Lucinéia Mestieri

Effect of somatic cell count and mastitis pathogens on milk composition in Gyr cows.

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.

Milk flow, teat morphology and subclinical mastitis prevalence in Gir cows

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 2nd and 3rd 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

EFFECT OF MICROBIOLOGICAL CHARACTERISTICS OF RAW MILK ON THE QUALITY OF WHOLE MILK POWDER

Neste trabalho, avaliou-se a relacao entre a qualidade do leite em po integral e os principais parâmetros microbiologicos do leite empregado como materia-prima, utilizando-se 16 lotes de leite padronizado quanto aos teores de gordura e solidos nao gordurosos. Os niveis medios de microrganismos mesofilos e psicrotroficos do produto em po foram 7,8 x 101 e 4,0 x 101 UFC/g, respectivamente, sendo que estes valores estiveram correlacionados significativamente (P < 0,05) com as contagens de mesofilos e psicrotroficos do leite cru (niveis medios de 8,1 x 106 e 1,8 x 107 UFC/g, respectivamente). Observou-se, tambem, uma correlacao significativa (P < 0,05) entre a contagem de psicrotroficos do leite cru e o teor de acidez titulavel do produto em po, cujos valores variaram de 0,15 a 0,19% (em acido latico). As amostras de leite em po produzido a partir de leite cru contendo niveis elevados de psicrotroficos apresentaram maiores indices de insolubilidade, porem, a correlacao entre estes parâmetros nao foi significativa. Discute-se a importância do controle das condicoes higienicas do leite cru, como instrumento fundamental para garantir a qualidade do produto em po oferecido ao consumo.

Prediction of bovine milk true protein content by mid-infrared spectroscopy

The aim of this study was to estimate the concentration of milk true protein (TP) by mid-infrared absorbance method (MIR) in samples from bulk tank of dairy herds, and to determine the correlation between the results of TP of milk determined by Kjeldahl and MIR. Forty nine dairy herds were selected (17 Holstein, 6 Jersey and 26 Girolando) for monthly collections of samples from bulk tanks during the period of one year (284 samples). Fat, lactose, crude protein and total solids were firstly determined by MIR, and then analyzed for total and true protein by Kjeldahl method. The regression equation to estimate TP contents based on MIR crude protein determination was as follows: TP=0.0021+(1.0104xCP), where: TP is the content of true protein, CP is the crude protein content determined by the MIR method, and 0.0155 is the model error term.