Fernando Casanova-Lugo

Influence of livestock systems with live fences of Gliricidia sepium on several soil properties in Tabasco, Mexico

The aim of the current study was to evaluate the effects of two livestock systems, a livestock system with live fences (LSLF) of Gliricidia sepium associated with signal grass ( Brachiaria decumbens ) and a livestock system based on a grass monoculture (LSPM), on specific physical and chemical soil characteristics at different depths and distances from the fence. In each system, we randomly selected 9 plots of 600 m 2 . A completely randomized design was used with a 2 x 3 factorial arrangement in which we analyzed the influence of the livestock systems (LSLF and LSPM), soil strata (0-10, 10-20 and 20-30 cm) and the interaction of both factors using a multivariate analysis of variance. In addition, we performed analysis of variance to determine the effect of distance sampling in the LSLF (0-3, 3-6 and 6-9 m). The LSLFs were associated with higher (P 0.05) at different depths and distances from the live fences. However, the soil pH varied between soil depths in the LSPM. Regarding the physical soil properties, only the sand and clay content varied (P 0.05). Sin embargo, pH del suelo vario entre las profundidades del suelo en los SGMP. En cuanto a las propiedades fisicas del suelo, solo las proporciones de arena y arcilla variaron a diferentes profundidades en ambos sistemas, pero no a diferentes distancias de los sistemas ganaderos con cercas vivas (P≤0.05). Se concluye que los SGCV tienen un enorme potencial para mejorar sustancialmente las propiedades fisicas y quimicas del suelo, siendo una oportunidad para frenar el deterioro de los suelos en sistemas de produccion ganaderos basados en el monocultivo de pasto.

Live fences reduce the diurnal and seasonal fluctuations of soil CO2 emissions in livestock systems

Deforestation of tropical forests for the establishment of grass monoculture for livestock production is responsible for about 30xa0% of CO2 emissions. This issue is particularly severe in degraded pastures because degraded soils favor CO2 flow to the soil surface. Silvopastoral systems could reduce CO2 emissions, notably by using live fences. Here, we hypothesized that live fences of Gliricidia sepium in livestock systems should reduce variations in environmental relative humidity and soil temperature and, in turn, reduce soil CO2 emissions. Here, we studied two livestock systems: (1) grass monoculture of Brachiaria decumbens with live fences of G. sepium and (2) grass monoculture of B. decumbens without live fences. We measured soil CO2 seasonal emissions at different times of the day, soil temperature, and environmental relative humidity. Nine 600-m2 plots were established in each system. All variables were measured over four 6-h period during a 24-h period, twice a month from April to September. Our results show that soil CO2 emissions showed less variability with G. septum live fences than without live fences. This lower variability is explained by the creation of a microclimate with a higher and more stable environmental relative humidity, provided by the shade of trees. Results also show, however, that global soil CO2 emissions did not differ between the two systems, with and without live fence. Moreover, soil CO2 emissions varied according to season, as shown by 1.082xa0g CO2 m−2xa0h−1 in the wet season versus 0.871xa0g CO2 m−2xa0h−1 in the dry season. Soil CO2 emissions varied also according to sampling time, as shown by 1.116xa0g CO 2 m−2xa0h−1 in the night versus 0.960 CO 2 m−2xa0h−1 in the morning.

Forage yield and quality of Leucaena leucocephala and Guazuma ulmifolia in mixed and pure fodder banks systems in Yucatan, Mexico

In tropical areas of Mexico, Leucaena leucocephala is widely used in silvopastoral systems. However, little information exists on other native woody species of high forage potential, such as Guazuma ulmifolia. The aim of this study was to evaluate the components of biomass, forage yield and quality, and availability of N in fodder banks of L. leucocephala, G. ulmifolia, and a mixture of both species during dry and rainy seasons, under sub-humid tropical conditions. The experimental unit was a 5xa0×xa010xa0m plot, containing three rows with 2xa0m between rows; each row had 20 plant positions with 0.50xa0m between plants. Within each plant position there was either a single plant, in the case of pure-crop, or two plants, in the case of mixed of both species. A complete randomized block design with three repetitions was used. In both seasons, there were a significantly greater proportion of leaves in the G. ulmifolia fodder banks (71xa0%) and in mixed fodder banks (69xa0%) than in L. leucocephala fodder banks (64xa0%). Consequently, these systems had leaf-to-stem ratios of 2.4, 2.2 and 1.9, respectively. The forage yield of fodder banks was not influenced by season. The mixed fodder bank had greater forage yield (5.1xa0txa0DMxa0ha−1) than the L. leucocephala fodder bank (3.4xa0txa0DMxa0ha−1) in each season. Additionally, the mixed fodder bank accumulated more forage yield during the experimental period (10.2xa0txa0DMxa0ha−1xa0year−1) than G. ulmifolia (9.0xa0txa0DMxa0ha−1xa0year−1) or L. leucocephala (6.9xa0txa0DMxa0ha−1xa0year−1). The concentrations of CP, C and C:N were not influenced by season. Forage NDF and ADF concentrations were greater in the rainy season (476xa0gxa0kg−1xa0DM) compared with the dry season (325xa0gxa0kg−1xa0DM). Mixed fodder banks had the greatest N yield (185.9xa0kgxa0ha−1) and consequently the greatest availability of N (371.8xa0kgxa0Nxa0ha−1xa0year−1). We conclude that mixed fodder banks of L. leucocephala and G. ulmifolia are a better option for improving productivity and forage quality in comparison with pure fodder banks in Yucatan, Mexico.

Carbon storage in livestock systems with and without live fences of Gliricidia sepium in the humid tropics of Mexico

Agroforestry systems (AFS) play a major role in the sequestration of carbon (C). The objectives of this study were to quantify the organic C stocks in the above- and below-ground tree biomass and in the soil in a cattle-farming system with live fences (CFSLF) of Gliricidia sepium and to compare the levels with those of a cattle-farming system based on a grass monoculture (CFSGM). The methodology included a forest inventory in nine randomly assigned plots and the destructive sampling of G. sepium 32 trees, measuring for each tree the diameter at breast height (DBH), stem height, total tree height, branch weight, leaf weight and coarse root weight. In addition, we measured grass biomass, collected litterfall and collected soil samples at depths of 0–10, 10–20 and 20–30xa0cm in the plots. A logarithmic model was developed to quantify the above- and below-ground tree biomass. The soil organic matter was determined by the dry combustion method. The total carbon stored in the CFSLF was 119.82xa0Mgxa0Cxa0ha−1, with the G. sepium trees contributing 5.7xa0% of the total C (6.48xa0Mgxa0Cxa0ha−1). The CFSGM stored 113.34xa0Mgxa0Cxa0ha−1. The grass biomass stored 15.32xa0Mgxa0Cxa0ha−1xa0year−1 in the CFSGM and 15.68xa0Mgxa0Cxa0ha−1xa0year−1 in the CFSLF, and the litterfall in the CFSLF stored 0.205xa0Mgxa0Cxa0ha−1xa0year−1. Despite the modest contribution of G. sepium trees to the C storage, the total carbon accumulated in the CFSLF and CFSGM was similar.

Carbon storage in a silvopastoral system compared to that in a deciduous dry forest in Michoacán, Mexico

Livestock production in the tropics contributes significantly to global greenhouse gas emissions, so better understanding the role of silvopastoral systems (SPS) in mitigating such emissions is necessary. The aim of this study was to evaluate the amounts of carbon stored in the biomass and soil organic carbon (SOC) components of a Leucaena leucocephala cum Panicum maximum silvopasture system (SPS) compared to a deciduous tropical forest (DTF), and a grass monoculture (GM) in Michoacán, Mexico. The above- and below-ground biomass were measured by destructive sampling in the SPS and GM, while previously reported allometric equations were used to quantify biomass stocks in the DTF. The SOC concentration up to 30xa0cm was determined by dry combustion method. The SPS and DTF contained more aboveground biomass (41.8u2009±u20093.30 and 36.7u2009±u20095.72xa0Mgxa0DMxa0ha−1) compared to GM (8.0u2009±u20090.76xa0Mgxa0DMxa0ha−1). However, the SPS exhibited greater belowground biomass (16.4u2009±u20091.95xa0Mgxa0DMxa0ha−1) than the other systems. The DTF had the highest SOC fraction in all depth classes with values ranging from 3.1u2009±u20090.07% to 3.7u2009±u20090.06%, respectively, compared to the other systems. The total carbon stocks in SPS was similar to DTF (120.7u2009±u200910.97 vs. 120.9u2009±u20096.38xa0Mgxa0Cxa0ha−1) but was significantly higher than GM (78.2u2009±u20098.41xa0Mgxa0Cxa0ha−1). In dry tropical conditions, SPS displays enormous potential for increasing biomass and soil carbon stocks compared to the GM and can thus be used as a greenhouse gas mitigation strategy in livestock production systems.

Relationship between body weight and body condition score with energy content in the carcass of Pelibuey ewes

ABSTRACT: The determination of energy content in the carcass and body of domestic animals by direct method involves very intensive work and it is costly. The aim of this study was to evaluate the relationship between body weight (BW) and body condition score (BCS) with the energy content of muscular and adipose tissues of adult Pelibuey ewes. Twenty two adult non-pregnant, nonlactating ewes of 35.63 ± 5.03 kg BW and 2.47±0.55 BCS were used. The correlation coefficients (r) of BCS between muscle energy (ME), fat energy (FE) and total energy (TE) were all significant (P<0.01) with values of 0.64, 0.66 and 0.69, respectively, while for BW between ME, FE and TE they were all significant (P<0.001) with values of 0.90, 0.76 and 0.89, respectively. The regression equations had high determination coefficients (r2) ranging from 0.87 to 0.94 when BCS was used as predictor, while using the BW the r2 ranged from 0.59 to 0.83. The inclusion of both BW and BCS in multiple regressions improved the prediction from 2 to 7%; nonetheless, the inclusion of BCS only was significant in the equation for TE. The use of BCS and BW in Pelibuey ewes provides a good estimate of the ME, TE and FE of the carcass.

Traditional uses of dispersed trees in the pastures of the mountainous region of Tabasco, Mexico

The rapid deforestation in the state of Tabasco due to extensive livestock farming has resulted in the decrease of the original forest cover. Only 4% of the original vegetation remains and that vegetation is concentrated in the mountainous regions of the state. This destructive process continues due to support by the current government livestock policies. Under these circumstances, the traditional silvopastoral systems of dispersed trees can present an option for reversing and mitigating deforestation practices. The objective of this study was to generate information on the tree species common to silvopastoral systems of dispersed trees in the pastures for two mountainous areas in Tabasco. In the study, 64 tree species, representing 26 plant families were identified. All species were characterized as multipurpose, with at least three reported uses and a maximum of seven for each species. In total, nine categories of local uses were identified for the trees. The main category of use was fuel (firewood), followed by timber and shade for the livestock. Although leguminous species (Fabaceae) were dominant, these species were utilized for uses other than the provision of fodder. Since 12 of the total species identified were recognized as sources of food for animals; the assumption that livestock farmers do not recognize the utility of these species for improving production yields is apparent. The results suggest that there is potential need to expand research and offer further education on the subject in Tabasco.

Diversity of Trees in the Mesoamerican Agroforestry System

Biodiversity conservation and production of foods imply a hard trade-off with no simple solutions routes. However, changing conventional agrarian and animal husbandry models to an agroforestry one is an important approach for achieving a better equilibrium between both economical and conservative goals. Agroforestry systems (AFS) for tropical lands provide a renewed old approach to deal with the need for feeding a growing population while avoiding damage to ecosystems on which food production is achieved. Neotropical studies on the subject have increased since the 1980s, accumulating evidences that it is possible to consider the potential of agroforestry to improve the status of biodiversity without hampering regular agricultural production. Three countries stand out for their contributions in the Mesoamerican region: Costa Rica, Mexico and Nicaragua. Notably, the researchers of biological diversity associated with Mesoamerican agroforestry systems have turned their attention primarily on nine biological groups: ants, bats, birds, butterflies, dung beetles, mammals, soil macrofauna, terrestrial mollusks and plants. Most research in Mesoamerica, including that in Colombia and Venezuela, dealing with biodiversity in the production systems has been abandoned. But there is an increasing trend of studies on biodiversity conservation in areas under active cultivation or livestock since both include trees. It is clear that the AFS can only help in reducing the negative impacts of agriculture and livestock grazing systems on the natural biodiversity. In conjunction with the network of protected areas in the region, this synergistic effect may increase the ability of biological conservation of the territory, alongside increasing economic benefits to the local rural society.