Agronomic Evaluation of Twenty Ecotypes of \u3cem\u3eLeucaena\u3c/em\u3e spp. for Acid Soil Conditions in México

Leucaena leucocephala Lam. (de Witt) has been shown to be a good forage producer and to posses good persistence under grazing conditions in México tolerating well the management of local cattlemen (Quero et al., 2004). The Leucaena genus is native to Central America and Mexico (Hughes, 1998), but L. leucocephala is a low producer under acid soil conditions. The natural diversity is a good source of resistance to acid soil conditions resistance and to other adverse factors. Several Leucaena accessions were evaluated for production under acid soil conditions in tropical Mexico

Plant Biomass and Bovine Live Weight Changes in Mono-Specific and Mixed Pastures during the Rainy Season in Dry Tropical Mexico

Dry tropics suffer long drought periods each year, negatively affecting the amount and digestibility of forage for cattle production. The aim of this study was evaluate different pasture types, grazed by cattle during the rainy season. Three hectares were prepared to compare: grass monoculture, Andropogon gayanus (G); a grass-legume mixture of A. gayanus and Clitoria ternatea (GL), and a grass-legume-tree mixture of A. gayanus, C. ternatea and Morus alba (GLT). Two grazing cycles (4 d grazing followed by 32 d resting; 72 d total) were completed. Three heifers (average initial weight 192 kg) grazed each experimental unit. The amounts of forage offered, remaining after grazing, and removed by animals differed significantly among the pasture treatments. Total forage offered by period was 2007, 4089, and 4192 DM kg/ha for G, GL, and GLT, respectively. Total residual forage was 1074, 1878 and 2613 DM kg/ha respectively, while total forage removed was 934, 2209, and 1579 DM kg/ha, respectively. Differences for offered forage were detected only for residual and consumed forage for GL prairies. Differences in available forage were mainly due to differences in the amount of stem and live material. Daily weight gain was 0.138, 0.504 and 0.501 kg per animal for G, GL, and GLT, respectively. Mixed pasture treatments yielded better live weight gain due to the better quality of available forage

Forage Biomass and Bovine Live Weight Changes within Monospecific and Mixed Prairies over the Dry Season in Tropical México

In the tropical systems of cattle grazing, the limited period of forage production and low forage protein content and digestibility of the same, are the main constraints to increasing live weight gain. Grass-legume pasture improves forage quantity and quality and sowing mixed swards in both the wet and dry tropics is now common practice. However, much less is known if inclusion of a fodder tree as a third component could further improve forage parameters. The aim of this study was to evaluate three types of grasslands, grazed by cattle in the dry season of the dry tropics. Swards were established to compare: grass only (PP), grass-legume (PA) and silvo-pastoral (PSP) pastures on basis of forage on-offer, residual and disappeared and bullock’s daily live-weight gain. Species used were: Andropogon gayanus Kunth, Clitoria ternatea Linn and Morus alba Linn

\u3cem\u3eHymenachne Amplexicaluis\u3c/em\u3e [(Rudge) Nees] Genetic Resources Collection in México, a Suitable Grass for Flood Plains in Tropical Areas

Hymenachne amplexicaluis [( Rudge ) Nees; 2n= 2x= 24; Azuche, West Indian marsh grass] is a native Central and South America C3 grass that grows well under intermittent flooding conditions. It produces good seed set and stolons to thrive on new areas assuring its survival, combined with an efficient N metabolism to promote vigorous new growing leaves and tillers (Antel et al., 1998). Azuche is a dual attribute species when introduced to new areas; it has valuable forage attributes but also is a potential weed (Hill, 2000). As Azuche is a native species, one must deal with in the best possible way within Tropical Latin America areas (Enríquez et al., 2004). No report has been found to date on living genetic resources collection and evaluation for this species

Nutritional Sensitivity Per Morphological Component in \u3ci\u3eUrochloa\u3c/i\u3e Hybrid under Tropical Environments

Camello® (GP 3025) is a tolerant to drought Urochloa hybrid grass showing good forage production, early flowering with high regrowth rates. The objective was to define nutrient concentration changes by morphological component and, their differences for two tropical contrasting environments. Nutrient concentrations differences (P≤0.05) were observed among morphological components over time. In environments (Aw1) the morphological components showed higher average protein content in comparison to that from hostile conditions (Aw0); lamina (12.2% vs 10.4%), pseudostem (9.5% vs 6.6%) and sheath (9.8% vs 6.8%). Hostile environments (Aw0) promoted increases for FAD (47.9%, 46.9%, pseudostem and sheath, respectively) and lignin (6.6%, 9.1% pseudostem and sheath, respectively). The nutritional changes per morphological components is the best tool to define optimal moment for harvesting on nutritional bioavailability for livestock production intensification

Effect of Grazing Management on Herbage Accumulation of Lucerne-Orchard Grass Sward

Throughout most of México, lucerne (Medicago sativa) is the primary forage legume used in the dairy industry. Unfortunately, lucerne does not grow in late autumn and winter due to adverse weather. Recent studies with lucerne have suggested that the inclusion of a companion grass will invariably increase the seasonal distribution and total annual yield of swards (Laidlaw & Teuber, 2001). However the management of mixed swards containing lucerne is difficult as a grazing frequency or intensity which suits one species may be detrimental to the other. Changes in balance between grass and legume, especially in grazed swards, have been observed. In México mixtures of lucerne-orchard grass have a good persistence and productivity. However the explanation for this is unclear. This study examined the effects of different grazing management practices on lucerne-orchard grass production and seasonal distribution

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum