Adoption of \u3ci\u3eBrachiaria\u3c/i\u3e Grasses in Mexico and Central America: A Successful Story

In Latin America and the Caribbean (LAC) there has been a major effort to develop new pastures technologies, to increase livestock productivity for the extensive systems prevailing in the tropical lowlands. This multi-national and inter-institutional effort was initiated through the International Network for the Evaluation of Tropical Pastures (RIEPT, by its name in Spanish), which operated from 1976 to 1996 under CIAT leadership. This network became a platform for institutions to train technicians, share forage material from existing gene banks, study the behaviour of new germplasm under different environments, and established the exchange of scientific information to extrapolate research results (Toledo, 1982). Six hundred and forty five agronomists from 24 countries in LAC were trained by RIEPT, in subjects related to forage agronomy and pasture evaluation. Training was key for the success of RIEPT, because these professionals carried out evaluations of new and improved forages under contrasting ecosystems and provided feedback. In addition, during this period participating institutions in RIEPT released 11 selected grasses as commercial cultivars, most of them from the Brachiaria genus, as well as 16 forage legume cultivars (CIAT, 2003). In Central America and Mexico these cultivars were released between 1990 and 1996. Forage evaluation activities in this region continues at present through a joint research agenda between CIAT and ILRI, as well as between CIAT and the private seed sector. Of all pasture cultivars released; grasses from the Brachiaria genus currently dominate the market – accounting for approximately 84% of all grass seed sales in Mexico and Honduras, 90% in Nicaragua, 85% in Costa Rica, and 97% in Panama during the last 5 years (Holmann et al., 2004). The objective of this paper is to estimate the impact of the adoption of Brachiaria grasses released through RIEPT during the period 1990-2003 on milk and beef production and to describe how this was achieved

Estimation and comparison of benefits due to feeding hay and silage during the dry season on commercial dual-purpose cattle production systems in Honduras and Costa Rica

Smallholders with dual-purpose cattle production systems in most Central America experience a shortage of forages during the dry season (4-8 month. As a result, substantially lower milk production and weight gain occurs. Dual-purpose operations seeking to maximize milk and beef production in the dry season can produce and feed hay or silage to their livestock. The increase in milk and beef production due to feeding hay or silage during the dry season on commercial dual-purpose cattle productions systems, the production costs of making silage or hay and the benefits as a result of feeding silage or hay are estimated and compared in Honduras and Costa Rica. Due to feeding silage or hay, farmers in Honduras and Costa Rica have increased milk production during the dry season. The costs of feeding hay are lower in both countries, although farmers feed a higher amount (kg DM/cow/ day) than silage. Feeding silage or hay to milking cows is profitable in both countries. The income-cost ratio and the net benefit ($/ cow/day) due to feeding these feedstuffs are positive. Farmers with milking cows in Honduras realise a higher income-cost ratio and net benefit due to feeding silage and hay than farmers in Costa Rica. Likewise, beef cows or young livestock supplemented with these feeding alternatives don't loose weight during the dry season. In Honduras as well in Costa Rica, it is profitable to feed silage or hay to beef cows or young livestock. Currently, no silage and a small hay market exist in Honduras. Possibly, these will develop due to an increasing demand for these profitable feedstuffs. In Costa Rica thanks to the efforts of agricultural organisations, a hay market of different qualities is developing

On the accuracy of language trees

Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic) features or characters for many different languages. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve it.Comment: 36 pages, 14 figure

Electrostatic boundary value problems in the Schwarzschild background

The electrostatic potential of any test charge distribution in Schwarzschild space with boundary values is derived. We calculate the Green's function, generalize the second Green's identity for p-forms and find the general solution. Boundary value problems are solved. With a multipole expansion the asymptotic property for the field of any charge distribution is derived. It is shown that one produces a Reissner--Nordstrom black hole if one lowers a test charge distribution slowly toward the horizon. The symmetry of the distribution is not important. All the multipole moments fade away except the monopole. A calculation of the gravitationally induced electrostatic self-force on a pointlike test charge distribution held stationary outside the black hole is presented.Comment: 18 pages, no figures, uses iopart.st

Low cost feeding strategies for dual purpose cattle in Venezuela

This simulation study was to evaluate low cost feeding strategies in response to higher cost of commercial concentrates to maintain current milk sales from dual purpose cattle herds in the humid lowlands of western Venezuela. Data were from farm surveys in 1987 and 1988. Baseline net margins from milk and beef per cow per year were $132 and$99 for two farm cases with average dally milk of 10 and 7 kg/cow and grazing mature forage supplemented with commercial concentrate. Alternative diets were 1) improving forage quality by more intensive grazing; 2) replacing commercial concentrate with a mixture of cassava tuber (Manihot esculenta), urea, and molasses and 3) supplementing grazing with a mixture of molasses and urea. Alternatively priced feeding strategies were compared by partial budgeting. Using less mature forage was .always more profitable than mature grass. Feeding molasses and urea with mature forage increased profits at least $64/cow on the high milk yield farm and$44/cow on the low milk yield farm compared with feeding commercial concentrate. The most costly cassava mixture with mature forage increased annual profit over the baseline diet at least $11/ cow on the high milk yield farm and by$22/cow on the low yield farm. Efficient use of existing feed resources may enhance economical livestock production in the humid lowlands of Venezuela

Differential Forms on Log Canonical Spaces

The present paper is concerned with differential forms on log canonical varieties. It is shown that any p-form defined on the smooth locus of a variety with canonical or klt singularities extends regularly to any resolution of singularities. In fact, a much more general theorem for log canonical pairs is established. The proof relies on vanishing theorems for log canonical varieties and on methods of the minimal model program. In addition, a theory of differential forms on dlt pairs is developed. It is shown that many of the fundamental theorems and techniques known for sheaves of logarithmic differentials on smooth varieties also hold in the dlt setting. Immediate applications include the existence of a pull-back map for reflexive differentials, generalisations of Bogomolov-Sommese type vanishing results, and a positive answer to the Lipman-Zariski conjecture for klt spaces.Comment: 72 pages, 6 figures. A shortened version of this paper has appeared in Publications math\'ematiques de l'IH\'ES. The final publication is available at http://www.springerlink.co

Arachis pintoi in the Humid Tropics of Colombia: A Forage Legume Success Story

Cattle liveweight gain and milk yield can be depressed significantly on grass alone pastures that degrade over time on the margins of tropical forest. Use of legumes in pastures is an alternative to minimize declines in quality and quantity of forage biomass and thus increase livestock production. From 1987-90, forage researchers in CIAT collaborated with several institutions in the Piedmont region of the Amazon basin in Caqueta, Colombia on selection of forage germplasm adapted to acid soils and with potential to reclaim large areas of degraded pastures in cattle farms of the region. The most successful pasture was the legume/ grass association of Arachis pintoi grown with several Brachiaria species. However, livestock producers in the region were not adopting the Arachis technology mainly because of lack of promotion, little knowledge on benefits and high seed cost. Thus, an inter-institutional on-farm project involving public and private institutions was carried out to document the on-farm benefits of Arachis-based pastures, train personnel of different institutions on establishment and utilization of Arachis pastures using participatory methods and initiate and catalyse an active extension transfer mechanism of the Arachis technology in the region