Factores alimenticios que influyen en la calidad de la carne de rumiantes

En la actualidad, mejorar la calidad de la carne es el nuevo desafío para ganaderos e investigadores, y uno de los factores extrínsecos de mayor influencia sobre la calidad de la canal y la carne en los rumiantes es la alimentación de los animales, en especial los alimentos proteínicos y energéticos, así como las vitaminas, los minerales y los promotores del crecimiento. El nivel de aporte de estos elementos a los sistemas de producción extensiva, intensiva o mixta, es determinante; por ejemplo, la apariencia de la canal de los bovinos alimentados a base de pastoreo es la pigmentación amarilla de la grasa de cobertura de la canal. Para animales en confinamiento se ha demostrado que la energía en la dieta influye en la terneza de la carne, como consecuencia del incremento del contenido de grasa de infiltración presente en el músculo. Sin embargo, la manipulación del perfil y el porcentaje de ácidos grasos,especialmente polinsaturados, y el ácido linoleico conjugado, pueden ser modificados con la dieta del animal, junto con la integración de minerales y antioxidantes como el selenio, el magnesio y la vitamina E. Al margen del resto de los factores que también influyen sobre la calidad de la carne, se deben incluir aspectos de análisis sensorial relacionado con la dieta de los animales

PERFIL DE LOS ÁCIDOS GRASOS Y SUS MODIFICACIONES EN LA CALIDAD DE LA CARNE DE LOS BOVINOS

The challenge for food researchers is to improve the quality of the lipids that are integrated in meat, with the purpose of the consumer reducing the intake of saturated fats, as a factor in life quality. To achieve this objective, it is necessary to understand the different factors that influence livestock production. Genetics and gene expression are interesting lines of research, which attempt to explain how genomics can benefit the quality of the fat in adipocytes. There are also several extrinsic factors, perhaps the most important one being the diet and addition of some specific nutrients. However, the problem is not as simple as it seems, and study factors with simulation models as well as physicalchemical and sensory analyses that solve the problem should be involved. A description of some factors that are associated with the quality of the meat lipids, which can be regulated primarily by the livestock breed or genetic group, genus, nutrition and production systems, was carried out.El desafío de los investigadores en alimentos es mejorar la calidad de los lípidos que se integran en la carne con la finalidad de que el consumidor reduzca la ingesta de grasas saturadas como un factor de calidad de vida. Para lograr este objetivo es necesario conocer los diferentes factores que influyen en la producción ganadera. La genética y expresión de genes son líneas interesantes de investigación que tratan de explicar cómo la genómica puede beneficiar la calidad de la grasa en los adipocitos. También hay varios factores extrínsecos; quizás el más importe es la alimentación y adición de algunos nutrientes en específico. Sin embargo, el problema no es tan sencillo como parece; se deben involucrar factores de estudio con modelos de simulación y análisis físico-químicos y sensoriales que resuelvan el problema. Se realizó una descripción de algunos factores que se asocian con la calidad de los lípidos en la carne que pueden estar regulados principalmente por la raza o grupo genético de ganado, género, nutrición y sistemas de producción

EMPAQUE PARA LA CONSERVACIÓN DE CARNE Y PRODUCTOS CÁRNICOS

La carne y los productos cárnicos tienen varias manipulaciones antes de llegar al consumidor final; por ello, es importante elegir correctamente el método de preservación a utilizar. Los empaques tienen la función de conservar y proteger el producto con la finalidad de mantener su integridad y calidad. En esto último, la inocuidad, el color, la frescura de la carne o productos cárnicos derivados, juegan un papel decisivo para que el consumidor decida o no adquirirlo. Los procesos más utilizados para empacar las carnes frescas y derivados cárnicos son: el empacado permeable al aire, en atmósferas modificada y al vacío. En este trabajo se indican las pautas mínimas necesarias en este rubro indispensable de la cadena de valor de la carne y productos cárnicos

Exploiting Reliability-Guided Aggregation for the Assessment of Curvilinear Structure Tortuosity

The study on tortuosity of curvilinear structures in medical images has been significant in support of the examination and diagnosis for a number of diseases. To avoid the bias that may arise from using one particular tortuosity measurement, the simultaneous use of multiple measurements may offer a promising approach to produce a more robust overall assessment. As such, this paper proposes a data-driven approach for the automated grading of curvilinear structures’ tortuosity, where multiple morphological measurements are aggregated on the basis of reliability to form a robust overall assessment. The proposed pipeline starts dealing with the imprecision and uncertainty inherently embedded in empirical tortuosity grades, whereby a fuzzy clustering method is applied on each available measurement. The reliability of each measurement is then assessed following a nearest neighbour guided approach before the final aggregation is made. Experimental results on two corneal nerve and one retinal vessel data sets demonstrate the superior performance of the proposed method over those where measurements are used independently or aggregated using conventional averaging operators

Comparison of two phenotypical methods to segregate resistant and susceptible lambs to parasitic nematodes

The objective of this study was to compare two segregation methods to select resistant and susceptible female Pelibuey lambs infected naturally with gastrointestinal nematodes (GINs) in relation to their haematological and immunological response. For 6 months, faeces and blood samples were taken fortnightly from 40 grazing 5-month-old female lambs. The lambs were classified according to two methods using faecal egg count (FEC) as a phenotypical trait. In the first (reference) method (M3SE, n = 22), resistant (RES) lambs had FEC lower than the mean – 3 standard errors, the susceptible (SUS) lambs levels higher than + 3 standard errors(n = 10) and the intermediate (INT) lambs (n = 8) were categorised by having FECs between the two values. The second method (QUM) divided the population, using quartiles, into resistant (RES; 25%), intermediate (INT; 50%), and susceptible (SUS; 25%) lambs. The agreement between both methods was estimated using the Kappa index. The packed cell volume (PCV), total plasma protein (TPP) and peripheral eosinophils (EOS) were determined for each group. Serum was used to evaluate the IgA levels. PCV and TPP values were higher (P<0.01) in the RES lambs (31.5 ± 3.4 and 6.16 ± 0.5 g/dL by QUM, respectively, and 31.5 ± 3.9 and 6.24 ± 0.49 g/dL by M3SE, respectively) than the SUS lambs (28.1 ± 4.7 and 5.94 ± 0.5 g/d, respectively, by both methods). The EOS and IgA values increased with age. M3SE and QUM were in moderate agreement (Kappa = 0.43). We concluded that the two segregation methods allowed for the identification of the same female SUS lambs, but a greater number of animals were categorised phenotypically as resistant using the M3SE method. PCV and TPP can help to identify phenotypically resistant animals

Productive response of lambs fed with fresh or dehydrated spineless cactus (Opuntia ficus-indica L.)

Abstract The objective of this study was to evaluate the effect of cactus (Opuntia ficus-indica L.) supplementation on lamb animal performance, during a 11-week period. For this purpose, 27 male lambs of commercial crossbreeds were used, with initial live weight mean of 21.4±3.8 kg. They were distributed homogeneously into three groups of nine each, and then randomly assigned to each of the following treatments: (T1) control diet, (2) diet with 17% (dry matter basis) of dehydrated cactus, and (3) diet with 17% (dry matter basis) of fresh cactus. Digestibility in situ of the diet, dry matter intake (DMI), daily gain weight (DGW), feeding conversion (FC) and efficiency (FE), back fat, hot and cold carcass yield, biological hot and cold carcass yield, and carcass pH at slaughtering and 24h post mortem, were evaluated. A completely random design using Proc GLM was used, and when statistical differences were observed, a mean comparison was done using the Tukey test. There were significant differences (P≤0.001) on DM digestibility, with higher value (42.0%) on the control diet during the first 6 hours of incubation, but after 48 hours, the highest digestibility (88.6%) was on the fresh cactus diet. There were not significant differences (P>0.05) between treatments on animal performance, except on back fat, being higher (P<0.001) on dehydrated (4.1 mm) and fresh (3.3 mm) diets, compared to the control one (7.8 mm). The means for hot and cold carcass yield, biological hot and cold carcass yield, and carcass pH at slaughtering and 24h post mortem were 50.6%, 47.0%, 55.4%, 49.5%, 6.6% and 5.8%, respectively. Diet including cactus had similar effect on productive parameters than that of the commercial one, which makes it a viable feeding strategy, and from the economical point of view, could be attractive to the farmer, since the cactus is a plant that grows over the year. However, there is a need of doing more research to confirm these results, not only on fattening lambs, but also on the different animal life stages, considering different levels of cactus, and working on different animal breed and species

The spatial analysis of biological interactions:Morphological variation responding to the co-occurrence of competitors and resources

By sharing geographic space, species are forced to interact with one another and the contribution of this process to evolutionary and ecological patterns of individual species is not fully understood. At the same time, species turnover makes that species composition varies from one area to another, so the analysis of biological interaction cannot be uncoupled from the spatial context. This is particularly important for clades that show high degree of specialization such as hummingbirds, where any variation in biotic pressures might lead to changes in morphology. Here, we describe the influence of biological interactions on the morphology of Hylocharis leucotis by simultaneously considering potential competition and diet resources. We characterized the extent of local potential competition and local available floral resources by correlating two measurements of hummingbird diversity, floral resources and the size of morphological space of H. leucotis along its geographic distribution. We found that H. leucotis shows an important morphological variability across its range and two groups can be recognized. Surprisingly, morphological variation is not always linked to local hummingbird richness or the phylogenetic similarity of. Only in the southern part of its distribution, H. leucotis is morphologically more variable in those communities where it coexist with closely related hummingbird species. We also found that morphological variation in H. leucotis is independent from the availability of floral resources. Our results suggest that abiotic factors might be responsible for morphological differences across populations in Hylocharis leucotis being biological interactions of minor importance.</p

Hydraulics of skimming flows on stepped chutes: The effects of inflow conditions?

Modern stepped spillways are typically designed for large discharge capacities corresponding to a skimming flow regime for which flow resistance is predominantly form drag. The writer demonstrates that the inflow conditions have some effect on the skimming flow properties. Boundary layer calculations show that the flow properties at inception of free-surface aeration are substantially different with pressurized intake. The re-analysis of experimental results highlights that the equivalent Darcy friction factor is f similar to 0.2 in average on uncontrolled stepped Chute and f similar to 0.1 on stepped chute with pressurized intake. A simple design chart is presented to estimate the residual flow velocity, and the agreement of the calculations with experimental results is deemed satisfactory for preliminary design

Problemas productivos y reproductivos por deficiencias minerales en bovinos de algunas regiones tropicales de México

Los minerales son considerados nutrientes esenciales para el organismo. En las zonas tropicales de México, se presenta una problemática de calidad de los forrajes, su contenido de proteína y aporte de minerales son bajos. Las condiciones climáticas influyen en el contenido de minerales en el suelo, plantas y en los animales. Se reportan bajos contenidos de Ca, P, Zn, Se, I y Cu, en la relación suelo-planta-animal. La presencia de algunas enfermedades carenciales se refleja con baja producción de leche y carne, hay efectos negativos en la fertilidad, abortos, baja calidad de semen, retención de placenta, partos distócicos, entre otros. Es importante suplementar los minerales carenciales en el ganado, con el propósito de mejorar la eficiencia productiva. Se debe evitar el exceso de minerales para prevenir efectos contaminantes al ambient

Telomerase activity, estrogen receptors (α, β), Bcl-2 expression in human breast cancer and treatment response

BACKGROUND: The mechanism for maintaining telomere integrity is controlled by telomerase, a ribonucleoprotein enzyme that specifically restores telomere sequences, lost during replication by means of an intrinsic RNA component as a template for polymerization. Among the telomerase subunits, hTERT (human telomerase reverse transcriptase) is expressed concomitantly with the activation of telomerase. The role of estrogens and their receptors in the transcriptional regulation of hTERT has been demonstrated. The current study determines the possible association between telomerase activity, the expression of both molecular forms of estrogen receptor (ERα and ERβ) and the protein bcl-2, and their relative associations with clinical parameters. METHODS: Tissue samples from 44 patients with breast cancer were used to assess telomerase activity using the TRAP method and the expression of ERα, ERβ and bcl-2 by means of immunocytochemical techniques. RESULTS: Telomerase activity was detected in 59% of the 44 breast tumors examined. Telomerase activity ranged from 0 to 49.93 units of total product generated (TPG). A correlation was found between telomerase activity and differentiation grade (p = 0.03). The only significant independent marker of response to treatment was clinical stage. We found differences between the frequency of expression of ERα (88%) and ERβ (36%) (p = 0.007); bcl-2 was expressed in 79.5% of invasive breast carcinomas. We also found a significant correlation between low levels of telomerase activity and a lack of ERβ expression (p = 0.03). CONCLUSION: Lower telomerase activity was found among tumors that did not express estrogen receptor beta. This is the first published study demonstrating that the absence of expression of ERβ is associated with low levels of telomerase activity