Big-leaf mahogany (Swietenia macrophylla King) is the woody species with the highest economic value in Latin America. Currently, it is subject to intensive exploitation, diminishing its natural populations. Due to this decline, the species is a preferred species for reforestation and establishment of commercial tropical plantations. Mycorrhizal symbiosis is a biotic factor scarcely studied in the ecology of this species. Therefore, the objective of this research was to identify the diversity of arbuscular mycorrhizal fungi (AMF) species associated with the rhizosphere of seedlings and mature trees of big-leaf mahogany growing in its natural habitat, a tropical rain forest in Los Tuxtlas, Veracruz, Mexico. Soil samples from a 20-cm depth were taken from the rhizosphere of big-leaf mahogany seedlings and mature trees. Additionally, spores from the rhizosphere soil were propagated on Sorghum vulgare, isolated and identified. The percentage of AMF colonization was also evaluated.

El objetivo del estudio fue caracterizar los componentes del sistema de producción (SP) bovino doble propósito (DP) en el Distrito de Desarrollo Rural (DDR) 151 y determinar la tipología de las unidades de producción (UP) dentro del SP DP, usando variables sociales, económicas y tecnológicas. Se analizó información de 46 UP del SP DP que participaron en el programa soporte de la Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación (Sagarpa) 2013-2014. A través del uso de análisis de conglomerado y análisis de varianza fueron identificados y caracterizados tres tipos de UP: Tradicional (44%), Transición (30%) y Empresarial (26%). Las UP Empresarial se diferenciaron (p < 0.05) de las de tipo Tradicional y en Transición por poseer mayor superficie, número de vacas, volumen de producción de leche e índice tecnológico, circunstancias que les permitieron obtener mayores ingresos por venta de leche y becerros.

Se determinó el rendimiento y calidad del forraje en un sistema silvopastoril con Leucaena leucocephala cv. Cunningham (5000 árboles ha^-1) asociado con Megathyrsus maximus cv. Tanzania, en cuatro intervalos de descanso (20, 30, 40 y 50 d), en dos épocas (lluvias y seca) en clima cálido Subhúmedo. Los tratamientos se distribuyeron aleatoriamente a las unidades experimentales (12 parcelas, 24 m² c/u) y se evaluó el rendimiento y calidad nutritiva del forraje en la época húmeda (agosto-octubre, 2014) y seca (marzo-abril, 2015). La gramínea aportó la mayor proporción de forraje a la biomasa disponible (80 vs. 20%) y se produjo más biomasa total a 50 días en lluvias (5300 kg MS ha^-1) y seca (1620 kg MS ha^-1); en lluvias, la proteína cruda (PC) de los arboles aumentó gradualmente a 22% (P0.05); fibra detergente neutro (FDN) se mantuvo (44%) (P>0.05) y fibra detergente ácido (FDA) aumentó (25%) (P<0.05) a 50 días, mientras digestibilidad in vitro de la materia seca (DIVMS) disminuyó (49%) (P<0.05). En la gramínea, la PC (10%) (P<0.001) y DIVMS (58 %) se mantuvieron hasta 40 días y después declinaron (P<0.03), aunque FDN y FDA aumentaron significativamente a 50 días, en ambas épocas. la asociación L. leucocephala y M. maximus, alcanza su mayor producción entre 40-50 días, con mejor calidad nutritiva de la gramínea a 40 días, que se puede compensar con el valor nutritivo del follaje de los árboles hasta los 50 días de descanso, independientemente de la época.

Criollo and Suffolk ewes were compared for resistance to an experimental infection with Haemonchus contortus in the periparturient period. Measures on days -28, -14, 0 (lambing date), 14, 28, and 42 were taken on number of eggs per gram of faeces (EPG), packed cell volume (PCV), blood eosinophil numbers (BEN), and body weight (BW) in 28 Criollo and 25 Suffolk ewes. One half of the ewes of each genotype was inoculated orally with 3000 L3 of H. contortus in a single dose. Phenotypic correlations between response variables were estimated. Criollo ewes had lower means than Suffolk ewes for EPG (570.7 +/- 208.1 vs. 1363.9 +/- 245.5) and BW (50.4 +/- 1.2 vs. 81.0 +/- 1.4 kg), and a higher mean for PCV (35.0 +/- 0.6 vs. 32.7 +/- 0.6%). BW of inoculated Criollo ewes increased from day -28 to day 42, while that of inoculated Suffolk ewes decreased. Non-inoculated Criollo and Suffolk ewes had slightly increased BW from day -28 to lambing date; after lambing, BW of inoculated Suffolk ewes decreased, while that of inoculated Criollo ewes increased. Birth type and lambing number affected (p < .05) EPG, PCV, and BW. Negative correlations were found (p < .01) between EPG and PCV with BW. Criollo ewes were more resistant than Suffolk ewes to H. contortus.

The objective was to integrate the information of the local milk production system, physicochemical and microbiological characteristics of the milk; elaboration process, and physicochemical, microbiological, and sensory characteristics of cheese to establish its typicity. The manufacturing of the cheese in most of the dairies studied has registered the operation of three generations of families. Variability in their chemical composition, microbiological, colour, texture and sensory was related with time and number of turns during the pressing, amount of added salt and vegetal fat. Cheeses with less pressing time had higher moisture content and less protein and fat content. The bacterial counts were related to milk quality tests, training courses and material of containers. These factors also affected the hardness of the cheese. Those with added vegetable fat and with high salt content had the highest hardness. The Hue angle (h°) of the cheeses indicated a tonality close to yellow (90°). Difference in chromaticity (C*) can be related to the use of vegetable fat. Cheeses with higher moisture content were brighter (L*) and had less color saturation. The sensory evaluation showed that the most typical cheeses were perceived in the attributes as salty, milk aroma, and serum and milking smell. Applying sanitation measures of milk collection, good cheese manufacturing practices and avoiding the addition of vegetable fat, it could be possibly getting a legal-commercial protection of the ranchero Jarocho cheese.