Herd-level risk factors for Neospora caninum seroprevalence in dairy farms in southern Brazil     

Corbellini LG  Smith DR  Pescador CA  Schmitz M  Correa A  Steffen DJ  Driemeier D 《Preventive veterinary medicine》2006,74(2-3):130-141

A cross-sectional study was used to test the relationship between herd seroprevalence to Neospora caninum and various potential herd-level risk factors in 60 dairy farms located in two distinct regions in southern Brazil. Thirty farms were randomly selected from within each region. A questionnaire was designed to summarize each farm's production system as it might relate to N. caninum transmission. The questionnaire contained 105 closed questions relating to general characteristics of the farms, farm facilities, management, source of food and water, herd health, environment and biosecurity, which included questions relevant to N. caninum transmission, including presence and number of dogs and other animals, purchase of animals and contact with man. Serum samples were collected from 40% of animals in each farm and N. caninum antibodies were detected by immunofluorescent antibody test (IFAT). The association between potential risk factors and the probability of an animal being seropositive was modeled using a generalized estimation equations (GEE) logistic regression model. The model accounted for multilevel correlation of data from multiple animals within herds. The mean (+/-S.D.) number of animals in the 60 herds was 64.5 (+/-45.6), ranging from 20 to 280 females. Blood samples were collected from 1549 animals. The size of the farms varied from 4 to 100 ha (mean 30.1+/-25.9 ha). At least one dog was found in 57 of the 60 dairy farms (95%). The mean number of dogs was 3.1 (+/-1.9), ranging from 0 to 10. All females were raised on pasture. For all cattle sampled, N. caninum seroprevalence was 17.8%. Overall, 93.3% of herds (56/60) had at least one seropositive animal identified. Four variables were significantly associated with N. caninum sero-response in the 57 dairy farms, which were included in the final multivariable model: the number of dogs on the farm, farm area (hectares), feeding pooled sources of colostrum and region. The odds of a cow being seropositive increased 1.13 times for each additional dog present on the farm (P=0.021). Cattle from farms that fed calves colostrum pooled from multiple cows had 1.79 times greater odds for being seropositive for N. caninum (P<0.003). The probability of being seropositive was inverse to the area of the farms, such that cattle had 0.92 times the odds to be seropositive (P=0.014) for each additional 10 ha of farmland. Finally, cattle from farms in region one had 0.71 times the odds to be seropositive than cattle from region two (P=0.035). Results of this study suggest that several risk factors may explain why dairy cattle in Brazil may become exposed to N. caninum. However, further investigation of these factors is necessary because the purpose of this study was to refine and generate hypotheses on N. caninum transmission.  相似文献   

Experiments on anthelmintic control of Fasciola hepatica in Brazil.     

F A Echevarria  M B Correa  R D Wehrle  I F Correa 《Veterinary parasitology》1992,43(3-4):211-222

Two separate field trials involving naturally infected cattle were carried out on two farms known to have a history of Fasciola hepatica infection. On the first farm, 15 animals per group were allocated as follows: G1, triclabendazole (TCBZ) four times a year; G2, TCBZ twice a year (May and September); G3, untreated control. All groups grazed together and after 3.5 years the animals were slaughtered and their livers examined by federal meat inspectors who condemned 100% of livers in G3 and 8.3% in G2 owing to the presence of lesions of fasciolosis. In G1 no livers were condemned. Significant differences in weight gains were not detected and fluke counts remained at low levels in the treated groups. Also, in the control group, egg counts started to decrease when animals were 2 years old. On the second farm, groups of 20 animals were treated as follows: G1, TCBZ three times a year (May, September and December); G2, TCBZ twice a year (May and September); G3, nitroxynil twice a year (May and September); G4, rafoxanide twice a year (May and September); G5, untreated controls. All animals were weighed and faecal samples examined at approximately 28-day intervals. During the period of the study, larger weight gains were detected in the TCBZ treated groups than in the others. TCBZ treatment kept F. hepatica egg counts at a lower level for longer periods than the other drugs and significant differences in weight gains were only obtained between the group receiving TCBZ three times a year and the control group.  相似文献   

Survival and symbiotic properties of Bradyrhizobium japonicum in the presence of thiram: isolation of fungicide resistant strains     

J. A. Andrés  N. S. Correa  S. B. Rosas 《Biology and Fertility of Soils》1997,26(2):141-145

The fungicide thiram, widely used as a chemical seed protectant, induces a strong inhibition of primary nodulation in the crown zone of soybean roots. The present work reports on the isolation of Bradyrhizobium japonicum strains resistant to thiram, some of which (T3B, A86 and A2) maintained their capacity for nodulation and were still efficient symbionts, but some (A1, C1 and C6) lost the ability to stimulate nodulation. Characterization tests such as growth at different pH, denitrifying ability, salt tolerance, production of siderophores and phosphate solubilization were performed on the resistant strains. Inoculants produced from these strains could be appropriate for use with thiram-treated seeds, without causing a loss of bacteria viability. Received: 16 September 1996  相似文献   

Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin     

Aspholm-Hurtig M  Dailide G  Lahmann M  Kalia A  Ilver D  Roche N  Vikström S  Sjöström R  Lindén S  Bäckström A  Lundberg C  Arnqvist A  Mahdavi J  Nilsson UJ  Velapatiño B  Gilman RH  Gerhard M  Alarcon T  López-Brea M  Nakazawa T  Fox JG  Correa P  Dominguez-Bello MG  Perez-Perez GI  Blaser MJ  Normark S  Carlstedt I  Oscarson S  Teneberg S  Berg DE  Borén T 《Science (New York, N.Y.)》2004,305(5683):519-522

Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.  相似文献   

Methodology for selective coffee harvesting in management zones of yield and maturation     

Kazama  Elizabeth Haruna  da Silva  Rouverson Pereira  Tavares  Tiago de Oliveira  Correa  Lígia Negri  de Lima Estevam  Francisca Nivanda  Nicolau  Francisca Edcarla de Araújo  Maldonado Júnior  Walter 《Precision Agriculture》2021,22(3):711-733

Precision Agriculture - The non-uniformity of coffee fruit maturation is an intrinsic plant condition that is not favorable for the beverage quality. This could be overcome by using the precision...  相似文献   

Attributes of stand-age-dependent forest determine technosol fertility of Atlantic forest re-growing on mining tailings in Mariana,Brazil     

Pedro Manuel Villa  Sebasti 《林业研究》2022,33(1):103-116

Understanding how soil fertility changes due to environmental conditions and stand-age-dependent for-est attributes is important for local-scale forest restoration.We evaluated the effects of stand-age-dependent forest attributes (plant community composition and litter stock)on soil and technosol fertility across two second-growth Atlantic forests (SGF) after the deposition of mining tail-ings in Mariana,southeastern Brazil.We hypothesized that technosol fertility in the SGF tailings is positively affected by plant community composition variability,stand age,and litter stock.We used total exchangeable bases and organic matter as fertility indicators for technosol and soil,and spe-cies composition and litter stock as stand-age-dependent forest attributes.Our results showed significant differences in the stand-age-dependent forest attributes and soil chemi-cal properties between the two forest patches (SGF tailing and SGF non-tailing) evaluated.Thus,there was a marked gradient of litter storage and fertility between soil and tech-nosol that can be important forest recovery indicators for the affected plant communities.Furthermore,according to the tested models,we corroborated the hypothesis that techno-sol fertility is positively affected by stand age,plant com-munity composition variability,and litter stock,which may contribute considerably to forest recovery on tailings.Our results demonstrate that the fertility predictors analyzed to explain the forest recovery on tailings can also be considered as ecological indicators for assessing forest restoration in areas impacted by mining tailings in Mariana.  相似文献   

Comparative evaluation of novel African swine fever virus (ASF) antibody detection techniques derived from specific ASF viral genotypes with the OIE internationally prescribed serological tests   总被引：2，自引：0，他引：2  

C. Gallardo  A. Soler  R. Nieto  A.L. Carrascosa  G.M. De Mia  R.P. Bishop  C. Martins  F.O. Fasina  E. Couacy-Hymman  L. Heath  V. Pelayo  E. Martín  A. Simón  R. Martín  A.R. Okurut  I. Lekolol  E. Okoth  M. Arias 《Veterinary microbiology》2013

The presence of antibodies against African swine fever (ASF), a complex fatal notifiable OIE disease of swine, is always indicative of previous infection, since there is no vaccine that is currently used in the field. The early appearance and subsequent long-term persistence of antibodies combined with cost-effectiveness make antibody detection techniques essential in control programmes. Recent reports appear to indicate that the serological tests recommended by the OIE for ASF monitoring are much less effective in East and Southern Africa where viral genetic and antigenic diversity is the greatest. We report herein an extensive analysis including more than 1000 field and experimental infection sera, in which the OIE recommended tests are compared with antigen-specific ELISAs and immuno-peroxidase staining of cells (IPT). The antibody detection results generated using new antigen-specific tests, developed in this study, which are based on production of antigen fractions generated by infection and virus purification from COS-1 cells, showed strong concordance with the OIE tests. We therefore conclude that the lack of success is not attributable to antigenic polymorphism and may be related to the specific characteristics of the local breeds African pigs.  相似文献   

Response of Potato (Solanum tuberosum L.) Germplasm to Water Stress Under In Vitro Conditions     

Macarena Barra  José Correa  Erika Salazar  Boris Sagredo 《American Journal of Potato Research》2013,90(6):591-606

Chile is center of origin and diversity of potato (Solanum tuberosum L.). Potato yield is affected under water stress conditions, so development of varieties with better tolerance to this stress is desirable. In this study we determined the differential response of INIA-Chile potato germplasm to water stress under in vitro assays with polyethylene glycol. One-hundred-and-fourty-nine genotypes were evaluated. Polyethylene glycol 4.8 % w/v was able to distinguish genotype response by considering the morphological variables (plantlet height, leaf and root number) and fresh and dry weight. Through multivariate statistical analysis, and in comparison with their respective controls without treatment, genotypes were clustered with high (74 – 79 %), intermediate (29 – 94 %), low (29 – 57 %), and very low (4– 28 %) water stress tolerance. The high-tolerance-response cluster was mainly made up of Chilean potato landraces. These results highlight the importance of this germplasm in food security, which could be directly cultivated and/or be used as progenitors to produce new varieties with increased tolerance to water-deficit stress.  相似文献   

Sensors for product characterization and quality of specialty crops—A review     

M. Ruiz-Altisent  L. Ruiz-Garcia  Renfu Lu  E.C. Correa  B. Nicolaï 《Computers and Electronics in Agriculture》2010,74(2):176-194

This review covers developments in non-invasive techniques for quality analysis and inspection of specialty crops, mainly fresh fruits and vegetables, over the past decade up to the year 2010. Presented and discussed in this review are advanced sensing technologies including computer vision, spectroscopy, X-rays, magnetic resonance, mechanical contact, chemical sensing, wireless sensor networks and radio-frequency identification sensors. The current status of different sensing systems is described in the context of commercial application. The review also discusses future research needs and potentials of these sensing technologies. Emphases are placed on those technologies that have been proven effective or have shown great potential for agro-food applications. Despite significant progress in the development of non-invasive techniques for quality assessment of fruits and vegetables, the pace for adoption of these technologies by the specialty crop industry has been slow.  相似文献   

Production and economic assessment of giant kelp Macrocystis pyrifera cultivation for abalone feed in the south of Chile          下载免费PDF全文

Tomás Correa  Alfonso Gutiérrez  Roberto Flores  Alejandro H Buschmann  Patricio Cornejo  Cristian Bucarey 《Aquaculture Research》2016,47(3):698-707

Kelp biomass availability for mass abalone cultivation remains a critical issue in Chile. The technical and economic feasibility of a commercial scale kelp farming activity has not been established. This study describes the production and economic results of a pilot scale unit installed in southern Chile. Our results show 25 kg m^?1 of production over a 9‐month spring‐summer period, and 16.2 kg m^?1 during the autumn‐winter period. These values indicate that a total biomass production of 41.3 kg (wet) ma^?1 year^?1 can be obtained by placing the culture lines at 4 m intervals. High quality animal food‐grade plants with a 9% protein content, over 5 m in length were harvested. Sensitivity analysis showed that by cultivating 30–50 ha with a market value of US$ 78 ton^?1, a return on investment can be made after the first year.  相似文献