Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Six models to estimate genetic parameters for birth weight (BW), weaning weight adjusted to 205 days (W205), and yearling weight adjusted to 365 days (W365) were compared. Model A included direct genetic effects. Model AP allowed for direct genetic and permanent environmental effect of the dam. Model AM included direct genetic and maternal genetic effects. Models AMC and AMP were the same as Model AM but they also allowed for the covariance between direct and maternal genetic effects, and the common environmental effect due to the dam, respectively; and Model AMCP was fitted for all three random effects plus the covariance between direct and maternal effects. Models were compared using the likelihood ratio text. The AMC model was selected to be the most appropriate for BW and W205, whereas Model A was chosen for W365. When maternal effects were included, direct genetic variance and direct heritability estimates were reduced for BW and W205. Direct heritability estimates with appropriate models were: 0.13, 0.21 and 0.20 for BW, W205 and W365. Heritability of maternal effects with appropriate models was: 0.15 and 0.32 for BW and W205, and direct-maternal genetic correlations with appropriate models were: -0.67 and -0.69 for BW and W205, respectively. 

The neem tree (Azadirachta indica A. Juss.) is known for its insecticidal properties. In this study an extraction method for neem seeds based on cold extrusion with methanol was applied. On the resulting extract (azadirex), limonoids azadirachtin A and B (AZA and AZB), salannin, and nimbin were quantified by HPLC. A 10 years old neem orchard was used (19° 11.65’ N, 96° 20.07’ W). The extrusion of 1.0 kg of dry endocarp, ground seeds previously immersed in 150 mL of methanol during 20 min, was performed in a manual hydraulic press, at 20 kg cm-2 and room temperature. Concentration of limonoids underwent an analysis of variance and means separation (Tukey, P < 0.05). The seed with endocarp showed a salannin concentration of 4500 mg kg-1, 3450 mg kg-1 of nimbin and 2784 mg kg-1 of the azadirachtins A and B mixture. Azadirex had a typical composition of AZA, AZB, nimbin and salannin, however the latter (3866 mg kg-1) was found in a significantly higher proportion compared to the others (Tukey, P < 0.05). No significant differences were found between the mixture of AZA + AZB (1818 mg kg-1) and nimbin (1280 mg kg-1).

El frijol ejotero es un cultivo que responde al suministro de nitrógeno (N), por lo que en este estudio se determinó la mejor combinación de fertilizante y biofertilizante para aumentar la biomasa, rendimiento y calidad nutricional del frijol ejotero. La siembra se realizó en el Estado de México, bajo un diseño experimental de bloques al azar, con cuatro repeticiones. Los tratamientos fueron: 0, 100 y 200 kg N ha-1, biofertilizante (mezcla de Rhizobium etli + Glomus intraradices), y la combinación de N + biofertilizante. No hubo diferencias en la fenología (P > 0.05) por efecto del fertilizante. El biofertilizante + 200 kg N ha-1 produjo el mayor rendimiento, número de ejotes y porcentaje de proteína (2131 g m-2, 486 ejotes m2 y 22 %, respectivamente), y el grupo control produjo los más bajos (983 g m-2, 278 ejotes m2 y 20.5 %, respectivamente). En biomasa total, los valores más altos fueron para biofertilizante + 200 kg N ha-1 p (649 g m-2), y los más bajos (150 g m-2) para el control. El índice de cosecha más alto (46 %) se obtuvo con la aplicación de biofertilizante + 100 kg N ha-1.

In Mexico, poor crop rotation has affected the capacity of soil to produce; the use of maize genotypes with higher yield potential and more intensive production systems has increased the demand for inputs, which affects the economy of the producer. To determine the effect of changes in input prices and the main factors that explain the supply of maize grain in Guanajuato, in the present work an econometric model was estimated; comprised of two supply equations, three transmission prices and an identity for the period from 1980 to 2009. The results indicate that the supply of maize grain in the state responds inelastically to changes in the producer price of maize produced under irrigation and elastically if changes arise in the same price level but the offer temporary, with elasticities own-price 0.8531 and 1.0604, changes in input prices that more affect the state offer are the pesticide and labor price, with cross-price elasticities of -0.6154 and -0.5470, changes in the competitive product that more impact are those in the bean, with cross-price elasticities of -0.5489, if produced under irrigation and -1.0292 if produced in temporary. The effect of price transmission, indicate that the producer price of maize under irrigation and temporary state is directly influenced by the wholesale price at a rate of 0.79 and 0.80% for each 1% change in it, while the cost of transport and the international price of maize influence on the wholesale price in the state at levels of 0.21 and 0.13% for every unit percentage change in them.

En 2008, México figuraba como el segundo productor mundial (14.94%) de limones y el primero como exportador (20.5%), principalmente de limón persa, por lo que el objetivo de la investigación fue identificar y valorar aquellos factores que determinan la demanda de importaciones de limón persa en Estados Unidos, principal mercado destino (94.7%). Bajo el supuesto de que dicho mercado ofrece una capacidad real de expansión para los productores mexicanos de este cultivo, se formuló un modelo de regresión múltiple, considerando el ingreso, tipo de cambio (peso/dólar), precio unitario de importación y la demanda de importaciones,  estimado por el método de Mínimos Cuadrados Ordinarios (MCO); con datos anuales del  periodo 1994-2008, obteniendo también las elasticidades de la demanda. La variable de mayor  respuesta fue el ingreso con una elasticidad de  3.8, clasificando al limón persa como un bien normal superior; seguido del tipo de cambio  (0.83) y el precio (-0.666). Se concluyó, que es factible mantener el nivel de crecimiento actual de demanda de importaciones de limón persa, del 9.3% promedio anual, debido a que el incremento requerido en el ingreso real de Estados Unidos sería del 2.45% (ceteris paribus), contra el crecimiento observado del 2.9% en el periodo de estudio.

For aquaculture purposes, Macrobrachium tenellum is considered as a good candidate, is not aggressive nor presents cannibalism and can tolerate an ample interval of temperatures, salinities and oxygen concentrations. The present work evaluates the semi-intensive culture of M. tenellum under environmental conditions of summer and autumn with special attention to water temperature. The results of the experimental cultures in the tropical Mexican Pacific coast, suggest this species demonstrates better growth during the end of the spring, summer and the beginning of the autumn, time at which the average temperature of the water is near 30°C. The experimental cultures of end of autumn and beginnings of winter demonstrate minimum growth, with an average temperature of the culture water of 27°C.  Other parameters like pH, O2 concentration and turbidity in the culture water were similar in all the experimental cultures reason why temperature is suggested the factor was the determinant in the differences found in growth.  

In this work we adapted a protocol for the extraction of metagenomic DNA (ADNmg) bacteria in the digestive system (intestines, stomach and hepatopancreas) of Macrobrachium carcinus L., with reference to the method of extracting bacterial DNA from soils and sediments (Rojas-Herrera et al., 2008). This methodology consisted of enzymatic, physics, mechanics and chemistry after a series of tests was abolished enzymatic lysis. However, the success ADNmg extraction was influenced mainly by the preparation of the samples, in particular the hepatopancreas, where it was necessary to remove the fat by thermal shock temperature and phase separation by centrifugation with the sample frozen.The effectiveness of isolated DNA fragmentation was verified by gel electrophoresis in denaturing gradient (DGGE) after amplification with universal primers. In general, it had a low diversity (19 phylotypes) between the different organs analyzed of 13.5 ± 1 (intestines) to 11.7 ± 0.96 (stomach). The Shannon-Weaver index (2.45), Simpsons (10.88) and equity (0972) obtained from the digitization of the image of the gel, suggested that the phylotypes that form the gut microflora M. carcinus, is distributed unevenly between the different organs analyzed.

The effects of Moringa stenopetala leaf meal (MSLM) on nutrient intake and weight gain (WG) were evaluated. Forty unsexed Rhode Island Red chicks were randomly assigned to 4 treatment groups. The control diet (T1) (MSLM 0%), the experimental diets contained MSML at a rate of 2% (T2), 4% (T3), and 6% (T4) of the diets (as fed basis) to replace 3%, 5.9% and 8.8% of the crude protein (CP) of the control diet. Daily feed, dry matter and CP intake of the chicks fed MSLM diets were higher (p

The application of different diets have focused on seeking greater production in the ruminant animal feed varies, thus affecting rumen microbial population, however, the production efficiency of ruminants has been reported inconsistently. Furthermore, studies have been conducted secondary metabolites secreted by plants and has been having a function of attractant or repellent in plant-microbe interactions. So our goal is to integrate knowledge of rumen bacteria-particle interactions of forage used for food and flavonoids as stimulants in the flagellar movement. Thus, understanding the signaling pathways used by rumen bacteria to colonize food particles and degradation. Research and implement programs using genomic tools to help us discover chemotactic genes in rumen bacteria that contribute to elucidate principles governing the communication of microbial populations, their interactions and main products of microbial metabolism, and thus could raise the handling of ruminal fermentation, creating the probiotic cultures for cattle.