Composición y calidad de la leche en función de la etapa de lactancia y de la paridad

The purpose of this work was to evaluate the relationship among lactation order and days in milking with milk production, composition and somatic cells count (SCC) from Holstein cows and also verify the efficiency of "California Mastitis Test” (CMT) to detect high scores of SCC. Milk samples were collected from the Experimental Farm of Iguatemi located in Maringa, Parana State, from 2008 to 2009. Regression analyzes were performed by a computer system R (2009) in order to verify the behavior of production and milk components as a function of days of lactation order and using the mixed model methodology, considering animal and day of milk control as random. To evaluate the efficiency of CMT test in detecting high SCC was considered negative binomial distribution for the response variable, because it is data that exhibit over dispersion, using the methodology of generalized linear models. It was found that milk production increases and milk fat decreases by the lactation order. Milk protein increases with the days in milking because milk production is decreased. It was concluded that milk production and quality are closely connected to the lactation order and days in milking and CMT performed on farm is positively linked with CCS.El objetivo de este estudio fue evaluar la relación entre el orden y los días de lactancia con la producción, composición y conteo de células somáticas (CCS) en leche de vacas Holstein, así como comprobar la eficacia de la prueba California para Mastitis (CMT) detectando alto CCS. Se tomaron muestras de leche del rebaño de la Hacienda Experimental de Iguatemi, Maringá-PR, en un periodo comprendido entre 2008 y 2009. Fueron realizados análisis de regresión utilizando el programa estadístico R (2009) con el fin de verificar el comportamiento de la producción y los componentes de la leche en función de los días y orden de lactancia utilizando la metodología de modelos lineares mixtos, considerando el animal y día de control lechero como aleatorios. Para evaluar la eficacia de la prueba de CMT para detectar alto CCS se consideró distribución binomial negativa para la variable respuesta, ya que los datos mostraron sobredispersión utilizando la metodología de modelos lineales generalizados. Se encontró que a medida que la producción de leche aumenta, el porcentaje de grasa en la leche disminuye, siendo diferente en cada orden de lactancia. El porcentaje de proteína aumenta con el periodo de lactación, mientas disminuye la producción. Se concluye que la producción y la calidad de la leche están estrechamente relacionadas con el orden y los días de lactación, la prueba CMT tiene relación positiva con el CCS

Cassava processing wastewater as a platform for third generation biodiesel production

ABSTRACT This study aimed to evaluate third generation biodiesel production by microalgae Phormidium autumnale using cassava processing wastewater as a platform. Experiments were performed in a heterotrophic bubble column bioreactor. The study focused on the evaluation of the bioreactor (batch and fed-batch) of different operational modes and the analysis of biofuel quality. Results indicate that fed-batch cultivations improved system performance, elevating biomass and oil productions to 12.0 g L−1 and 1.19 g L−1, respectively. The composition of this oil is predominantly saturated (60 %) and monounsaturated (39 %), resulting in a biodiesel that complys with U.S., European and Brazilian standards. The technological route developed indicates potential for sustainable production of bulk oil and biodiesel, through the minimization of water and chemical demands required to support such a process