RESUMEN El objetivo del presente estudio fue determinar el valor nutritivo del forraje de mijo perla cosechado en diferentes estados fenológicos. El estudio se realizó en condiciones de riego con la variedad ICMV-221 de doble propósito, del que se tomaron muestras en cuatro estados fenológicos: H7) séptima hoja, HB) hoja bandera o última hoja, E) embuche y F) floración. Las muestras se analizaron por NIRS (near infrared spectroscopy) para determinar su contenido de nutrientes y los resultados se analizaron por medio de análisis de varianza dentro de un modelo completamente al azar. El contenido de materia orgánica se incrementó con la madurez (P<0.003), mientras que el contenido de proteína cruda fue mayor (P<0.005) en el estado de séptima hoja. El contenido de carbohidratos no fibrosos no mostró cambios significativos debidos a la edad de la planta (P>0.05), mientras el de fibra detergente neutra (FDN) fue similar (P>0.05) en los cuatro estados fenológicos y el de fibra detergente ácida (FDA) aumentó del estado de H7 al estado de F (P<0.008). El contenido de lignina (P<0.06) y el de lignina ligada a FDN (P<0.05) se elevaron con la edad. La digestibilidad de la materia seca disminuyó (P<0.0005) con la edad de 81.7 % en H7 a 69.0 % en F. Los contenidos de energía tendieron a reducirse con la madurez, aunque no en forma significativa (P>0.05). Se concluye que la edad del forraje de mijo perla al momento del corte afectó significativamente la mayoría de las variables de valor nutritivo estudiadas, siendo los forrajes más tiernos los que mostraron mejores características forrajeras. ABSTRACT The present study was conducted in order to evaluate the nutritive value of pearl millet forage harvested at different maturity states. The study was made under watering conditions with ICMV-221 two purposes variety. Four samples were taken at each four maturity states: (LS) leaf 7 th , (FL) flag leaf, (BS) boot stage, and (F) flowering. The samples were analyzed by NIRS (near infrared spectroscopy) to determine the nutrients content and results were subjected to analysis of variance into complete randomly model. Organic matter content increased with maturity (P<0.003), while crude protein content was higher (P<0.005) in LS. Non fiber carbohydrates did not show significant changes (P>0.05) with maturity. Neutral detergent fiber (NDF) content was similar (P>0.05) in the four maturity stages, but acid detergent fiber (ADF) content increased (P<0.008) from LS to F stage. Lignin and lignin linked to NDF increased (P<0.05) with age. Dry matter digestibility was reduced (P<0.0005) with age from 81.7 % in LS to 69.0 % in F stage. Energy contents tend to reduce with maturity of forage, but not significant differences were detected (P>0.05). Results indicated that age of pearl millet forage at harvest affected in a significant way almost all parameters of nutritive value. Younger forages showed the best nutritive characteristics.

The present study tested whether feeding ewes during the last third of pregnancy with cladodes of Opuntia (untreated or protein-enriched), as an alternative to alfalfa hay, would improve milk yield as well as the pre- and post-natal growth of their lambs. Sixty mature Rambouillet ewes and their progeny were randomly allocated among three nutritional treatments: (i) Control, fed alfalfa; (ii) Opuntia, fed untreated cladodes; (iii) E-Opuntia, fed protein-enriched cladodes (pre-treated with urea and ammonium sulphate). Birth weight did not differ among treatments (p > 0.05) but Control ewes produced more milk than both groups of Opuntia-fed ewes (p < 0.05). However, milk yield was not related to the growth of the progeny (p > 0.05) because lambs from E-Opuntia-fed ewes grew faster (p < 0.01) and were heavier at weaning (p < 0.05) than lambs from the other two groups. We conclude that Opuntia (with or without protein enrichment) can be used as an alternative to alfalfa hay for feeding ewes during the last third of pregnancy and therefore reduce production costs under extensive conditions in arid and semiarid regions. Moreover, protein-enriched Opuntia appears to improve postnatal lamb growth.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe nitrogen injection project in the Cantarell Complex, offshore Mexico, implemented in May 2000, has been the most ambitious pressure maintenance project around the world regarding incremental oil, production rate, nitrogen injection rate, and investment.In this paper, the main drivers and objectives of the project, along with key issues that have been taken into account to guaranty success, are reviewed. A description of the data acquisition program implemented to monitor reservoir performance during nitrogen injection is discussed and results analyzed.The pressure-production behavior of the reservoir during nitrogen injection is presented and results obtained after four years of operations are assessed, along with additional field development and benefits from updating and increasing facilities.

El pasto Llorón (Eragrostis curvula) es una gramínea perenne, originaria de Sudáfrica, de buen valor forrajero, se adapta bien a una amplia gama de suelos y condiciones climáticas. La variedad Imperial proviene de colectas realizadas en el centro y norte de México. Fue evaluada en zonas áridas y semiáridas, en temporal y riego desde 1986 hasta la obtención del registro en el año 2008. El registro otorgado por el Servicio Nacional de Inspección y Certificación de Semillas (SNICS) es: ERA-001-060608. A la fecha, la primera variedad registrada para esta especie en México. El rendimiento medio anual por hectárea de esta variedad oscila entre 896 y 1,947 kg de materia seca (MS) en condiciones de temporal, con una media de 1,200 kg y entre 3,150 y 6,100 kg MS en condiciones de riego con una media de 4,070 kg MS. Esta variedad de pasto es tolerante a la sequía, de fácil establecimiento y de rápido crecimiento, además es apetecible para el ganado, resistente al pastoreo y tolerante a la salinidad. Es una especie utilizada para la recuperación de agostaderos degradados y conservación de suelo en pastizales de zonas áridas y semiáridas en México.

A. Hernández, A. Bórquez, L. Alcaíno, J. Morales, P. Dantagnan, and P. Saez. 2010. Effects of autoclaving on the apparent digestibility coefficient of dehulled pea seed meal (Pisum sativum) in Rainbow trout (Oncorhynchus mykiss). Cien. Inv. Agr. 37(3): 39-46. The effect of autoclaving on the nutrients' apparent digestibility coefficient (ADC), digestible protein and energy of pea seed meal (P. sativum) fed to Rainbow trout (O. mykiss) was examined. Two samples of the pea meal were autoclaved at 121ºC and 1.1 atm for 5 min (5'APM) or 15 min (15'APM), respectively. A third sample, used as control, was not treated (RPM). One reference diet (Basal diet) and 3 experimental diets were elaborated and labelled based on autoclaving time applied to the ingredient (RPM, 5'APM and 15'APM). The four diets were assigned using a completely randomised design, with each treatment having three replicates. 12 tanks were stocked each with 15 trouts with an average weight of 235 ± 10.4 g. Faeces were collected over a 7-day period using a settlement column and pooled within the tank. ADCs were determined using chromium oxide (Cr 2 O 3 ) as an inert digestibility indicator. No significant differences (P>0.05) regarding protein ADC were found among all treatments. On the other hand, dry matter, energy and nitrogen free extract (NFE) ADC showed significant differences (p<0.05) among all the different treatments. Results showed that 5'APM improved dry matter, protein, and energy ADC of the dehulled pea seed meal in diets for rainbow trout.

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Tillandsia recurvata (Linnaeus) Linnaeus is an epiphyte that causes damage or death in trees. It is possible that the ruminant animals under extensive conditions can contribute to its control. The aim of the study was to determine the chemical and mineral value of Tillandsia recurvata (TR). An experiment was conducted at three different ecological environments during the four different seasons of the year in San Luis Potosi, Mexico. In each ecological environment, four samples of TR grown in mesquite trees (Prosopis spp.) were taken at four different season of the year to determine chemical content. Additionally, one more sample was taken to determine mineral content. Both the ecological environment and the season of the year affected (P<.001) the chemical and mineral content. However, according to the analyses, some mineral levels seem to be high and might compromise the health and consequently the animal production. In conclusion, TR has nutritional and mineral characteristics to be considered as a potential food source for ruminants at any time of the year. However, further research is needed to elucidate if TR can be included in the diet of ruminants in northern Mexico without compromising the health and the production.

RESUMENunder irrigation conditions. These varieties of grass are tolerant to drought, easy settlement and rapid growth; they are also appealing for livestock, grazing-resistant and tolerant to salinity. Currently, is the specie most used in the rehabilitation and conservation of soil in grassland of arid and semi-arid zones in Mexico.