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Background. The productive variability of the forage is determined by the type of soil and the cultivation system. The use of silvopastoral systems represents an alternative because they can increase forage production and quality. Objective. To evaluate the production, the morphological components and the nutritional quality of the biomass of Cynodon plectostachyus (star grass) alone or in association with Leucaena leucocephala (huaxin). Methodology. The study was carried out in Tizimin, Yucatan, Mexico. Plots of C. plectostachyus were established in alleys croping of L. leucocephala and in monoculture, in hyperskeletal Luvisols and Leptosols soils. A 2 X 2 factorial design with five repetitions per treatment was used. The biomass production, the forage components and the content of crude protein and neutral detergent fiber were evaluated for one year. Results. Forage production, leaf and forage quality did not change according to the cultivation system (p≥0.05). No effect is believed due to the type of soil (p≥0.05). The interaction of the cultivation system with the type of soil increased the NDF content of C. plectostachyus (p≤0.05). Implications. The association of C. plectostachyus and L. leucocephala could increase the availability of structural carbohydrates for ruminant nutrition. Likewise, it is essential to consider long-term evaluations that allow to know the improvements in the crude protein content and the biomass production of the grasses in association under silvopastoral systems. Conclusions. The association of C. plectostachyus with L. leucocephala in Leptosol soil increases the availability of structural carbohydrates by increasing the stem and dead tissue that can be incorporated as organic matter in the soil.

Background: The global community has recognized silvopastoral systems (SPS) as an alternative to contribute to the resolution of various socio-environmental problems derived from extensive livestock farming, deforestation, climate change and the current pandemic derived from SARS-CoV-2. Its technical and social viability has motivated various sectors of society to promote its massification or scaling. However, although there are important advances in agroforestry and silvopastoral scientific research in southeastern Mexico, there are no works that address the experiences of massification of silvopastoral systems. Objective: The objective of this study was to identify the experiences of massification of various projects of SSP, the participation of social actors and the barriers and trade-offs in their implementation in the state of Chiapas (Mexico). Methodology: The study considered an analysis period from 2000 to 2020. A review of scientific and technical documents was made, various social actors were interviewed (livestock producers, technicians from international and national development agencies, technicians and advisers from peasant organizations, technicians from non-governmental organizations, academics from research centers and universities) who have promoted SPS and good livestock practices in Chiapas. Two participatory workshops were held. Results. A timeline was built and five relevant experiences of massification of SPS in various agroecological regions of Chiapas were analyzed: a) Scolel Té Project, b) Puyacatengo Agreement (Red Selva), c) Sustainable Rural Development Project in Biological Corridors , d) Innovative mechanisms for a cooperation program towards adaptation to climate change in the Sierra Madre and Costa de Chiapas, e) Early Action Initiatives for Mitigation in livestock areas (IAT-REDD +) and e) Agrosilvopastoral Biodiversity and Livestock Landscapes Project Sustainable (BioPaSOS). Various socio-environmental barriers and alliances between multiple social actors are shown. Implications: The work makes a contribution to the historicity of the massification processes of SPS and to the process of change in livestock. It is necessary to continue with an in-depth analysis of the social and technological impact that the various massification initiatives shown have had. Conclusions: The massification process that occurred between the years of study has shown the importance of alliances between various social sectors (producers-development agencies-academia-Governments), which has allowed the transition from local projects to projects with broad territorial coverage.

El objetivo del estudio fue determinar la cantidad óptima de alimento y peso del cerdo pelón mexicano (CPM) que se asocie a la máxima ganancia. Se utilizó la información de 22 hembras de CPM con un peso inicial de 5.07 ± 1.43 kg y final de 95.62 ± 12.09 kg; el ciclo de engorda se dividió en cuatro etapas. Para determinar los óptimos de consumo de alimento, peso y edad de venta del animal se empleó una función de producción representada por un modelo polinomial cuadrático; se consideraron precios de venta de 30.00, 35.00, 40.00 y $45.00 por kg de PV con alimentación 100% alimento balanceado y otro con restricción de 18%. En las etapas I y II se registró la mayor eficiencia alimenticia con 0.37 y 0.30 kg de ganancia por kg de alimento. El producto marginal promedio fue decreciente (0.24, 0.23, 0.21 y 0.15 por kg de alimento para las etapas I, II, III y IV). El peso óptimo de mercado se incrementó en el mismo sentido que el precio de venta del animal siendo: 15.50 a 75.00 kg en la alimentación de 100% alimento balanceado y 46.70 a 86.80 kg en la restringida. Debido al bajo valor de los parámetros obtenidos hacen necesaria la integración de la actividad primaria como parte de la cadena productiva con la finalidad de obtener la máxima ganancia y conservación de dicho recurso zoogenético.

Pods of Samanea saman have been reported to be effective in mitigating methane (CH4) emissions in ruminants. The aim of this study was to evaluate the effect of inclusion of S. saman pod meal in the ration on feed intake, apparent digestibility, rumen fermentation, rumen degradation, protozoa population, and enteric CH4 emissions in crossbred heifers fed low-quality tropical grass. Four crossbred heifers (Bos taurus × B. indicus) with an average live weight (LW) of 261.5 ± 1.29 kg were used in a 4 × 4 Latin square design with four periods of 23 days (17 days for adaptation and 6 days for measurements of response variables). Levels of inclusion of S. saman ground pods in the ration were 0, 10, 20 and 30% of dry matter (DM). Enteric CH4 emissions were measured using open-circuit respiration chambers. Additionally, rumen degradation of the different components of S. saman pods was assessed. Incorporation of S. saman levels had no effect on dry matter intake (DMI) (P > .05), apparent digestibility of dry matter (DM) and organic matter (OM) (P > .05) nor protozoal count (P > .05). It was found that molar proportion of propionic acid in rumen liquid was increased (P

Ruminant animals contribute significantly to methane emissions in tropical regions. Nonetheless, there are few facilities available in those regions of the world for in vivo measurement of methane production in cattle. T he aim of the present work was to describe the design, construction and operation of respiration chambers for in vivo measurement of methane production in cattle in Mexico. Locally available materials were used in the construction. Walls, roof and doors were constructed of thermic panels with two windows of acrylic at the front so the animal can be observed at all times. Chambers have an air volume of 9.97 m 3 . Air is drawn from the chamber at a rate of 500 L/min by the effect of mass action flow generators. Methane was measured in air samples with an infrared analyzer. Chambers operate under a slight negative pressure of around -500 Pa. Air temperature inside the chambers is kept at 23 °C with an air conditioner, while relative humidity is maintained at 55 % with a dehumidifier. Functioning of the chambers was evaluated in Bos indicus , Nelore cattle fed Taiwan grass ( Pennisetum purpureum ) and a concentrate (18 % crude protein), and measurements were made during runs of 23 h duration. Methane production was on average 173.2 L per day, while the emission factor was 17.48 L methane per kilogram o dry matter consumed. It concludes that this respiration facility is capable of measuring methane production accurately in cattle fed tropical rations.