Effect of subclinical mastitis on the yield and cheese-making properties of ewe's milk

[EN] This review covers an update of scientific knowledge about productive and technological consequences of subclinical mastitis in sheep milk. The literature reports individual milk yield losses of 2.6-43.1 %, being modulated by several factors as infection severity, production level, causal agents, and unilateral or bilateral IMI (1 or 2 infected glands, respectively). A compensatory increase of milk production from the uninfected gland when only one half was infected has been quantified in 6.6 %, compared with healthy halves of control sheep. This compensatory adaptation highlights the risk of underestimating subclinical mastitis in sheep. The mammary gland response is quick and milk yield losses in absolute terms remained constant within the following weeks, both when infection appear during lactation and when it is present from lambing. With respect to the changes on main components in milk due to subclinical mastitis it has been clearly established a decrease in the concentration of lactose and an increase of that of whey proteins. The role played by lactose as an osmotic regulator results in a more accentuated decrease of its concentration in milk. This is why lactose is considered at present as a reliable potential indicator of subclinical mastitis. Whey proteins increase as a result of the increase of the blood-milk barrier permeability and the increased proteolysis of caseins. However, the content in milk of fat and casein are modified depending on the magnitude of milk yield reduction, being affected by a concentration or dilution effect. In any case, the ratio casein to protein (parameter independent of the milk volume) decreases as a result of infection. The impairment of physical and chemical characteristics due to decreased udder health status is the responsible of the negative effect of increased SCC on the coagulation properties of milk, the curd yield and the quality of cheese. Low ratio of casein to protein in high bulk tank SCC milk enhances the extension of the rennet coagulation time (RCT) and curd firming time (k20) because there are more serum proteins and the stability of casein micelles are reduced as a result of hydrolysis. Those changes in turn led to poor syneresis, lower cheese yield, increased moisture content and lower fat and protein content in cheese. Finally, there is a favourable relationship between lactose and milk technological properties because the decrease of this component in case of mastitis is associated with an increase of milk pH. Thus, the three parameters, SCC, pH, and lactose affect, contemporarily and independently, milk quality and coagulation properties, and this is why have been highlighted as potential indicators traits for improving cheese-making ability of sheep milk.This review is based on knowledge gained during work financially supported by means of a research fellowship from the regional government of Valencia ("Generalitat Valenciana").Martí-De Olives, A.; Peris Ribera, CJ.; Molina Pons, MP. (2020). Effect of subclinical mastitis on the yield and cheese-making properties of ewe's milk. Small Ruminant Research. 184:1-7. https://doi.org/10.1016/j.smallrumres.2019.106044S17184Albenzio, M., Marino, R., Caroprese, M., Santillo, A., Annicchiarico, G., & Sevi, A. (2004). Quality of milk and of Canestrato Pugliese cheese from ewes exposed to different ventilation regimens. 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Journal of Dairy Science, 96(12), 7698-7708. doi:10.3168/jds.2013-6998Martí-De Olives, A., Navarro-Ríos, M. J., Rubert-Alemán, J., Fernández, N., & Molina, M. P. (2015). Composition, proteolysis indices and coagulating properties of ewe milk as affected by bulk tank somatic cell count. Journal of Dairy Research, 82(3), 344-349. doi:10.1017/s0022029915000394Merin, U., Fleminger, G., Komanovsky, J., Silanikove, N., Bernstein, S., & Leitner, G. (2008). Subclinical udder infection withStreptococcus dysgalactiaeimpairs milk coagulation properties: The emerging role of proteose peptones. Dairy Science and Technology, 88(4-5), 407-419. doi:10.1051/dst:2008022Park, Y. W. (2007). Rheological characteristics of goat and sheep milk. Small Ruminant Research, 68(1-2), 73-87. doi:10.1016/j.smallrumres.2006.09.015Paschino, P., Vacca, G. M., Dettori, M. L., & Pazzola, M. (2019). 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Mujer y desarrollo rural. Influencia de las políticas comunitarias destinadas al fomento de la igualdad de oportunidades

La preocupación por las consecuencias negativas que multitud de actividades humanas ejercían de forma sistemática sobre el medio ambiente, comenzó a tomar fuerza a partir de los años 60, plasmándose este aumento de concienciación en eventos internacionales tales como la conferencia celebrada por las Naciones Unidas en Estocolmo en junio de 1972, donde se puso de manifiesto la necesidad de poner en marcha iniciativas de protección ambiental encaminadas a conseguir un desarrollo social “perdurable”, es decir, un desarrollo capaz de satisfacer las necesidades humanas del presente, pero sin arriesgar las posibilidades de las generaciones futuras. Este primer evento, aunque no tuvo consecuencias muy eficientes, supuso el motor de arranque para que posteriormente, en 1983, la comunidad internacional apoyase la propuesta de la ONU de crear una Comisión Mundial sobre el Medio Ambiente y el Desarrollo, llegando ésta a la conclusión de que para satisfacer "las necesidades del presente sin comprometer la capacidad de las futuras generaciones" la protección del medio ambiente y el crecimiento económico habrían de abordarse como una sola cuestión. Ya en los años noventa, la Asamblea General de las Naciones Unidas, convocó la Conferencia de las Naciones Unidas sobre el Medio Ambiente y el Desarrollo (CNUMAD). Esta conferencia, conocida como “Cumbre para la Tierra”, celebrada en Río de Janeiro en junio de 1992, supuso un aspecto clave para el comienzo de las negociaciones a nivel internacional sobre las cuestiones relacionadas con el medio ambiente y desarrollo. Los objetivos fundamentales de la Cumbre eran lograr un equilibrio justo entre las necesidades económicas, sociales y ambientales de las generaciones presentes y futuras, sentar las bases para una asociación mundial entre países desarrollados y en desarrollo, así como entre los gobiernos y los sectores de la sociedad civil, para la actuación sobre las necesidades y los intereses comunes. 2 Fueron aprobados, por un total de 172 gobiernos incluidos 108 Jefes de Estado y de Gobierno, tres grandes acuerdos que habrían de regir la labor futura. Uno de ellos fue conocido como el Programa 21, consistente en un plan de acción mundial para promover el desarrollo sostenible. En él, donde se llegaron a recopilar más de 2500 recomendaciones prácticas para abordar los problemas urgentes actuales, también se ofrecieron diversas maneras de fortalecer el papel de lo que se ha venido a llamar como “grupos principales” entre los que se destaca de forma explícita, entre otros, a las mujeres. Asimismo, en la Declaración de Río, donde se definieron los derechos y obligaciones de los Estados respecto a los principios básicos sobre el medio ambiente y el desarrollo, se formuló como idea clave, entre otras, el convencimiento de que la plena participación de la mujer era considerada imprescindible para el logro de un desarrollo sustentable. Centrándonos en el caso de la situación de la mujer en el entorno rural, cabe destacar la fuerte masculinización que históricamente y en un ámbito geográfico global ha caracterizado a este espacio, produciendo esta circunstancia que a menudo la situación de la mujer quedase relegada a un papel secundario, siendo considerada en numerosas ocasiones como mera colaboradora de las tareas desempeñadas por el hombre. Esta situación ha provocado que frecuentemente el papel de la mujer careciese de reconocimiento tanto social como económico, frenando de esta forma su potencial productivo personal, así como de forma general, un mayor desarrollo del conjunto del medio al que pertenece. De esta realidad y con el objetivo de acabar con esta situación de desigualdad, durante las últimas reformas de la Política Agraria Comunitaria (PAC)- donde el desarrollo rural constituye su segundo pilar de actuación- aparece un conjunto de políticas de igualdad de oportunidades, siendo éstas consideradas como un objetivo imprescindible para un avance eficiente del medio rural. Es por ello que la perspectiva de género actualmente constituye un elemento esencial presente en cualquier política y estrategia formulada, con la finalidad de garantizar a las mujeres la igualdad de oportunidades tanto a nivel laboral, como político o cultural. Por otra parte, cabe destacar que debido al carácter reciente del interés por mejorar las circunstancias y condiciones de las mujeres rurales (principios de los años ochenta), la información actual sobre este colectivo es todavía escasa, limitándose casi exclusivamente a análisis localizados. Es por ello que se hace necesario impulsar trabajos que analicen de forma pormenorizada, la situación de la mujer y que éstos sirvan de base de decisión para las futuras políticas de actuación

Composition, proteolysis índices and coagulating properties of ewe milk as affected by bulk tank somatic cell count

[EN] The aim of this study was to assess the effect of ovine bulk tank somatic cell count (BTSCC) on composition,proteose-peptone (p-p) content and casein fractions as indicating parameters for proteolysis and coagulating properties of milk. A total of 97 samples of bulk tank milk from Manchega breed ewe flocks were grouped according to somatic cell count (SCC) into four classes: fewer than 500 000 cells/ml, from 500 000 to 10 00 000 cells/ml, from 10 00 000 to 15 00 000 and more than 15 00 000 cells/ml. The casein : protein ratio and lactose content decreased with BTSCC. Proteolysis increased with BTSCC, causing a drop in β-casein and an increase in the γ-caseins from a concentration of 500 000 cells/ml. Regarding coagulation behaviour, the rennet clotting time (RCT) and firming time (k20) rose from 10 00 000 15 00 000 cells/ml of milk. The results showed that the impairment of milk quality and milk ability to make cheese as affected by intramammary infection (IMI) can be inferred from the bulk tank milk of flocks with poor udder health.The Regional Government of Valencia ('Generalitat Valenciana') participated in funding this paper through a research fellowship in whose context this work was carried out. The authors would like to thank the Regional Centre of Animal Selection and Reproduction (Valdepenas, Ciudad Real) and the Forlasa S.A. cheese company (Villarrobledo, Ciudad Real) for their invaluable help and collaboration in the experiment.Martí De Olives, AM.; Navarro Rios, MJ.; Rubert Aleman, J.; Fernández Martínez, N.; Molina Pons, MP. (2015). Composition, proteolysis índices and coagulating properties of ewe milk as affected by bulk tank somatic cell count. Journal of Dairy Research. 82(3):344-349. doi:10.1017/S0022029915000394S34434982

Quantification of milk yield and composition changes as affected by subclinical mastitis during the current lactation in sheep

[EN] The aim of this work was to quantify, on a half-udder basis, the changes in ewe milk yield and composition caused by unilateral subclinical mastitis within the current lactation. Fluctuations due to production level, infection severity, time from the onset of infection, and lactation curves were also studied. Yield and composition of milk from half-udders of unilateral infected ewes were compared between them and with a set of healthy halves using a mixed model. The experiment was completed with a whole-udder approach on the same animals. To test the effect of intramammary infection (IMI) in the 7 wk following the onset of infection, 20 ewes that acquired unilateral subclinical mastitis during lactation and 40 healthy ewes were used. Another group of 20 unilaterally infected ewes from wk 1 of lactation and other 40 healthy ewes were studied to test the effect of IMI on lactational milk yield and composition. The individual milk loss in ewes infected during lactation was 15% for the 7 wk following the onset of infection, and 6.6% more milk was produced by the uninfected half to compensate milk lost by the infected half. Lactational milk yield loss in ewes infected from wk 1 postpartum was 17%. The changes in milk yield were noticed from the week of infection diagnosis. The production level of animals influenced the milk yield changes caused by IMI in such a way that the more productive ewes lost more milk, although these losses were proportional to their production level. On the other hand, infection severity affected milk loss between glands, being more pronounced as somatic cell count increased. A clear decrease of lactose content and casein:protein ratio due to subclinical IMI was observed and it remained throughout the postinfection period. Improving udder health status is necessary to maintain milk production and quality in dairy ewes during lactationThe authors thank the regional government of Valencia ("Generalitat Valenciana") for its support by means of a research fellowship.Martí De Olives, AM.; Díaz, J.; Molina Pons, MP.; Peris Ribera, CJ. (2013). Quantification of milk yield and composition changes as affected by subclinical mastitis during the current lactation in sheep. Journal of Dairy Science. 96(12):7698-7708. doi:10.3168/jds.2013-6998S76987708961

Short communication: Goat colostrum quality: Litter size and lactation number effects

The quality of colostrum of Murciano-Granadina goats was studied to establish the transition period and the time when milk can be marketed. Forty-three dairy goats were used: 19 primiparous (15 single births; 4 multiple births) and 24 multiparous (10 single births; 14 multiple births). Samples were collected every 12 h during the first week postpartum. Physicochemical parameters and somatic cell count were determined. Analysis of variance with repeated measures was used to study the effect of different factors: postpartum time, litter size, lactation number, their interactions, and production level on colostrum. Postpartum time had a significant effect on all parameters studied, which decreased along the first week of lactation, whereas lactose, pH, and conductivity increased. Based on these results, colostrum secretion takes place until 36 h postpartum (hpp). In relation to other factors of variation studied, the lactation number influenced most colostrum components, whereas the litter size only affected the pH value, protein and lactose content. The production level influenced only the protein and dry matter contents, with an inverse relationship. Milk produced during the period between 36 and 96 hpp is considered transition milk, which should not be commercialized. Milk collected after 4 d postpartum (96 hpp) could be marketed, ensuring that its composition does not present a risk in the dairy industry.This work was part of the AGL-2009-11524 Project funded by the Spanish Ministry of Science and Innovation (Madrid, Spain). The authors are grateful to ZEU-Inmunotec (Zaragoza, Spain) for their support.Romero Rueda, T.; Beltrán Martínez, MC.; Rodríguez Garcia, M.; Marti-De Olives A.; Molina Pons, MP. (2013). Short communication: Goat colostrum quality: Litter size and lactation number effects. Journal of Dairy Science. 96(12):7526-7531. https://doi.org/10.3168/jds.2013-6900S75267531961

Mamitis y calidad de la leche de oveja

El conocimiento de los efectos de la mamitis subclínica sobre la calidad de la leche de oveja resulta de gran importancia de cara a evaluar las pérdidas ocasionadas y su incidencia tecnológica. El estado sanitario de la ubre parece tener una influencia significativa sobre algunos componentes de la leche, produciéndose un aumento de los constituyentes procedentes de la sangre (albúmina, inmunoglobulinas, iones cloro y sodio) y una reducción de los sintetizados en la glándula mamaria (grasa y lactosa), así como un aumento del pH y una reducción de la acidez titulable. Estas modificaciones de la composición de la leche a causa de las mamitis se traducen en cambios en su comportamiento durante la elaboración de productos lácteos derivados, que conllevan pérdidas de rendimiento quesero y deterioro de la calidad de los quesos. Otro problema de gran importancia ligado a las mamitis es la posible presencia en la leche de residuos de antibióticos y otros medicamentos utilizados en su tratamiento, que pueden tener graves consecuencias para la salud pública desde el punto de vista toxicológico, así como un efecto negativo sobre la calidad tecnológica de la leche. Frente a esta problemática, en los últimos años, se están realizando diferentes trabajos de investigación en ovejas para establecer los valores de células somáticas indicadores de mamitis subclínicas, y los efectos de éstas sobre las pérdidas de producción y calidad de la leche, que permitirán completar la Directiva Comunitaria 92/46 en cuanto al límite máximo de células somáticas para la leche de oveja y cabra

Situación de la mujer en el medio rural de la Región de Murcia

Del estudio de campo realizado queda patente que las mujeres del medio rural, en comparación con sus compañeros varones, poseen significativamente un mayor grado de formación académica, comprobando que la desigualdad en ámbito de la formación ha desaparecido. No ocurre lo mismo en el ámbito laboral donde esa mayor cualificación no se ve recompensada por una igualdad de oportunidades en campo del trabajo. Ello es constatado por los datos obtenidos acerca del alto porcentaje de mujeres que trabajan dentro de la economía sumergida, el alto índice de empleo no estable y la baja antigüedad del último empleo desempeñado. Consecuencia de ello surge el alto índice de mujeres que afi rman no estar contentas con su situación laboral y que buscan una mejora en su empleo. La causa principal de esta situación, se encuentra directamente relacionada con los resultados obtenidos acerca de las fuertes responsabilidades familiares que las mujeres rurales todavía tienen que asumir en el cuidado del hogar y de las personas dependientes, con una ayuda muy descompensada por parte de la pareja y del resto de los componentes de la unidad familiar. Esto se ve agravado además por la menor oferta de servicios de atención a personas dependientes, lo que arrastra a las mujeres en mayor medida a buscar fórmulas que les permitan compatibilizar el trabajo en el ámbito doméstico con su realización profesional, con la consiguiente disminución de oportunidades de empleo más satisfactorias y adecuadas a su nivel formativo. Tras todos estos aspectos, suele subyacer la persistencia de una serie de valores patriarcales, generadores de roles desiguales de género, que reducen las oportunidades vitales y laborales de las mujeres rurales. Estos valores mantienen una fuerza en este ámbito que parece superior al registrado en los medios más urbanos. La carencia de servicios para la atención a las personas dependientes es un factor que explica en parte estas diferencias.Frente a este panorama, muchas mujeres muestran su insatisfacción con su situación sociolaboral, y demandan nuevas salidas y oportunidades, manifestando la necesidad de un cambio intergeneracional de actitudes y valores, con la reivindicación de sus derechos y con ello de una mayor igualdad de género. Aparecen nuevos yacimientos de empleo (turismo rural, agricultura ecológica), al mismo tiempo que se desarrolla el asociacionismo entre las mujeres, con vías para canalizar las demandas de estas mujeres

Effect of subclinical mastitis on proteolysis in ovine milk

The aim of this work was to evaluate the effect of intramammary infection (IMI) on the endogenous proteolysis of milk. Four control checks were carried out in the half-udder milk of 10 ewes that acquired unilateral subclinical mastitis. Two of these checks were conducted before the infection was established and 2 after. Ten healthy ewes were tested as a control group. The presence of a subclinical IMI involved an increase of the products of casein hydrolysis, the proteose-peptone (p-p) fraction and minor (m) caseins, and a decrease of ß-casein. As a result, a significant increase in the proteolysis index (PI), calculated as the ratio of m-casein to the sum of caseins (¿ + ß + ¿), took place ¿-Casein and ¿-casein were not significantly affected by IMI. Correlations confirmed the scenario: log 10 of somatic cell count (SCC) was positively correlated with p-p content and negatively with ß-casein, whereas log 10 SCC was not correlated with ¿-casein or ¿-casein. On the other hand, p-p content was positively correlated with m-casein and PI and negatively with ß-casein, but no correlation was detected between p-p content and ¿- or ¿-casein. Furthermore, between casein fractions, m-casein was only significantly correlated with ß-casein. These results suggest that use of indices of proteolysis of caseins such as p-p, m-casein, and PI, could be applied together with SCC to evaluate the cheese-making quality of milk. © 2011 American Dairy Science Association.The authors thank the regional government of Valencia ("Generalitat Valenciana") for its support by means of a research fellowship in which context this work was done.Marti-De Olives A.; Le Roux, Y.; Rubert-Alemán J.; Peris Ribera, CJ.; Molina Pons, MP. (2011). Effect of subclinical mastitis on proteolysis in ovine milk. Journal of Dairy Science. 94(11):5369-5374. doi:10.3168/jds.2011-4269S53695374941