Tropical Legumes Research Articles

Responses of selected tropical forage legumes to imposed drought

Drought tolerance is an important attribute for the establishment of forage legumes in the rangelands of the seasonal semi-arid tropics. This experiment examined the seedling rooting depth, plant biomass, and other growth parameters of 5 perennial tropical legumes in response to different watering and drying regimes. Centrosema brasilianum cv. Oolloo and Macroptilium bracteatum (CPI 55770) produced deeper roots, greater root biomass, and more root nodules than Stylosanthes scabra cv. Seca and Desmanthus virgatus (CPI 79653), however only D. virgatus produced deeper roots and increased biomass in response to the drought treatment. Arachis triseminalis (CPI 91423), C. brasilianum and M. bracteatum flowered during the 9-week course of the experiment, with the latter two species producing pods. Seca, A. triseminalis and D. virgatus show adaptations of drought-tolerance, whilst C. brasilianum and M. bracteatum are adapted to drought avoidance.

Comparative Anti Inflammatory Activity of Hexane and Aqueous Extract of Mucuna pruriens

Introduction: Mucuna pruriens is a tropical legume native to Africa and tropical Asia. The plant is an annual climbing shrub with long vines that can reach a height of 15 meters in length. Mucuna pruriens belong to the family legume. It is a herbal drug that is used as a medicine for the treatment of male infertility, nervous disorder, and also as an aphrodisiac. It has been shown that it potentially has more medical importance. It causes orange hair that causes a severe itch when in contact with the skin. It releases a protein called mucanain.
 Aim: To determine the anti-inflammatory activity of aqueous and hexane extract of Mucuna pruriens.
 Materials and Methodology: The extract was prepared and the anti-inflammatory effect was done using a UV-Beckmann spectrometer. The anti-inflammatory activity of nanoparticles prepared using plant extract was investigated by albumin denaturation assay. The results of the test were described as the standard deviation and analyzed using UV-Vis spectroscopy. Correlation and analysis were done in SPSS.
 Results: The hexane solution and aqueous solution of Mucuna pruriens have a high percentage of inhibition at the 30 μl, 40 μl and 50 μl concentration when compared with a standard solution. And hexane has a high percentage of inhibition at 50μl when compared with a standard solution. The obtained data were analyzed using spearman correlation analysis and the non-parametric correlation was statistically significant at p value< 0.05.
 Conclusion: The aqueous and hexane extract of Mucuna pruriens show good anti- inflammatory activity. In that hexane extract has good anti-inflammatory activity when compared with aqueous extract. And it is used for disease. And further research should be done with the action and mechanism of Mucuna pruriens.

Differential expressions and enzymatic properties of malate dehydrogenases in response to nutrient and metal stresses in Stylosanthes guianensis

Malate dehydrogenase (MDH, EC 1.1.1.37) is a key enzyme that catalyzes a reversible NAD-dependent dehydrogenase reaction from oxaloacetate (OAA) to malate. Although MDH has been documented to participate in cellular metabolism and redox homeostasis in plants, the roles of MDH members in the tropical legume Stylosanthes guianensis (stylo) remain less definitive. In this study, except SgMDH1 that had been previously characterized, six novel MDH genes were isolated from stylo and were then designated as SgMDH2 to SgMDH7. All of the SgMDH proteins possessed the common features of NAD binding, dimerization interface and substrate binding sites. Expression analysis showed that three SgMDHs exhibited preferential expressions in leaves, and one SgMDH was mainly expressed in roots. Furthermore, SgMDHs were regulated by nutrient deficiencies in stylo roots, especially for phosphorus (-P) and potassium (-K) deficiencies. Differential responses of SgMDHs to trace metal stress and heavy metal toxicity were observed in stylo roots, suggesting the involvement of SgMDHs in the response of stylo to metal stresses. The six novel SgMDHs were subsequently expressed and purified from Escherichia coli to analyze their biochemical properties. Although SgMDHs exhibited variations in subcellular localizations, each SgMDH protein displayed a high level of catalytic efficiency towards OAA and NADH but a low level of catalytic efficiency towards malate and NAD+. In addition, the activities of recombinant SgMDH proteins were pH-dependent and temperature-sensitive, and exhibited differential regulations by various metal ions. These results together suggest the potential roles of SgMDHs in stylo coping with nutrient and metal stresses.

Effects of ensiling length and storage temperature on the nutritive value and fibre-bound protein of three tropical legumes ensiled alone or combined with sorghum

Changes in the nutritive value of forages are imminent under different ensiling conditions. Thus, a study was conducted to assess the effects of ensiling length and storage temperature on the nutritive value, fermentation characteristics and fibre-bound protein of three tropical forage legumes, sorghum and mixtures of sorghum and the legumes. Soybean (Glycine max), jack bean (Cannavalia ensiformis), lablab (Lablab purpureus) and sorghum (Sorghum bicolor) were solely grown and harvested, and the legumes were wilted before ensiling. Mixtures of sorghum and each legume were handmade on a percentage fresh weight basis of 60:40. Each forage and mixtures (400 g) were ensiled in polythene vacuum bags with homofermentative lactic acid bacteria inoculation for 30, 75 and 180 days. A set of mini silos were stored indoors, and another batch was stored outdoors. HOBO Pro v2 data loggers were deployed to monitor the ambient temperature of the storage locations during the entire ensiling period (from day 0–180). Measurements included nutrient analysis, fermentation quality and fibre bound protein characteristics. The hourly ambient temperature for outdoor and indoor storage ranged from 16° to 61°C vs 18–35 °C, respectively. Proximate constituents of all silages were influenced by ensiling length. Significant changes were primarily detected in fermentation products of legume silages between 30 and 75 d of ensiling. There were reduced fermentation products for silages stored outdoors. The ensiling length influenced proportions of neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) with outdoor silages resulting in a higher proportion of NDIN and ADIN compared to indoor silages. Overall, a short period of ensiling preserves the nutritional quality of ensiled forages compared to prolonged storage at high ambient temperatures typical of the tropics that increase nutrient losses. Thus, changes in the nutritional composition of forages during ensiling should be considered during ration formulations.

Unexpected high retention of 15 N-labeled nitrogen in a tropical legume forest under long-term nitrogen enrichment.

The responses of forests to nitrogen (N) deposition largely depend on the fates of deposited N within the ecosystem. Nitrogen-fixing legume trees widely occur in terrestrial forests, but the fates of deposited N in legume-dominated forests remain unclear, which limit a global evaluation of N deposition impacts and feedbacks on carbon sequestration. Here, we performed the first ecosystem-scale 15 N labeling experiment in a typical legume-dominated forest as well as in a nearby non-legume forest to determine the fates of N deposition between two different forest types and to explore their underlying mechanisms. The 15 N was sprayed bimonthly for 1year to the forest floor in control and N addition (50kgNha-1 year-1 for 10years) plots in both forests. We unexpectedly found a strong capacity of the legume forest to retain deposited N, with 75 ± 5% labeled N recovered in plants and soils, which was higher than that in the non-legume forest (56±4%). The higher 15 N recovery in legume forest was mainly driven by uptake by the legume trees, in which 15 N recovery was approximately 15% more than that in the nearby non-legume trees. This indicates higher N-demand by the legume than non-legume trees. Mineral soil was the major sink for deposited N, with 39±4% and 34±3% labeled N retained in the legume and non-legume forests, respectively. Moreover, N addition did not significantly change the 15 N recovery patterns of both forests. Overall, these findings indicate that legume-dominated forests act as a strong sink for deposited N regardless of high soil N availability under long-term atmospheric N deposition, which suggest a necessity to incorporate legume-dominated forests into N-cycling models of Earth systems to improve the understanding and prediction of terrestrial N budgets and the global N deposition effects.

Rumen degradation properties of tropical legumes feed under in sacco studies

Degradation properties of protein feed sources such as tropical legumes is very important to match with microbial protein synthesis and by pass protein requirements in dairy cattle ration formulation. However, the information is still limited. This study aims to determine the degradability of dry matter (DMD) and organic matter (OMD) from several legumes in Indonesia using in sacco method. There are 11 types of tropical legumes that are commonly used in dairy cattle ration have been studied, namely acacia, alfalfa, pterocarpus, gliricidia, indigofera, calliandra, butterfly leaf, leucaena, albizia, tamarind, and sesbania. The dried forage mesh samples were put into nylon bags and incubated in the rumen of two fistulated Friesian Holstein bulls for 0, 3, 6, 9, 12, 15, 24, 48, and 72 hours. Parameter observed were degradability of dry matter (DMD), and organic matter (OMD), kinetic parameters, and effective degradation. The data were analysed using descriptive statistic and regression from SAS University software. The result that sesbania and indigofera grouped into highly degradable forage (degradability > 80%), while acacia, albizia, calliandra grouped into low degradable forage (degradability < 50%). From this study it can be concluded that each type of legume has different degradability characteristics using in sacco method.

Are the interaction effects of warming and drought on nutritional status and biomass production in a tropical forage legume greater than their individual effects?

Drought alone and drought plus warming will change the nutrient requirements and biomass distributions of Stylosanthes capitata, while warming will be advantageous only under well-watered condition for the next decades. Climate change effects on natural and managed ecosystems are difficult to predict due to its multi-factor nature. However, most studies that investigate the impacts of climate change factors on plants, such as warming or drought, were conducted under one single stress and controlled environments. In this study, we evaluated the effects of elevated temperature (+ 2°C) (T) under different conditions of soil water availability (W) to understand the interactive effects of both factors on leaf, stem, and inflorescence macro and micronutrients concentration and biomass allocation of a tropical forage species, Stylosanthes capitata Vogel under field conditions. Temperature control was performed by a temperature free-air controlled enhancement (T-FACE) system. We observed that warming changed nutrient concentrations and plant growth depending on soil moisture levels, but the responses were specific for each plant organ. In general, we found that warming under well-watered conditions greatly improved nutrient concentration and biomass production, whilst the opposite effect was observed under non-irrigated and non-warmed conditions. However, under warmed and non-irrigated conditions, leaf biomass and leaf nutrient concentration were greatly reduced when compared to non-warmed and irrigated plants. Our findings suggest that warming (2°C above ambient temperature) and drought, as well as both combined stresses, will change the nutrient requirements and biomass distributions between plant aerial organs of S. capitata in tropical ecosystems, which may impact animal feeding in the future.

Estimating the proportion of in situ rumen-undegraded crude protein from chemical crude protein and fiber fractions in tropical forage grasses and legumes

Advanced methods exist to estimate dietary crude protein (CP) degradation in the rumen from the concentrations and/or proportions of chemical nutrient fractions. These methods have been developed primarily for feeds in temperate climates. Therefore, their accuracy and precision to predict proportions of rumen-undegraded CP (RUP) in tropical forages is uncertain. The objectives of the present study were (1) to assess the accuracy and precision of the estimates of in situ RUP proportions from CP fractions using established algorithms, and (2) to identify chemical nutrient fractions that accurately and precisely predict RUP proportions of tropical forages. The proximate nutrients, CP and fiber fractions of 23 unconserved forage grasses and 15 forage legumes commonly used as feeds for ruminants in the Tropics and Subtropics were analyzed. Their RUP proportions were determined at ruminal passage rates (Kp) of 2%, 5%, and 8%/hour using the in situ method (i. e., reference) and were also estimated from the analysis of the CP and fiber fractions using established equations. The RUP proportions determined with the in situ and the chemical method were evaluated using error index and dimensionless parameters. The nutritional composition variables that can predict RUP proportions of tropical forages (proximate nutrients, fiber, and CP fractions and their ratios) were selected using stepwise multiple linear regression models. The CP concentrations of our sample set ranged from 46 to 212 g/kg dry matter with in situ RUP proportions from 73 to 596 g/kg CP across all Kp. Previously established equations could not predict accurately and precisely RUP proportions of all forages. The concentrations of CP and fiber fractions and Kp were able to predict the proportion of RUP estimated in situ for tropical forages at Kp of 2%, 5%, and 8%/hour with an adjusted coefficient of determination ranging from 0.79 to 0.82 and a root mean square error ranging from 13% to 15% of the mean in situ RUP proportion. While equations established for temperate forages either over- or underestimate RUP proportions, algorithms developed in the present study might allow for an accurate and precise prediction of RUP proportions in forages commonly used in ruminant feeding in the Tropics and Subtropics.

Short phases of tropical forage legumes increase production of subsequent cereal crops in the seasonally dry tropics of eastern Indonesia

In temperate systems, it is well known that forage legumes can improve both nitrogen (N) supply and yields of subsequent cereal crops. While this is assumed to be true in tropical systems, it is less well tested, particularly in smallholder settings where forage is often cut and removed from the field. This paper confirms the potential of short phases of tropical forage legumes to provide N to subsequent crops in seasonally dry tropical farming systems. Across five experiments, maize and rice grain yields increased by up to 80 % after 4−8 month rotations of forage legumes, but the benefits were smaller when legume growth was reduced, biomass was removed for forage, or the yield potential of cereal crops was lower. We found that the additional N cycling from legumes can last for at least 2 years, although the benefit diminishes with time. When all legume material was retained as mulch, the estimated additional N provided to subsequent no-till maize crops was the equivalent of 9−15 kg urea-N per tonne of above-ground legume biomass produced but fell to 1.5−3 kg urea-N/t if forage was removed. After shoot removal, more legume N cycled to a subsequent rice crop (equivalent of 11–13 kg urea-N/t of legume biomass) than to a no-till maize crop, presumably because more below-ground material mineralised. Of the legumes tested, Clitoria ternatea grew best across a variety of environments and use patterns and provided the largest yield benefits to subsequent crops. This research demonstrates the potential to integrate short phases of tropical herbaceous forage legumes into smallholder crop-livestock systems in the seasonally dry tropics, and, in doing so, improve or maintain staple grain crop production and household food self-sufficiency.

Physiological responses and transcriptomic changes reveal the mechanisms underlying adaptation of Stylosanthes guianensis to phosphorus deficiency

BackgroundPhosphorus (P) is an essential macronutrient for plant growth that participates in a series of biological processes. Thus, P deficiency limits crop growth and yield. Although Stylosanthes guianensis (stylo) is an important tropical legume that displays adaptation to low phosphate (Pi) availability, its adaptive mechanisms remain largely unknown.ResultsIn this study, differences in low-P stress tolerance were investigated using two stylo cultivars (‘RY2’ and ‘RY5’) that were grown in hydroponics. Results showed that cultivar RY2 was better adapted to Pi starvation than RY5, as reflected by lower values of relative decrease rates of growth parameters than RY5 at low-P stress, especially for the reduction of shoot and root dry weight. Furthermore, RY2 exhibited higher P acquisition efficiency than RY5 under the same P treatment, although P utilization efficiency was similar between the two cultivars. In addition, better root growth performance and higher leaf and root APase activities were observed with RY2 compared to RY5. Subsequent RNA-seq analysis revealed 8,348 genes that were differentially expressed under P deficient and sufficient conditions in RY2 roots, with many Pi starvation regulated genes associated with P metabolic process, protein modification process, transport and other metabolic processes. A group of differentially expressed genes (DEGs) involved in Pi uptake and Pi homeostasis were identified, such as genes encoding Pi transporter (PT), purple acid phosphatase (PAP), and multidrug and toxin extrusion (MATE). Furthermore, a variety of genes related to transcription factors and regulators involved in Pi signaling, including genes belonging to the PHOSPHATE STARVATION RESPONSE 1-like (PHR1), WRKY and the SYG1/PHO81/XPR1 (SPX) domain, were also regulated by P deficiency in stylo roots.ConclusionsThis study reveals the possible mechanisms underlying the adaptation of stylo to P deficiency. The low-P tolerance in stylo is probably manifested through regulation of root growth, Pi acquisition and cellular Pi homeostasis as well as Pi signaling pathway. The identified genes involved in low-P tolerance can be potentially used to design the breeding strategy for developing P-efficient stylo cultivars to grow on acid soils in the tropics.

Sunn hemp planting date effect on growth, biomass accumulation, and nutritive value in southeastern Wyoming

AbstractSustainablesuccess of the Northern High Plains (NHP) crop and livestock industry is limited by market accessibility, infertile soils, short growing seasons, and availability of high nutritive value, low‐cost feed. Adoption of the tropical legume, Crotalaria juncea L. (commonly known as sunn hemp), into NHP cropping systems could improve the sustainability of the rotation by fitting into summer growing windows and being used as a hay alternative. Rainfed and irrigated studies were conducted in Lingle, WY, to determine the target planting date for sunn hemp in the NHP. Later planting day of year was correlated with increased percent establishment in the rainfed study but had no effect in the irrigated study. In both irrigated and rainfed studies, planting between 8 June and 18 June maximized biomass accumulation. Biomass accumulation 60 d after planting ranged from 0.2 to 5.1 Mg ha–1 in the rainfed study and 1.2 to 4.2 Mg ha–1 in the irrigated study. For both irrigated and rainfed studies, the nutritive value of sunn hemp was high with crude protein greater than 220 g Kg–1, acid detergent fiber less than 305 g Kg–1, neutral detergent fiber less than 331 g Kg–1, relative feed values above 183, and total digestible nutrients greater than 590 g Kg–1. Planting date did not affect nutritive value. Sunn hemp grown in the NHP has a 60‐d yield potential 5.1 Mg ha–1, should be planted between 8–18 June to 60‐d biomass production, and has nutritive value equivalent to supreme quality alfalfa (Medicago sativa L.) hay.

Creating delicious plant‐based products

Creating delicious plant‐based products

Replacement of alfalfa hay for tropical legumes in goats diets / Substituição do feno de alfafa pelo de leguminosas tropicais em dietas de caprinos

The aim of this study was to evaluate the effect of alfalfa hay replacement by tropical legume hay on goat diets. Four diets were formulated using: 1) perennial soybean hay; 2) tropical kudzu; 3) macrotiloma and 4) alfalfa, in a roughage/concentrate ratio of 25/75. Eight castrated crossbred (Boer x Saanen) animals, with a mean weight of 17.8 kg (4 months of age), were arranged in a 4 x 4 double Latin Square Design. Intake of dry matter (DM), organic matter (OM), crude protein (CP), total carbohydrates (TC), ether extract (EE), non-fibrous carbohydrates (NFC) and total digestible nutrients (TDN) were not affected by the legume species. On the other hand, the intake of acid detergent fiber (ADF) was lower in the diet formulated with alfalfa, compared to the other legumes (P&lt;0.05), since this presented lower levels in this diet. The digestibility of DM, OM, CP, ADF, TC and NFC did not differ among the four treatments (P&gt;0.05). However, EE digestibility was lower in the diet with alfalfa compared to ration with tropical kudzu and perennial soybeans. The digestibility of this constituent between the diet formulated with tropical kudzu and those formulated with macrotiloma and perennial soybean (P &lt; 0.05), and the digestibility of the NDF of the ration prepared with perennial soybean was higher than the other legumes. There was no difference for the nitrogen balance between the different diets, indicating that these legumes are options for replacement of alfalfa hay in goat diets.

Arbuscular mycorrhizal fungi to enhance the growth of tropical endangered species Pterocarpus indicus and Pericopsis mooniana in post gold mine field in Southeast Sulawesi, Indonesia

Abstract. Husna, Tuheteru FD, Arif A. 2021. Arbuscular mycorrhizal fungi to enhance the growth of tropical endangered species Pterocarpus indicus and Pericopsis mooniana in post gold mine field in Southeast Sulawesi, Indonesia. Biodiversitas 22: 3844-3853. Gold mining activities contribute to the national economy, but have a serious impact on forest and environmental degradation and pose a threat to tree species in the tropics. Reforestation of post-gold mining with tropical legume tree species is threatened with extinction. Arbuscular mycorrhizal fungi are effective in conservation of endangered plants and restoration of degraded land. The objective of the study was to evaluate the effect of native AM Fungi inoculation on the growth of Pterocarpus indicus and Pericopsis mooniana in nurseries and post-gold mining fields. P. indicus and P. mooniana seedlings were inoculated with Glomus claroideum Schenk &amp; Smith, Glomus coronatum Giovann., and mixed AMF (G. claroideum, G. coronatum). Uninoculated seedlings were used as control treatment, and they were maintained for 4 months under greenhouse conditions. After 4 months in greenhouse, seedlings were transferred to post-gold mine and planted for 4 months. The percentage of AMF colonization, plant growth, nutrient content and uptake of N, P, K, Fe, Mn were measured after 4 months both in the greenhouse and the field. The percentage of AMF colonization under greenhouse conditions in P. indicus and P. mooniana ranged 5.67-75.3% and 2.2-41.2%. All AMF colonization tended to have higher shoot height, leaf numbers and nodules, plant dry weight and N, P, K content under greenhouse conditions. Shoot height, stem diameter, leaf dry weight, N, P, K, Mn and Fe under field conditions had higher inoculated seedlings than control four months after planting. AMF could be used to conserve endangered tree species in post-gold mining reforestation in the tropics.

Anthelmintic‐like Activity of Leucaena leucocephala Aqueous Extract Against Gyrodactylus spp. in Naturally Infected Tilapia Fingerlings

AbstractAquaculture represents the fastest growing food‐producing sector worldwide. However, the intensification of fish farms has led to environmental, health, and welfare challenges. The monogenean ectoparasite Gyrodactylus spp. has been considered one of the most pathogenic ectoparasites affecting fish, and no specific control strategies besides formalin baths have been established. The use of bioactive plants has been recently proposed as an alternative method to control gyrodactylid infections. Leucaena leucocephala is a tropical legume that has been found with anthelmintic activity against both internal and external parasites of cattle. Therefore, the objective of this study was to assess the anthelmintic‐like activity of L. leucocephala aqueous extract against Gyrodactylus spp. in hybrid tilapia Oreochromis spp. fingerlings and its effect on host health through histopathological analysis. Five concentrations of L. leucocephala aqueous extract were employed (2.00, 1.00, 0.50, 0.25, and 0.125 mg/mL) to estimate the mean effective concentration (EC50). Distilled water and formalin (1:4,000) were used as negative and positive controls, respectively. The aqueous extract of L. leucocephala showed a dose‐dependent behavior, with an EC50 of 0.228 mg/mL. Quercetin was identified as the main phytochemical present in the extract. Postmortem analysis of fingerlings exposed to the plant extract had no treatment‐associated pathological findings, thus indicating that the use of L. leucocephala baths had no negative impact that could jeopardize the lives of treated animals. After the in vivo assessment, the aqueous extract of L. leucocephala appears to be a promising alternative to control gyrodactylid infection in tilapia.

Partitioning of Forage Mass and Nutritive Value in Sunn Hemp Leaf and Stem Components

Sunn hemp (SH; Crotalaria juncea L.) is a fast-growing, annual, warm-season tropical legume that could complement less productive cool-season forages such as tall fescue during summer. Little is known about seasonal forage mass and nutritive value partitioning in SH plant components when SH is managed for forage. We determined partitioning of forage mass and nutritive value (crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), acid detergent fiber (ADF), and neutral detergent fiber digestibility (NDFD)) concentrations in SH leaves and stems harvested 35, 45, and 55 days after planting (DAP) at Bradford Research Center, Columbia, MO, in a 2-year field study. Leaf and stem mass increased with increasing DAP and was greatest ( P ≤ 0.05 ) at 55 DAP followed by 45 and 35 DAP. Stems contributed most to the total forage mass beyond 45 DAP. Across years, CP was greatest ( P ≤ 0.05 ) in leaves (281 g kg−1 DM) and lowest for stems (81 g kg−1 DM) at 55 DAP. The lowest NDF ( P ≤ 0.05 ) was observed in leaves (251 g kg−1 DM) and stems (585 g kg−1 DM) at 35 DAP. Acid detergent fiber was lowest ( P ≤ 0.05 ) for SH leaves (178 g kg−1 DM) and stems (484 g kg−1 DM) at 35 DAP. Digestibility of leaves was greater than that of stems and generally decreased with maturity. The nutritive value of leaves was consistently greater than that of stems and decreased with maturity, except for CP of leaves, which was maintained throughout the season. Results suggested that SH leaves can maintain forage mass and greater quality than its stem throughout the growing season.

Mitigation of ruminal methane production with enhancing the fermentation by supplementation of different tropical forage legumes.

The aim of this research was to evaluate the influence of forage species adapted to the tropical region of Ecuador on gas production, enteric methane, digestion, and ruminal fermentation. The tree forage evaluated were C. arborea, E. fusca, B. forficata, E. poeppigiana, C. argentea, G. sepium, C. tora, and F. macrophylla. Ruminal fluid of four adult sheep fistulated with permanent cannulas in the rumen was used in the in vitro gas production technique. The in vitro gas production parameters were lower (P < 0.05) in the C. arborea (A = 41.68 mL gas/g DM, c = 0.044%/h and Lag = 1.654 h) and the average gas production rate for B. forficata was 1.017 mL/h (P < 0.05). C. arborea presented higher (P = 0.0001) effective degradation and real DM digestibility (40.461 g/kg and 82.51 mg/g, respectively). With respect to VFA, the highest (P < 0.05) proportion of acetic, propionic, and butyric was observed in C. arborea, G. sepium, and E. poeppigiana (72.52, 23.09, and 7.44 mol/100 mol, respectively) and the lowest (P = 0.0001) ratio: acetic/propionic was observed in G. sepium (2.92 mol/100 mol). The content of NH3-N (mg/L) showed no difference. The lowest (P = 0.0001) methane production was observed in C. arborea (1.23 mL CH4/g DM). The use of forage species of tropical climate rich in secondary metabolites in ruminant diets has the capacity to reduce the gas production and enteric methane; however, this is at the expense of the reduction of the fermentation of organic matter in the rumen.

Tropical grass and legume pastures may alter lamb meat physical and chemical characteristics.

The present study assessed the influence of the type of the tropical pastures on lamb body weight (BW) gain and meat quality. Fifty-four lambs were allocated to three grazing pastures: (1) AG - Aruana grass (Panicum maximum cv. IZ-5); (2) PP - pigeon pea legume (Cajanus cajan cv. Anão); and (3) CS - contiguous swards, half of the paddock with AG and half with PP. After 92days of grazing, the lambs were slaughtered. Carcasses were evaluated and the longissimus muscle was collected to determine color, lipid profile, tocopherol concentrations, and lipid oxidation. Although the pastures present differences in the characteristics of nutritional quality, the animals did not show difference in BW gain. The results show that all forage presented similar concentration of alpha-tocopherol (137 ± 14.37mgkg-1 of fresh matter), whereas total and condensed tannin contents were greater in PP, intermediate in CS, and the lowest in AG treatment (P = 0.0001). Meat α-tocopherol content was similar among treatments (P = 0.1392), with an average concentration close to the optimal level to reduce the meat oxidation. Meat from AG treatment had 45 and 25% lower n-6/n-3 ratio than meat from PP and CS treatments, respectively. The legume increases the unsaturated fatty acids and the grass can reduce the n6/n3 ratio. The level of condensed tannin concentration did show to have important effect on meat characteristics. Both tropical pastures studied can provide a high amount of alpha-tocopherol, generating a great potential to increase the concentration of this antioxidant in lamb's meat.

Elevated CO2 and warming affect pollen development in a tropical legume forage species

Global climate change is expected to have impacts on the physiological, phenological, and morphological traits of plants. However, the vulnerability of tropical plant reproductive processes in response to climate change events has been poorly studied. Here, we assess if warming and elevated CO2 compromise the pollen characteristics of Stylosanthes capitata Vogel, a tropical legume forage species. This work was conducted in a Trop-T-FACE (combined Free-Air Temperature Controlled Enhancement and Free-Air Carbon Dioxide Enrichment) facility, where we exposed the plants to four treatments: C (Control-ambient atmospheric carbon dioxide concentration [CO2] and ambient temperature); eCO2 (increase in [CO2] to 600 ppm and ambient temperature); eT (canopy temperature increase by 2°C and ambient [CO2]); and eCO2+eT, a combination of both treatments. We analyzed pollen morphology of samples taken from the different treatments through light microscopy (LM) and scanning electron microscopy (SEM). In addition, pollen viability was analyzed through colorimetry. Based on the histological LM analysis, the tapetum cells of pollen sacs showed early degeneration under eT (72%) added to hypertrophy under eCO2 (67%) and eCO2+eT (90%) treatments. SEM images showed compaction of pollen exine and less distinguishable pollen apertures in the treated plots (eCO2, eT, and eCO2+eT), possibly, by the early death of the tapetum cells. These morphological abnormalities may hinder the viability of pollen grains, as observed especially in the eCO2+eT treatment (%V=64%) that was the lowest in comparison with the Control (71%) and the other treatments (eCO2 = 69%, eT = 67%). These results indicate that during the reproductive cycle of S. capitata pollen sacs and pollen grains are vulnerable to warming, elevated CO2, and their combined effects.

Enteric methane emissions by young Brahman bulls grazing tropical pastures at different rainfall seasons in the Peruvian jungle.

The aim of this research was to measure enteric methane (CH4) emissions by young Brahman bulls grazing tropical pastures at different rainfall seasons in the Peruvian jungle. Fourteen 1.5-year-old, young bulls (280kg ± 18kg BW) were grazed on tropical grasses and legumes dominated by German grass [Echinochloa polystachya (Kunth) Hitch.] and minor proportion of Torourco grass [Paspalum conjugatum (P.J. Bergius) Roxb] and Leguminous Calopo (Calopogonium mucunoides Desv.) and Kudzú [Pueraria phaseoloides (Roxb.) Benth]. Enteric CH4 emission was measured by the sulfur hexafluoride (SF6) tracer-gas technique. Organic matter intake (OMI) was determined from organic matter digestibility (OMD) using a fecal protein crude index and fecal output estimated by the dosage of external markers. There was a difference in OMD between seasons (68 and 66% for the dry and rainy seasons, respectively; P < 0.0001). The OMI (6.7 and 7.4kg/day) and CH4 (178.7 and 298g/day) were higher (P < 0.05) in the dry season than in the rainy season, respectively. The yield of CH4 was lower (P < 0.0001) during rainy season (7.1%) than at the dry season (10.6%). The CH4 emission (g/day) was correlated with OMD (%) (r = 0.74, P < 0.0001). Enteric CH4 emissions of young bulls grazing mixtures of tropical pastures were significantly lower in animals grazing on the rainy-season, expressed either through unit of absolute emission, intake or as percentage of the GEI. Likewise, OMD of consumed pasture was the most important factor determining CH4 emission.