Estimativa do teor de proteína verdadeira do leite bovino por espectroscopia na região do infravermelho médio

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.O objetivo deste estudo foi estimar o teor de proteína verdadeira (PV) do leite por meio de metodologia de espectroscopia na região do infravermelho médio (IVM), em amostras de tanque de rebanhos leiteiros comerciais, e determinar a correlação entre os resultados de proteína verdadeira do leite determinados pelo método de Kjeldahl e por IVM. Foram selecionados 49 rebanhos leiteiros (17 da raça Holandesa, seis da raça Jersey e 26 da raça Girolando) para coletas mensais de amostras de leite de tanque durante o período de um ano, totalizando 284 amostras analisadas. As amostras de leite foram analisadas inicialmente em relação aos teores de gordura, lactose, proteína bruta e sólidos totais por IVM, sendo em seguida analisadas quanto ao teor de PB e PV pelo método de Kjeldahl. A equação de regressão para estimativa do teor de PV com base nos teores de proteína bruta foi a seguinte: PV=0,0021+(1,0104xPB); em que: PV é o teor de proteína verdadeira estimado; PB é o teor de proteína bruta pelo método IVM e 0,0155 é o erro apresentado pelo modelo

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

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 2ª ou 3ª 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.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 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 Efeito das características microbiológicas do leite cru sobre a qualidade do leite em pó integral

The relationship between microbiological characteristics of raw milk and the quality of high-heat whole powder made from it was investigated. To this end, 16 lots of milk standardized for fat and non-fat solids were used. Powder average levels of mesophiles and psychrotrophs were 7.8 x 10¹ and 4.0 x 10¹ CFU/g, respectively, and these values correlated positively (P < 0.05) with the corresponding raw milk counts (8.1 x 10(6) and 1.8 x 10(7) CFU/g, respectively). A significant positive correlation (P < 0.05) was also observed between raw milk psychrotroph counts and titratable acidity of milk powder (range: 0.15 - 0.19 as % lactic acid). Samples of powder produced from raw milk with higher psychrotroph levels were found to have higher insolubility indexes, yet this relationship was not statistically significant. The importance of milk hygienic control as a basic instrument to warrant commercial milk powder quality is discussed.<br>Neste trabalho, avaliou-se a relação entre a qualidade do leite em pó integral e os principais parâmetros microbiológicos do leite empregado como matéria-prima, utilizando-se 16 lotes de leite padronizado quanto aos teores de gordura e sólidos não gordurosos. Os níveis médios de microrganismos mesófilos e psicrotróficos do produto em pó 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 mesófilos e psicrotróficos do leite cru (níveis médios de 8,1 x 10(6) e 1,8 x 10(7) UFC/g, respectivamente). Observou-se, também, uma correlação significativa (P < 0,05) entre a contagem de psicrotróficos do leite cru e o teor de acidez titulável do produto em pó, cujos valores variaram de 0,15 a 0,19% (em ácido lático). As amostras de leite em pó produzido a partir de leite cru contendo níveis elevados de psicrotróficos apresentaram maiores índices de insolubilidade, porém, a correlação entre estes parâmetros não foi significativa. Discute-se a importância do controle das condições higiênicas do leite cru, como instrumento fundamental para garantir a qualidade do produto em pó oferecido ao consumo

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

Abstract Background Gyr 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. Results Subclinical 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. Conclusions Intramammary 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

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

Abstract Background Gyr 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. Results Subclinical 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. Conclusions Intramammary 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

Fluxo de leite, morfometria de tetos e a prevalência de mastite subclínica em vacas Gir

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 2ª ou 3ª 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 ordenhaThe 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 milkin