Development of Tropical Forages in Veracruz, Mexico: Agronomic Approach for the New Forage Legume Cratylia argentea

Pastures in the coast of the Gulf of Mexico are characterized by native species (Paspalum spp., Axonopus spp., etc.). These, are limited by productivity due to their low nutritional quality and poor persistence on grazing. The adaptation of new grass and legume species is essential to improve the productivity of animal production. An initial assessment should include the climatic and edaphic adaptation to the region. Species, such as Andropogon gayanus, Pueraria phaseoloides, Centrosema spp., Arachis pintoi, and Cratylia argentea, were evaluated, showing encouraging results compared to native species; our efforts were focused on C. argentea. Several research methods were applied to meet the objectives outlined for each experiment, including methodologies for the establishment of new species. All these trials were subject to rigorous experimental designs, and data were analyzed statistically, using the most adequate programs. These experiences allow us to visualize the most promising materials for the specific conditions of climate and soil. The potential results of this new forage species stand out. Also, these experiments allowed the development of new management practices to improve the productivity of the animal production systems of the region. C. argentea demonstrated its high forage value as a species suitable for silvopastoral systems

Rendimiento total de materia seca y calidad nutritiva de hojas y tallos jóvenes de cuatro accesiones de Cratylia argentea en el trópico húmedo de Veracruz, México

Se evaluaron cuatro accesiones de la leguminosa forrajera Cratylia argentea Ciat 18516, 18666, 18668 y 18676, durante un periodo de crecimiento ininterrumpido de 12 meses, para rendimiento de forraje de hojas (HO), tallos comestibles (TC), tallos no comestibles (TN) y calidad nutritiva de HO y TC, en el estado de Veracruz, México. Los rendimientos de forraje por componente de la planta fueron similares entre accesiones: 2580±212, 33±5 y 2444±233 kg MS/ha, para HO, TC y TN, respectivamente. Las accesiones fueron similares en proteína cruda (19.10%), fibra en detergente neutro (61.10%), fibra en detergente ácido (42.20%) y lignina (14.20%). La HO presentó más proteína cruda que TC, pero fue menor con respecto a ndf, adf, y mayor en lig. Para la desaparición in situ de la MS, las accesiones difirieron en la proporción del componente altamente soluble (a) de la materia seca, pero todos tuvieron tasas de degradación fraccional (c) y materia seca lentamente degradable (b), estadísticamente similares. La producción de gas in vitro del componente hoja fue la misma para todas las accesiones. Se concluyó que, en esta evaluación, las accesiones fueron similares entre ellas

Características de la vegetación en gramas nativas solas ó asociadas con Arachis pintoi CIAT 17434 en pastoreo rotacional intensivo

The objective of this study was to estimate some characteristics of pasture vegetation in native grass pastures alone (G) or associated with Arachis pintoi CIAT 17434 (GA) under intensive rotation in the humid tropics of Veracruz, five years after legume establishment. Five pasture divisions of G and three of GA were used. Samplings took place from 7/VIII/95 to 28/V/96, for a total of 27 for G and 18 for GA, the instantaneous stocking rates were 29.9±5.2 and 32.9±5.6 cows/ha/d and days of recovery were 43±4 and 50±4. There were no differences (P>0.05) between pastures for available dry matter, residual dry matter and dry matter intake, being the respective means: 29.3±2.0, 25.1±1.9 and 3.31±0.20 kg DM/100 kg LW. Pasture use in GA (18.5 ± 1.1 %) was greater (P0.05) by pastures, with means of 37.7 ± 8.1 kg DM/ha/d for the absolute and 0.0110 ± 0.0002 DM/kg/ha/d for the relative. Botanical composition was dominated by grasses in G and by A. pintoi in GA. The legume benefited the protein of forage but other variables were not improved.El objetivo de este ensayo fue estimar algunas características de la vegetación en pasturas de grama nativa sola (G) o asociada con Arachis pintoi CIAT 17434 (GA) sometidas a pastoreo rotacional intensivo en el trópico húmedo de Veracruz, luego de cinco años de haberse sembrado la leguminosa. Se usaron cinco divisiones de G y tres de GA. Los muestreos se efectuaron del 7/VIII/ 95 al 28/V/96, totalizando 27 para G y 18 para GA, las cargas animal instantáneas fueron 29.9±5.2 y 32.9±5.6 vacas/ha/día y los días de recuperación 43±4 y 50±4. No hubo diferencia entre pasturas (P>0.05) en cuanto a materia seca disponible, residual y el consumo, con promedios respectivos de 29.3 ± 2.0, 25.1 ± 1.9 y 3.31 ± 0.20 kg MS/100 kg PV. El nivel de uso de la pastura de GA (18.5±1.1 %) superó (

GROWTH CURVE OF A TROPICAL MIXED-GRASS PASTURE IN A HOT AND HUMID CLIMATE

Background. Pasture growth rate (PGR, kg/ha/day) depends on climatic and management practices. However, studies on the influence of the environment on pasture production and productivity of dry matter are scarce in tropical, hot, and humid regions of México. Objective. To estimate the pasture growth curve using time and climatic variables. Methodology. We related, through nonlinear models, the accumulated growth of a pasture composed of native grasses mixed with exotic grasses, using time and the variables temperature and day length as independent variables, the latter integrated into a single variable called thermal photo units (PTU). We estimated the daily growth rates of five divisions; from these, the forage yields for ten days until completing 29 periods. The best-fit models had the largest coefficients of determination and the lowest Akaike’s information criterion. Results. The model that best described the relationship between cumulative yield (Y) and cumulative growing days (X) was reciprocal-quadratic: y = x/(0.097535 – 0.0000881x + 0.0000006810x2) with R2Adj, of 0.9988 and an AICC of 222.6. The model that best described the relationship between the accumulated performance and the accumulated PTU was rational: y = (- 317.8 + 1.594x + 0.00001307x2)/(1 + 0.001059x + 0.00000001964x2), with R2Adjt.=0.9985 and AICC=233.4. Likewise, a two-segment model showed a close fit. The logarithmic model described the first segment: y1 = -2268 + 417.2*(ln(x)), when y2 =1079.3e0.00003932X, if x > 8415; with R2Adj. = 0.9975 and AICc = 245.1. The value 8415 PTU was when the first derivative of both models coincided. Implications. The information generated is useful because it allows grazing system adjustment concerning the correct stocking rate application and designing more efficient grazing rotations. Conclusions. The conversion of growth rates to accumulated yield for ten-day periods produced a smooth curve that allowed fitting high-precision nonlinear models to predict forage accumulation from time and climatic variables