiterpênicas artemisinina e deoxiartemisinina presentes nos extratos vegetais, foi quantificada via cromatografia líquida de alta eficiência. Quatro extratos produzidos a partir do extrato bruto concentrado (EBC) foram avaliados sobre larvas pela metodologia do papel impregnado, com leitura após 24 horas de incubação. As fêmeas ingurgitadas foram imersas por cinco minutos no EBC e nos seus quatro extratos derivados, e incubadas para posterior análise dos parâmetros biológicos. Os extratos não tiveram eficácia sobre as larvas nas concentrações avaliadas (de 3,1 a 50 mg.mL-1). O EBC apresentou melhor eficácia sobre as fêmeas ingurgitadas (CE 50 de 130,6 mg.mL-1 e CE 90 de 302,9 mg.mL-1) que os extratos derivados. Esses resultados tendem a confirmar que a ação da artemisinina sobre as fêmeas ingurgitadas de R. (B.) microplus estaria condicionada à sua ingestão através do sangue. Nesse caso, os métodos in vitro seriam inadequados para a efetiva avaliação da ação de A. annua R.(B.) microplus.
Assuntos
Animais , Artemisia annua , Extratos Vegetais/farmacologia , Rhipicephalus/efeitos dos fármacos , Controle de Ácaros e CarrapatosRESUMO
Much attention has been given to the development of botanical insecticides to provide effective natural control of cattle ectoparasites without harming animals, consumers, and environment. This study evaluated the efficacy of a commercial neem cake in controlling Haematobia irritans infestation on cattle. The study was conducted at the Embrapa Southeast Cattle Research Center (CPPSE), in São Carlos, SP, Brazil, from April to July 2008. The neem cake mixed in mineral salt in a 2% concentration was provided to 20 Nelore cows during nine weeks and had its efficacy evaluated by comparison of the infestation level against a control group. Fly infestations were recorded weekly by digital photographs of each animal from both groups and the number of flies was later counted in a computer-assisted image analyzer. Quantification of neem cake components by high-performance liquid chromatography revealed the presence of azadirachtin (421 mg.kg(-1)) and 3-tigloyl-azadirachtol (151 mg.kg(-1)) in the tested neem cake. Addition of the 2% neem cake reduced mineral salt intake in about 22%. The 2% neem cake treatment failed to reduce horn fly infestations on cattle during the 9-week study period.
Assuntos
Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/parasitologia , Ectoparasitoses/veterinária , Glicerídeos , Controle de Insetos , Repelentes de Insetos , Muscidae , Terpenos , Animais , Bovinos , Ectoparasitoses/prevenção & controleRESUMO
Much attention has been given to the development of botanical insecticides to provide effective natural control of cattle ectoparasites without harming animals, consumers, and environment. This study evaluated the efficacy of a commercial neem cake in controlling Haematobia irritans infestation on cattle. The study was conducted at the Embrapa Southeast Cattle Research Center (CPPSE), in São Carlos, SP, Brazil, from April to July 2008. The neem cake mixed in mineral salt in a 2 percent concentration was provided to 20 Nelore cows during nine weeks and had its efficacy evaluated by comparison of the infestation level against a control group. Fly infestations were recorded weekly by digital photographs of each animal from both groups and the number of flies was later counted in a computer-assisted image analyzer. Quantification of neem cake components by high-performance liquid chromatography revealed the presence of azadirachtin (421 mg.kg-1) and 3-tigloyl-azadirachtol (151 mg.kg-1) in the tested neem cake. Addition of the 2 percent neem cake reduced mineral salt intake in about 22 percent. The 2 percent neem cake treatment failed to reduce horn fly infestations on cattle during the 9-week study period.
Muita atenção tem sido dada ao desenvolvimento de inseticidas vegetais buscando-se um efetivo controle de ectoparasitas de bovinos, sem prejudicar animais, consumidores e meio ambiente. Este estudo, realizado de abril a julho de 2008, na Embrapa Pecuária Sudeste, em São Carlos, SP, Brasil, avaliou a eficácia de uma torta comercial de nim (Azadirachta indica) no controle da mosca-dos-chifres (Haematobia irritans) em bovinos. A torta de nim, misturada ao sal mineral na concentração de 2 por cento, foi fornecida a 20 vacas Nelore, durante nove semanas, e sua eficácia foi monitorada através de contagens semanais nos grupos tratado e controle. Infestações individuais foram registradas por meio de fotos digitais em todos os animais de ambos os grupos, e o número de moscas foi, posteriormente, quantificado com o auxílio de um sistema de análise de imagem computadorizado. A quantificação dos componentes da torta de nim, por cromatografia líquida, revelou a presença de azadiractina (421 mg.kg-1) e 3-tigloyl-azadirachtol (151 mg.kg-1). A adição da torta de nim a 2 por cento reduziu o consumo de sal mineral em cerca de 22 por cento. O tratamento com torta de nim a 2 por cento não reduziu as infestações por mosca-dos-chifres em bovinos durante as nove semanas do estudo.
Assuntos
Animais , Bovinos , Doenças dos Bovinos/parasitologia , Doenças dos Bovinos/prevenção & controle , Ectoparasitoses/veterinária , Glicerídeos , Controle de Insetos , Repelentes de Insetos , Muscidae , Terpenos , Ectoparasitoses/prevenção & controleRESUMO
The present study provides the first epidemiological data regarding infection by Anaplasma marginale in cattle reared in south-western Brazilian Amazonia. One simple procedure was adapted for the extraction of DNA from blood clots collected in seven microregions of Rondônia State and two mesoregions of Acre State. PCR method was used to asses the frequency of A. marginale infections in 4 to12-month-old cattle. The cattle infection was investigated by polymerase chain reaction (PCR) using the specific primer "msp5" for A. marginale. The DNA amplifications revealed that the mean frequency of A. marginale infection was 98.6 percent (1,627/1,650) in samples from Rondonia, and 92.87 percent (208/225) in samples from Acre. The high frequency of A. marginale infections in 4 to 12-month-old cattle indicate a situation of enzootic stability in the studied areas and are comparable to those detected by immunodiagnosis in different endemic regions in Brazil. The DNA extraction of clotted blood method described here can be used for epidemiological studies on anaplasmosis and other bovine hemoparasites.
O presente estudo fornece os primeiros dados epidemiológicos relativos a infecção por Anaplasma marginale em bovinos criados na Amazônia Sul Ocidental brasileira. Foi adaptado um procedimento simples para a extração de DNA a partir de coágulos sanguíneos coletados em sete microrregiões do estado de Rondônia e duas mesoregiões do estado do Acre. A técnica da reação em cadeia da polimerase (PCR) foi aplicada para avaliar a freqüência da infecção por A. marginale em bovinos com idade entre 4 e 12 meses. Após a extração do DNA de cada amostra, a infecção nos bovinos foi investigada pela amplificação do gene "msp5" de A. marginale. As técnicas de amplificação do DNA revelaram que a freqüência de infecção por A. marginale foi de 98,6 por cento (1.627/1.650) nas amostras provenientes de Rondônia e de 92,87 por cento (208/225) nas amostras do Acre. A alta freqüência da infecção por A. marginale nos animais com idade entre 4 e 12 meses indica uma situação de estabilidade enzoótica nas regiões estudadas, as quais são comparáveis às detectadas por técnicas de imunodiagnóstico em outras regiões endêmicas no Brasil. A extração do DNA através do método aqui descrito pode ser utilizado em estudos epidemiológicos sobre a anaplasmose bovina e outros hemoparasitas.
Assuntos
Animais , Bovinos , Anaplasma marginale/genética , Anaplasma marginale/isolamento & purificação , Infecções Bacterianas/reabilitação , Infecções Bacterianas/sangue , Infecções Bacterianas/transmissão , Infecções Bacterianas/veterinária , Epidemiologia/estatística & dados numéricos , Parasitos/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Reação em Cadeia da Polimerase/veterináriaRESUMO
The present study provides the first epidemiological data regarding infection by Anaplasma marginale in cattle reared in south-western Brazilian Amazonia. One simple procedure was adapted for the extraction of DNA from blood clots collected in seven microregions of Rondônia State and two mesoregions of Acre State. PCR method was used to asses the frequency of A. marginale infections in 4 to12-month-old cattle. The cattle infection was investigated by polymerase chain reaction (PCR) using the specific primer "msp5" for A. marginale. The DNA amplifications revealed that the mean frequency of A. marginale infection was 98.6 percent (1,627/1,650) in samples from Rondonia, and 92.87 percent (208/225) in samples from Acre. The high frequency of A. marginale infections in 4 to 12-month-old cattle indicate a situation of enzootic stability in the studied areas and are comparable to those detected by immunodiagnosis in different endemic regions in Brazil. The DNA extraction of clotted blood method described here can be used for epidemiological studies on anaplasmosis and other bovine hemoparasites.(AU)
O presente estudo fornece os primeiros dados epidemiológicos relativos a infecção por Anaplasma marginale em bovinos criados na Amazônia Sul Ocidental brasileira. Foi adaptado um procedimento simples para a extração de DNA a partir de coágulos sanguíneos coletados em sete microrregiões do estado de Rondônia e duas mesoregiões do estado do Acre. A técnica da reação em cadeia da polimerase (PCR) foi aplicada para avaliar a freqüência da infecção por A. marginale em bovinos com idade entre 4 e 12 meses. Após a extração do DNA de cada amostra, a infecção nos bovinos foi investigada pela amplificação do gene "msp5" de A. marginale. As técnicas de amplificação do DNA revelaram que a freqüência de infecção por A. marginale foi de 98,6 por cento (1.627/1.650) nas amostras provenientes de Rondônia e de 92,87 por cento (208/225) nas amostras do Acre. A alta freqüência da infecção por A. marginale nos animais com idade entre 4 e 12 meses indica uma situação de estabilidade enzoótica nas regiões estudadas, as quais são comparáveis às detectadas por técnicas de imunodiagnóstico em outras regiões endêmicas no Brasil. A extração do DNA através do método aqui descrito pode ser utilizado em estudos epidemiológicos sobre a anaplasmose bovina e outros hemoparasitas.(AU)
Assuntos
Animais , Bovinos , Anaplasma marginale/genética , Anaplasma marginale/isolamento & purificação , Infecções Bacterianas/sangue , Infecções Bacterianas/reabilitação , Infecções Bacterianas/transmissão , Infecções Bacterianas/veterinária , Parasitos/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Reação em Cadeia da Polimerase/veterinária , Epidemiologia/estatística & dados numéricosRESUMO
Resistance of beef cattle heifers to the cattle tick Boophilus microplus was evaluated by artificial infestation of 66 beef cattle heifers of the following genetic groups: 16 Nelore (NE), 18 Canchim x Nelore (CN), 16 Angus x Nelore (AN) and 16 Simmental x Nelore (SN). The animals, with a mean age of 16.5 months, were maintained with no chemical tick control in a Brachiaria decumbens pasture. Four artificial infestations with 20,000 B. microplus larvae were carried out 14 days apart and from day 18 to day 22 of each infestation the number of engorged female ticks (> 4.5 mm) was counted on the left side of each heifer. Data were analyzed as the percentage of return (PR = percentage of ticks counted relative to the number infested), transformed to (PR)», and as log10 (Cij + 1), in which Cij is the number of ticks in each infestation, using the least squares method with a model that included the effects of genetic group (GG), animal within GG (error a), infestation number (I), GG x I and the residual (error b). Results indicated a significant GG x I interaction, because AN and SN heifers had a higher percentage of return than CN and NE heifers, while CN heifers showed a higher percentage of return than the NE heifers only in infestations 3 and 4. Transformed percentages of return were NE = 0.35 ± 0.06, AN = 0.89 ± 0.06, CN = 0.54 ± 0.05 and SN = 0.85 ± 0.06.