Sexually dimorphic plants provide an excellent opportunity for examining the differences in the extent of their defense against herbivores because they exhibit sex-related differences in reproductive investment. Such differences enable comparison of the sex with high reproduction expenses with the sex that expends less. The more costly sex is usually also better defended against herbivores. Generally, females are considered more valuable than hermaphrodites in terms of fitness; however, hermaphrodites are more valuable if they can produce seed by autonomous selfing, provided that the inbreeding depression is low and pollen is limited. We studied a gynodioecious population of Opuntia robusta from Central-Eastern Mexico, which has been reported to be trioecious, dioecious, or hermaphrodite, and addressed the following questions: 1) Is the hermaphrodite's reproductive output higher than the female's, and are hermaphrodites thus better defended? 2) Are plant tissues differentially defended? 3) Do trade-offs exist among different physical defense traits? and 4) among physical and chemical defense traits? We found that 1) hermaphrodites had a higher seed output and more spines per areola than females and that their spines contained less moisture. Non-reproductive hermaphrodite cladodes contained more total phenolic compounds (TPCs) than female ones. In addition, 2) hermaphrodite reproductive cladodes bore more spines than female cladodes, and 3) and 4) we found a negative relationship between spine number per areola and areola number per cladode and a positive relationship between spine number per areola per plant and TPC concentration per plant. Non-reproductive hermaphrodite cladodes contained a higher concentration of TPCs than female cladodes, and parental cladodes contained fewer TPCs than both reproductive and empty cladodes.

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RESUMENSe evaluaron las características químicas y sensoriales de la carne de cerdos alimentados con Ractopamina (RAC) a 5 ppm (Paylean ® , Elanco, México) y diferentes concentraciones de lisina digestible ileal estandarizada (lys-dig), en dietas con 3.3 Mcal EM/ kg y 14.5 % de proteína cruda, lo que representa un contenido de proteína de 10 % inferior al mínimo recomendado por el laboratorio y la literatura. Se utilizaron 48 cerdos (peso corporal inicial 77.2±3.42 y final 110.0±3.0 kg) que fueron asignados a uno de cuatro tratamientos: C) Dieta de finalización Control (lys-dig 0.65%); RAL) alta en Lisina con RAC (lys-dig 1%); RNL) Niveles normales de lisina con RAC (lis-dig 0.80%); RBL) Baja en lisina con RAC (lis-dig 0.50%). Después de 28 días en sus respectivas dietas, los animales se sacrificaron y procesaron. De cada animal, se recolectaron cuatro chuletas (2.5 cm de grosor) y se determinó grasa intramuscular y evaluación sensorial. Los resultados indican que con la adición de RAC, en dietas con 14.5 % de proteína, se aumenta (P<0.01) la grasa intramuscular en 25 %. Un incremento mayor (hasta el 50 %) en grasa intramuscular se obtuvo con dietas con RAC y una baja concentración de lisina (0.5% lys-dig). El panel de consumidores no detectó diferencias en aroma, sabor y textura (P>0.17), pero sí detectó una mayor jugosidad de carne de cerdo (P<0.02) de animales que consumieron la dieta RBL. Es factible mejorar la calidad de la carne de cerdo mediante el uso de RAC y dietas bajas en proteína y lisina. PALABRAS CLAVE 428María Antonia Mariezcurrena-Berasain, et al. / Rev Mex Cienc Pecu 2012;3(4):427-437 INTRODUCCIÓNUna alternativa para aumentar la competitividad, es la obtención de productos diferenciados. En la carne de cerdo, la grasa intramuscular (GIM) puede ser un factor de diferenciación de producto a nivel comercial (1) que influye positivamente en la suavidad (2) , el aroma y la jugosidad (3,4) , así como en la aceptación general de la carne (4,5) .Además de la genética (6) , otra forma de incrementar el contenido de GIM en la carne de cerdo es mediante el suministro de dietas deficientes en proteína durante la fase final de la engorda (7,8) , especialmente cuando la concentración de lisina es baja (9,10) . Sin embargo, estas dietas reducen la eficiencia alimenticia y la tasa de crecimiento (11) .El clorhidrato de ractopamina (RAC, Paylean ® , Elanco una división de Eli Lilly Co., México) es una fenatolamina con actividad agonista -adrenérgica usada como promotor del crecimiento, que mejora la eficiencia alimenticia y el rendimiento de la canal (12,13) . Smith (14) sugiere que la RAC promueve que los nutrientes sean orientados más enfáticamente a la síntesis de proteína muscular, además de que reduce la tasa de degradación de proteínas, lo que acaba promoviendo la hipertrofia muscular (15) .El laboratorio que produce la RAC en forma comercial, así como diversos estudios (16,17) , recomiendan su uso con dietas que contengan un mínimo de 16 % de proteína cruda (PC) para alcanzar la concentración adec...

Aiming to evaluate sowing densities and efficiency of radiation use, six corn genotypes, three from open pollination (“Amarillo Almoloya,” “Cacahuacintle,” and “Jiquipilco”) and three hybrids (“Z-60,” “Condor,” and “H-50”), were sown at densities of 6.9, 7.8, and 8.9 plants m−2, under a split plot design, within a factorial arrangement of treatments during three years (2008, 2009, and 2010). Evaluated variables were yield, harvest index, biomass production, attenuation coefficient, and radiation use efficiency. Results indicate that 2008 was the best year because yield, biomass, and radiation use efficiency were 1132.6, 3505 gm−2, and 0.79 g MJ−1, respectively. “Jiquipilco” was the genotype that exhibited the best adaptability to climatic conditions of the zone; thus, it is recommended to be grown on the studied zone.

Functional biocompounds beneficial for animals and humans are in Mexican folk herbs. Cuphea and Eryngium species presented antimicrobial potential. Natural antibiotic uses by ethnoveterinary research with medicinal plants in equine infection or digestive diseases need more scientific evidence. Staphylococcus aureus, Escherichia coli, Salmonella enterica serotype Enteritidis are etiological agents in horses responsible for stable infections, abortions, fetal or perinatal deaths, and resistant intrahospital infections. The main objective of the present research was to evaluate the potential of antimicrobial and antioxidant activities of two Mexican medicinal plants Cuphea aequipetala var. hispida (Cav.) Koehne and Eryngium comosum Delaroche F over Listeria monocytogenes ATCC 19115, Staphylococcus sp., E. coli ATCC 25922, and S. enterica serotype Enteritidis ATCC 13076 bacterium reference strains related to equine infections. Determination of total phenol, saponins, antioxidant activity (ABTS), and antimicrobial activity with diffusion-sensitive discs was performed in triplicate. All the strains were sensitive for both extracts except for E. coli strain that was inhibited only by C. aequipetala. Staphylococcus sp. and S. enterica strains were inhibited equally by both extracts. E. comosum extracts tested have shown the highest effect over L. monocytogenes. In summary, antimicrobial activity was similar to the reported activity of Eryngium species extracts with other different solvents. Present extracts are suggested as a potential alternative antibiotic; definitely, more specific equine pathogen inhibition tests are needed in feed additives for horse nutrition research. In conclusion, antimicrobial activities of Cuphea aequipetala var. hispida (Cav.) Koehne and Eryngium comosum Delaroche F over reference strains related to equine infections suggested these medicinal plants as potential antibiotic sources for horse diseases.