Cow-specific risk factors for clinical mastitis in Brazilian dairy cattle.

Information related to mastitis risk factors is useful for the design and implementation of clinical mastitis (CM) control programs. The first objective of our study was to model the risk of CM under Brazilian conditions, using cow-specific risk factors. Our second objective was to explore which risk factors were associated with the occurrence of the most common pathogens involved in Brazilian CM infections. The analyses were based on 65 months of data from 9,789 dairy cows and 12,464 CM cases. Cow-specific risk factors that could easily be measured in standard Brazilian dairy farms were used in the statistical analyses, which included logistic regression and multinomial logistic regression. The first month of lactation, high somatic cell count, rainy season and history of clinical mastitis cases were factors associated with CM for both primiparous and multiparous cows. In addition, parity and breed were also associated risk factors for multiparous cows. Of all CM cases, 54% showed positive bacteriological culturing results from which 57% were classified as environmental pathogens, with a large percentage of coliforms (35%). Coagulase-negative Staphylococcus (16%), Streptococcus uberis (9%), Streptococcus agalactiae (7%) and other Streptococci (9%) were also common pathogens. Among the pathogens analyzed, the association of cow-specific risk factors, such as Zebu breed (OR=5.84, 95%CI 3.77-10.77) and accumulated history of SCC (1.76, 95%CI 1.37-2.27), was different for CM caused by Coagulase-negative Staphylococcus and S. agalactiae in comparison to CM caused by coliforms. Our results suggest that CM control programs in Brazil should specially consider the recent history of clinical mastitis cases and the beginning of the lactations, mainly during the rainy season as important risk factor for mastitis.

Vacinação com Escherichia coli J5 no pré-parto e ocorrência de mastite e produção de leite de vacas mestiças leiteiras / Escherichia coli J5 vaccination during pre-calving and mastitis and milk production of crossbred cows

Avaliaram-se a utilização da vacina Escherichia coli J5 no período pré-parto e a ocorrência de mastite e de produção de leite. Foram utilizadas 93 vacas, sendo 43 vacinadas e 50 não vacinadas. Para a análise dos dados de produção e CCS (contagem de células somáticas), utilizou-se delineamento inteiramente ao acaso em sistemas de parcelas subdivididas. Os dados de CCS e duração de casos clínicos de mastite foram transformados em Log10CCS. Para as médias de CCS e a duração de casos clínicos, usou-se o teste t. Para comparações de médias de recidivas de casos clínicos, usou-se o teste de Mann-Whitney. Para frequência de microrganismos e de mastite subclínica, usou-se o teste de qui-quadrado. A interação dessas variáveis foi analisada pelo teste de McNemar. Não houve redução na prevalência de infecções por coliformes entre a secagem e o parto nos dois grupos. A duração total dos casos clínicos de mastite em animais que apresentaram mastite clínica foi menor em vacas vacinadas. O número de episódios clínicos e a intensidade dos casos clínicos não diferiu entre os grupos. A prevalência de animais com mastite subclínica no pós-parto e a (CCS) nos 100 primeiros dias de lactação foram mais baixas no grupo de animais vacinados. Não foi observada diferença na produção de leite entre os grupos. A vacinação de vacas com E. coli J5 melhora a saúde da glândula mamária de vacas leiteiras e, consequentemente, reduz a prevalência de animais com mastite subclínica no pós-parto, bem como a duração dos casos clínicos de mastite e a CCS nos 100 primeiros dias de lactação.

The effect of immunization with Escherichia coli J5 vaccine in the pre-partum on the occurrence of mastitis and milk production in crossbred dairy cows was evaluated. Ninety-three cows were used as follows: forty-three were vaccinated and fifty cows were unvaccinated. For the production analysis, data and CCS were used in a completely randomized split-plot system. CCS data and duration of clinical cases of mastitis were transformed into Log10CCS. For the CSS averages and duration of clinical cases we used the t test. For comparisons of means of recurrences of clinical cases we used the Mann-Whitney test. For frequency of subclinical mastitis organisms and we used the chi-square test. The interaction of these variables was analyzed using the McNemar test. There was no reduction in the prevalence of infections caused by coliforms between drying-off and parturition in both groups. The total duration of clinical mastitis in animals with clinical mastitis was lower in vaccinated than unvaccinated cows. The number of clinical episodes and intensity of clinical cases did not differ between groups. The prevalence of animals with subclinical mastitis at postpartum and somatic cell count (SCC) in the first 100 days of lactation was lower in vaccinated than unvaccinated cows. However, there was no difference in milk production between groups. Vaccination of cows with E. coli J5 improves mammary gland health by reducing the prevalence of animals with subclinical mastitis at postpartum, as well as the duration of the clinical cases of mastitis and SCC in the first 100 days of lactation.

Croton sonderianus essential oil samples distinctly affect rat airway smooth muscle.

Plants of the genus Croton have been used extensively in the northeast of Brazil for treating various clinical conditions. Previous studies have demonstrated that the essential oil of some specimens of Croton sp. have a relaxing effect on tracheal smooth muscle. Our study aimed to characterize the effects of Croton sonderianus essential oil samples, collected at 1:00 pm (EO-13) and 9:00 pm (EO-21), on rat tracheal smooth muscle. The two samples were submitted to gas chromatography (GC) and mass spectrometry (MS) analysis to identify their components. Rat tracheal smooth muscle strips were used to assess the biological activity. The major constituents of EO-21 were: spathulenol (18.32%), beta-caryophyllene (14.58%) and caryophyllene oxide (8.54%) and the major constituents of EO-13 were bicyclogermacrene (16.29%), beta-phellandrene (15.42%) and beta-caryophyllene (13.82%). These samples showed an antispasmodic effect on tracheal smooth muscle strips pre-contracted with high K+ concentration (80 mM) or with acetylcholine. EO-21 increased baseline tonus while EO-13 provoked a decrease. These results demonstrated that EO-13 and EO-21 have different chemical composition and showed myorelaxant activity. In conclusion, EO-13 and EO-21 may have potential therapeutic use in the treatment of bronchospasm.