BackgroundGyr cows are well adapted to tropical conditions, resistant to some tropical diseases and have satisfactory milk production. However, Gyr dairy herds have a high prevalence of subclinical mastitis, which negatively affects their milk yield and composition. The objectives of this study were (i) to evaluate the effects of seasonality, mammary quarter location (rear x front), mastitis-causing pathogen species, and somatic cell count (SCC) on milk composition in Gyr cows with mammary quarters as the experimental units and (ii) to evaluate the effects of seasonality and somatic cell count (SCC) on milk composition in Gyr cows with cows as the experimental units. A total of 221 lactating Gyr cows from three commercial dairy farms were selected for this study. Individual foremilk quarter samples and composite milk samples were collected once a month over one year from all lactating cows for analysis of SCC, milk composition, and bacteriological culture.ResultsSubclinical mastitis reduced lactose, nonfat solids and total solids content, but no difference was found in the protein and fat content between infected and uninfected quarters. Seasonality influenced milk composition both in mammary quarters and composite milk samples. Nevertheless, there was no effect of mammary quarter position on milk composition. Mastitis-causing pathogens affected protein, lactose, nonfat solids, and total solids content, but not milk fat content. Somatic cell count levels affected milk composition in both mammary quarters and composite samples of milk.ConclusionsIntramammary infections in Gyr cows alter milk composition; however, the degree of change depends on the mastitis-causing pathogen. Somatic cell count is negatively associated with reduced lactose and nonfat solids content in milk. Seasonality significantly affects milk composition, in which the concentration of lactose, fat, protein, nonfat solids and total solids differs between dry and wet seasons in Gyr cows.

The objectives of this study were (1) to determine the sensitivity (Se) and specificity (Sp) of somatic cell count (SCC) thresholds to identify subclinical mastitis in Gyr cows caused by major and minor pathogens; (2) to study the effects of month of sampling, rear or front mammary quarters, herd, intramammary infection (IMI), and bacterial species on SCC at quarter level; and (3) to describe the prevalence of IMI in Gyr cows in commercial dairy herds. In total, 221 lactating Gyr cows from 3 commercial dairy farms were selected. Milk samples were collected from individual quarters once a month for 1 yr from all lactating cows for SCC and bacteriological analysis. Mammary quarters were considered the experimental units and the SCC results were log(10)-transformed. Four SCC thresholds (100, 200, 300 and 400 × 10(3) cells/mL) were used to determine Se and Sp to identify infected mammary quarters. The overall prevalence of IMI in quarter milk samples of Gyr cows was 49.8%, and the prevalence of minor pathogens was higher (31.9%) than that of major pathogens (17.8%). Quarter samples with microbial isolation presented higher SCC compared with negative samples. Sensitivity and Sp of selected SCC thresholds varied according to the group of pathogen (major and minor) involved in the IMI definition. Sensitivity increased and Sp decreased when mammary quarters with only major pathogens isolation were considered positive. The use of a single SCC analysis to classify quarters as uninfected or infected in Gyr cows may not be a useful test for this breed because Se and Sp of SCC at the studied thresholds were low. The occurrence of IMI and the bacterial species are the main factors responsible for SCC variation in mammary quarters of Gyr cows. Milk samples with major pathogens isolation elicited higher SCC than those with minor pathogens.

-The aim of this work was to evaluate the association between milk flow, teat morphological measurements and subclinical mastitis prevalence in Gir cows. Eighty cows in the 2 nd and 3 rd lactations, with 90 to 200 days of lactation, were divided according to milk flow during milking into fast or slow groups. Teat morphometry was assessed by ultrasound scanning of the right anterior teat and external measurements. Milk samples were collected for somatic cells count (SCC) and microbiological culture. The effect of milk flow during milking was evaluated by analysis of variance of milk yield, SCC, morphometry and external measurements. The association of morphometry and external measurements of the teats with the SCC and microorganisms found in milk were analysed. Milk flow was significantly correlated to milk production. Gir cows with slower milk flow had longer teat canal and greater milk yield, in comparison to cows with fast milk flow. Teat-end to floor distance influenced SCC of Gir cows. Prevalence of subclinical mastitis and the type of mastitis-causing pathogens were not affected by milk flow during milking.Index terms: Gir, lactation, mammary gland, milking, morphology. Fluxo de leite, morfometria de tetos e a prevalência de mastite subclínica em vacas GirResumo -O objetivo deste trabalho foi avaliar a associação entre o fluxo de leite, a morfometria dos tetos e a prevalência de mastite subclínica em vacas Gir. Oitenta vacas em 2 a ou 3 a lactação, com 90 a 200 dias de lactação, foram divididas, de acordo com o fluxo de leite durante a ordenha, nos grupos rápido ou lento. A morfometria de tetos foi avaliada por imagens de ultrassom do teto anterior direito e medidas externas dos tetos. Amostras de leite foram coletadas para a contagem de células somáticas (SCC) e a cultura microbiológica. O efeito do fluxo de leite durante a ordenha foi avaliado pela análise de variância de produção de leite, SCC, morfometria e medidas externas dos tetos. Foi analizada a associação entre a morfometria e medidas externas dos tetos e a SCC e microganismos encontrados no leite. O fluxo de leite foi significativamente correlacionado à produção de leite. As vacas Gir com fluxo de leite mais lento tinham maior comprimento de canal dos tetos e maior produção de leite, em comparação a vacas de fluxo rápido. A distância do teto ao solo influenciou a SCC das vacas Gir. A prevalência de mastite subclínica e o tipo de microrganismo causador de mastite não foram alterados pelo fluxo de leite durante a ordenha.Termos para indexação: Gir, lactação, glândula mamária, ordenha, morfologia.

Pesquisa de anticorpos anti-Brucella canis e anti- AbstractDogs brucellosis may cause reprodutive problems and there are a risk factors for human health. The prevalence of brucellosis due to Brucella canis and Brucella abortus was investigated in dogs living in urban areas of São João da Boa Vista/SP -Brasil. For this purpose, 500 blood sample were collected and serum analysed by agar gel immunodiffusion test and Rose-Bengal test. The frequency of brucellosis due to B. canis was 4/500 (0,8%) and negative for B. abortus.

MALEK DOS REIS, C. B. Avaliação da contagem de células somáticas do leite como indicador da ocorrência de mastite em vacas Gir.[Evaluation of milk somatic cell count as an indicator of mastitis occurence in Gyr cows]. 2010.122 f. Dissertação (Mestrado em Ciências)