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The study was conducted to determine the effects of supplementing probiotics and concentrates on intake and growth performance of Sahelian does fed Brachiaria decumbens grass. Twenty-four Sahelian does averaging one year and weighing 13.3 ± 1.16 kg were assigned randomly in a 2 x 2 factorial arrangement to four treatments in a Completely Randomized Design with 6 replicates and used to measure intake and live weight changes for 14 weeks. The factors were levels of concentrate and probiotics. Blood samples were taken for the determination of haematological and biochemical parameters. The results revealed differences (P < 0.05) in total dry matter intake, live weight changes and feed conversion ratio attributable to treatment effects. The differences observed in total dry matter intake led to improvements in average daily gain, feed conversion ratio and growth rate. All blood haematological indices with the exception of mean cell volume were impacted positively by treatment effects. White blood cell and total protein contents improved linearly with probiotics and higher level of concentrate supplementation, while total cholesterol content declined (P < 0.05). The results highlighted the positive impact of probiotics and higher level of concentrate supplementation on growth performance and blood profile of growing Sahelian does on a basal diet of Brachiaria decumbens grass. [ABSTRACT FROM AUTHOR]

The main goal of this investigation was to determine the effects of Brachiaria decumbens leaf meal on the health performance, blood biomarkers, and relative telomere length of broiler chickens raised in tropical conditions. A total of 300, day-old, male, Ross 308 broilers were divided into six groups and given various feeding regimens based on a completely randomized design model. T1 commercial feed was devoid of antibiotics (negative control) whereas T2 commercial feed was supplemented with 100 mg/kg oxytetracycline (positive control). Commercial diets supplemented with 25, 50, 75, and 100 mg/kg of powdered B. decumbens leaf meal was given to the birds in treatments T3, T4, T5, and T6, respectively. Throughout the 42-day study, there were a few occurrences of leg problems, diarrhoea, and fatalities, but no statistical association was detected. The growth performance, leucocyte profile, immunoglobulin and cytokine concentrations, and relative telomere length, however, differed substantially among treatments. T3 broilers fed with diets supplemented with 25 mg/kg of B. decumbens leaf meal exhibited the best growth performance (highest final body weight and body weight gain; lowest cumulative feed conversion ratio), leucocyte profiling (increased total white blood cell count, monocytes, and basophil count; decreased heterophil to lymphocyte ratio), immunoglobulins (up-regulated IgG, IgA, and IgM), cytokines (increased IL4 and IL7), and telomere length. In conclusion, B. decumbens leaf meal can be used instead of antibiotics to enhance the growth and health of broilers raised in hot, humid conditions. [ABSTRACT FROM AUTHOR]

The humid tropics of Ecuador is a potential livestock production area. Urochloa spp. cultivars are a forage option in this region. Environmental and management conditions determine forage yield and nutritional value and should be researched prior to establishing new forage species. An evaluation was done of total dry matter yield (TDM; t ha-1), morphological components proportions (%; leaf, stem, dead material and inflorescence) and in situ dry matter digestibility (DMD; g kg-1)) in five Urochloa cultivars (Mulato II, Marandú, Xaraés, Piatá and Señal [control]) and at three regrowth ages (4, 6 and 8 wk) during the rainy and dry seasons. A completely randomized block design in a split plot arrangement was used to analyze the data by season. During the rainy season, TDM did not differ (P>0.05) between cultivars. In the dry season, Marandú had a lower yield than Xaraés (0.92 vs 1.21 t ha-1). Morphological component proportions differed between cultivars (P<0.05), although the leaves contributed the most overall to yield. From four to eight weeks, DMD decreased from 64 to 56 % in the rainy season and from 60 to 56 % in the dry season. The evaluated cultivars exhibited acceptable TDM yields (2.6 t ha-1 in rainy season, 1.0 t ha-1 in dry season) and DMD (602 g kg-1 in rainy season, 574 g kg-1 in dry season). They are adequate forage alternatives for livestock in the humid tropics of Ecuador. [ABSTRACT FROM AUTHOR]

It was hypothesized that i t is possible that inoculum from different ruminant specie s with different digesti ve abilities feeding from a certain forage may show different feed utilization s comparing to other ruminant specie s . Five Brachiaria grass es were evaluated : B . decumbens cv . Basilisk, B . decumbens access D70, B . humidicola cv . Tupi, B humidicola cv . Common, and B . ruziziensis access R124, at two regrowth ages (21 and 42 d) . Production, bromatological content, in vitro dry matter digestibility ( iv DMD ) and in vitro neutral detergent fiber digestibility ( iv NDFD ) were analyzed using bovine or ovine inoculums . The experiment use d a 5 × 2 × 2 factorial design and found significant effect s for grass variety and regrowth age . In addition, significant interaction s from grass × age on dry matter, crude protein, neutral detergent fiber and acid detergent fiber of total sample and leaf blade were found . There were significant effect of grass variety and grass age on forage mass, leaf blade / stem ratio, leaf blade, stem, senescent material and growth. I n vitro digestibility assays of inoculum source showed significant effect i n some varieties . Due to differences in in vitro assays, it was recommended t he use of specie s - specific inoculums for feed evaluations according to the animal it is intended for . Also, B. decumbens cv . Basilisk presented the best in vitro digestibility ( iv DMD and iv NDFD ) in bovine inoculum, whereas B. humidicola cv . Tupi had better in vitro digestibility ( iv DMD and iv N D FD) in ovine inoculum. [ABSTRACT FROM AUTHOR]

A simulated grazing was developed with Brachiaria decumbens cv. Basilisk, to study the performance of dairy cows during rainy season in two grazing intensities: T1 = 75 and T2 = 150 LAU ha-1 day-1. Twenty Siboney crossbred cows were studied, between the second and third lactation, with 480 ± 8 kg of body weight (10 animals treatment-1), grazing 15 hours a day. InfoStat statistical program, version 12.0, was used for data processing. T2 animals showed lower grass availability (P = 0.0072) and intake decrease (P = 0.0362) (24.35 vs. 17.57 and 12.77 vs. 11.33 kg DM animal-1 day-1 for availability and intake of animals of 75 and 150 LAU ha-1 day-1). No differences were reported in individual production per cow and dairy components. However, production per area increased (P = 0.0001) by 1.74 times in T2 with respect to T1 (3,279.99 and 5,722.71 kg of milk ha-1 rainy season-1, for T1 and T2, respectively). Production cost of a liter of milk increased by 11.8 % in the treatment with the lowest intensity (2.17 vs. 1.96 $ L-1, for 75 and 150 LAU ha-1 day-1). Results indicate that animals from the treatment with 150 LAU ha-1 day-1 showed no differences in individual production, although they increased productivity per grazing area by 2,842.72 L, and decreased costs by 0.21 $ produced L-1. [ABSTRACT FROM AUTHOR]

Tools that generate models with good biomass predictive capacity are essential to maintain the sustainability of production systems. The objective was to analyze the relationship between forage biomass and structural variables and generate models to predict total forage biomass (TFB) and green leaf blade biomass (GLB). Irrigated pastures of Brachiaria decumbens Stapf 'Basilisk' were kept under rotational stocking with sheep (Ovis aries L.) The TFB, GLB, leaf area index (LAI), height (cm), and normalized difference vegetation index (NDVI) were evaluated. The experimental design was completely randomized with four replicates: ten and five cycles of defoliation management, respectively, were used to generate and validate the stages of the models. The best goodness of fit was obtained by nonlinear models for both TFB and GLB, which can be confirmed by high Spearman's correlations and significance (P < 0.0001). The path analysis showed low collinearity (42.60) between NDVI, LAI, and height; the high determination coefficient (R²) with values of 0.8421 and 0.7767 demonstrated their associations with TFB and GLB, respectively. Among the studied models to predict TFB and GLB, only exponentials using NDVI and power using LAI and height showed the best fit. In the validation stage, the models related to height exhibited the highest performance with 0.9531 (TFB) and 0.9638 (GLB) d-index, -2.3 (TFB) and -7.20 (GLB) bias, and 0.8532 (TFB) and 0.8932 (GLB) R². Only nonlinear models using height (cm) to predict TFB and GLB had the best practical application potential, thus ensuring efficiency in data collection. [ABSTRACT FROM AUTHOR]

Soil tillage and cover crops impact spontaneous vegetation in agrosystems. Soil tillage destroys seedlings and can affect the soil seedbank. Cover crops compete with naturally occurring spontaneous species. Our aim was to gain insight into how soil tillage (here, the false seedbed technique) and cover crops impact the spontaneous vegetation in fallows preceding banana crops. In a fallowed field in Guadeloupe (French West Indies), two factors were combined in a split-plot design: the soil tillage modality before cover crop sowing (with or without the false seedbed technique) and the cover crop species (Crotalaria spectabilis, Pueraria phaseoloïdes, a 50/50 mix of Brachiaria decumbens + Brachiaria ruziziensis, a spontaneous vegetation control). On a monthly basis, in three permanent quadrats per sub-plot, all spontaneous species were identified and their numbers counted, while calculating the species richness and Shannon's diversity index. The spontaneous vegetation dynamics contrasted depending on the treatment. From 7 months post-sowing the species density, richness and Shannon index were significantly lower in treatments with B. decumbens + B. ruziziensis and P. phaseoloïdes, while in treatments with C. spectabilis, the species density and richness were significantly higher with than without the false seedbed technique. These effects were probably related to differences in the competitive ability of the cover crop used and, to a lesser extent, to the false seedbed effects on the soil seedbank. This is the first study to show that under a tropical climate, sown cover crop species combined with different soil tillage modalities have substantial impacts on the species density, richness and diversity of the spontaneous plant community over a 1-year period. These results could help farmers in their weed control strategies by providing them with a deeper understanding of the effects of practices on the spontaneous plant community. [ABSTRACT FROM AUTHOR]

Background: the use of creep-feeding combined with the correct management of pastures has been one of the main tools of nutritional management in cattle. Objective: to evaluate the effects of supplementation with different protein regimes on the metabolic profile in grazing suckling male calves. Methods: fifty suckling Nellore male calves with average initial body weight (BW) of 114 ± 2.4 kg and 105 ± 3.0 days age were used and distributed in a completely randomized design in two treatments and 25 replicates. The protein regimens evaluated were low protein (LOW)-supplement with 150 g CP/kg DM and; High protein (HIGH) - supplement with 300 g CP/kg DM. The supplements were composed of soybean meal‚ cornmeal‚ wheat meal‚ mineral mixture‚ and molasses‚ and provided in amounts of 6 g/kg BW. The animals were subjected to 78 experimental days and kept in eight 5 hectares paddocks each‚ formed by Brachiaria decumbens and equipped with drinkers and feeders. All animals had unrestricted access to water. Blood samples were collected to quantify levels of urea‚ albumin‚ globulins‚ total protein‚ glucose‚ triglycerides‚ and insulinlike growth factor 1 (IGF-1). Globulin concentrations were calculated by the difference between total protein and albumin concentration. Results: no treatment effect was observed (p > 0.10) on concentrations of glucose (77.6 vs 81.6 mg/mL)‚ triglycerides (32.8 vs 39.2 mg/mL)‚ total proteins (6.52 vs 6.67 g/dL)‚ globulin (3.28 vs 3.25 g/dL) and IGF-1 (424 vs 441 nm/ mL); while the albumin (3.24 vs 3.42 g/dL) and SUN (10.2 vs 15.7 mg/dL) concentrations did show significant differences (p < 0.05)‚ being higher in the calves supplemented with higher level of crude protein. Conclusions: supplementation with 150 g CP/kg DM in the amount of 6 g/kg PC is recommended for lactating beef calves during the rainy season and rainy-dry transition. [ABSTRACT FROM AUTHOR]

Background: to ensure continuous calves' growth, the supply of supplements is necessary to impact the animals' tissue response. Objective: the aim of this study was to evaluate the effects of supplementation with different protein regimens on performance in suckling beef calves. Methods: fifty suckling Nellore calves with average initial body weight (BW) of 114 ± 2.4 kg and 105 ± 3.0 days age were used and distributed in a completely randomized design with two supplementation treatments: Low protein (LOW) and High protein (HIGH). The supplements were composed of soybean meal, cornmeal, wheat meal, mineral mixture, and molasses, containing 150 g CP/kg dry matter (DM) and 300 g CP/kg DM for LOW and HIGH respectively, and provided in amounts of 6 g/kg BW. The animals underwent 78 experimental days, and were kept in eight 5 hectares paddocks each, formed by Brachiaria decumbens and equipped with drinkers and feeders. For productive performance evaluation, all calves were weighed at the beginning and end of the experiment after 14 h for solids fasting. Also, on the 78th-day experimental carcass images were obtained by ultrasound between the 12th and 13th ribs over the longissimus muscle to measure the ribeye area and backfatthickness on the Longissimus muscle (FAT-L), and between the ischium and pubis to the backfat-thickness on the rump (FAT-R). Biopsies of Longissimus dorsi muscle were performed at 75 days to measure the number and diameter of muscle fibers. Results: no difference (p > 0.05) was observed for average daily gain (LOW = 0.98 vs HIGH = 1.00 kg/d) or final BW (LOW = 191 vs HIGH = 193 kg) throughout the experiment. Likewise, no effect (p > 0.05) of the amounts of protein supplementation was verified on ribeye area (LOW = 36.7 vs HIGH = 38.8 cm2), FAT-L (LOW = 1.38 vs HIGH = 1.54 mm), FAT-R (LOW = 2.06 vs HIGH = 2.30 mm), or number (LOW = 141 vs HIGH = 142) and diameter (LOW = 29.2 vs HIGH = 30.9) of muscle fibers. Conclusions: supplementation with 150 g CP/kg DM in the amount of 6 g/kg BW is recommended for suckling beef calves in grazing. [ABSTRACT FROM AUTHOR]

The beneficial effects of feeding rabbits with forages have been recommended. However, limited study has been made on feeding values of locally available forages in rabbits. Therefore, an experiment was conducted to evaluate the effect of Asyastasia gangetica and Brachiaria decunbens on intake, digestibility, and growth performance of rabbits. Twelve rabbits were distributed into three diets: (i) 100% commercial pellet as control (T1), (ii) 50% pellet plus Asyastasia gangetica ad libitum (T2), and (iii) 50% pellet plus Brachiaria decumbens ad libitum (T3). Daily feed intake, nutrient digestibility, weekly body weight, and feed conversion ratio (FCR) were measured. Intakes of total dry matter (DM) (121.2-134.3 g/d) and organic matter (OM) (115.1-132.5 g/d) were similar (p>0.05) for all the groups. The crude protein (CP) intake of rabbits fed with T1 (10.1 g/d) and T3 (9.6 g/d) diets was similar (p>0.05), but lower (p<0.05) than T2 (14.1 g/d) diet. Ether extract intake of rabbits fed with T2 (2.9 g/d) and T3 (3.9 g/d) diets was similar (p>0.05), but lower (p<0.05) than T1 (5.1 g/d) diet. Neutral detergent fibre (NDF) intake was higher (p<0.05) for rabbits fed with T3 (55.8 g/d) diet followed by T2 (41.7 g/d) and T1 (31.7 g/d) diets. There were no differences (p>0.05) on the digestibilities of DM, OM, and CP among treatments. Total weight gain and daily weight gain were higher (p<0.05) for rabbits fed with T1 (568 and 11.0 g) and T2 (468 and 9.0 g) diets than T3 (155 and 3.3 g) diet, respectively. The lowest FCR was obtained with T1 (12.3) and T2 (13.9) diets, whereas the highest was obtained with T3 (30.3) diet. In conclusion, diet containing Asyastasia gangetica showed more benefits in terms of CP and NDF intakes, weight gain and FCR than the diet containing Brachiaria decumbens. A combination of concentrate and Asyastasia gangetica is recommended as a partial replacement for concentrate in rabbit production. [ABSTRACT FROM AUTHOR]

Identifying forage species that are responsive in regions with marked water deficits is one of the greatest challenges for the sustainable development of agriculture. However, information is still lacking about the persistence response of those pastures and their abilities to produce new tissues at the times of water scarcity. We hypothesized that Brachiaria grass has a tillering capacity during water-stress periods. This study thus examined the tillering capacity and structural characteristics of four Brachiaria brizantha cultivars (Xaraés, Piatã, Marandu, and Paiaguás) and one Brachiaria decumbens cultivar (Basilisk) in the Brazilian semi-arid region during the dry season (September to March). The experiment was laid out in a randomized block design with repeated measures over time in which five treatments were tested in four replicates. Tillering parameters, pasture production, and structural variables were evaluated. There was no interaction effect of cultivar × evaluation period on the tiller appearance (p= 0.1774), mortality (p= 0.1952) or survival (p= 0.4469) rates. The highest tiller appearance and mortality rates were observed in Marandu, while the highest survival rates were found in Marandu and Paiaguás. The index of tiller population stability was higher than or equal to 1.0 in all cultivars. Cultivar Basilisk showed the highest herbage mass yield (4448.0 kg DM ha-1), whereas Basilisk exhibited the highest yields of leaf (1845.9 kg DM ha-1), stem (1676.9 kg DM ha-1), and dead material (925.2 kg DM ha-1). The highest leaf:stem ratio (1.8) was found in Marandu. Cultivar Xaraés had the highest canopy (70.8 cm). The B. brizantha and B. decumbens cultivars evaluated in this study have the potential for cultivation in areas with marked water deficits, as is the case of the Brazilian semi-arid region. Cultivars Marandu, Basilisk, and Paiaguás exhibited the greatest tillering dynamics as well as the highest herbage-mass yield. [ABSTRACT FROM AUTHOR]

This research was aimed at studying the in vitro ruminal biohydrogenation (BH) of C18 fatty acids (FA) in mixtures of Indigofera zollingeriana and Brachiaria decumbens. Four combinations of experimental rations of I. zollingeriana : B. decumbens were tested i.e., IZ 1 (45%:45%), IZ 2 (60%:30%), IZ 3 (75%:15%), and IZ 4 (90%:0%). The remaining 10% in in each ration was rice bran. The experimental design was based on a completely randomized design with five replicates. Results revealed that there was a statistically significant difference (P<0.01) in the composition of C18 unsaturated FA (UFA) and saturated FA (SFA) for each in vitro incubation period of 1, 2, 4, 8 and 24 h. The highest accumulation of C18 UFA at 24 h was observed in the incubation of IZ 4 (19.87%). The BH of C18:3, C18:2, and C18:1 showed no differences (P>0.05). Composition of C18:0 after incubation showed a significant difference (P<0.01) with the lowest composition was observed in IZ 2 (22%). In conclusion, combination of I. zollingeriana and B. decumbens at different ratio has minor inhibition effect on BH of C18 UFA. [ABSTRACT FROM AUTHOR]

Introduction: Due to its current coverage, the root biomass of tropical pastures is of vital importance for the terrestrial carbon storage, but its estimation has been mainly indirect and with a very wide range of values. Objective: To document at national and global level as well as compare, the root carbon stocks extracted directly from two grasslands of different growth type and origin. Methods: The biomass and root carbon stocks were directly extracted from two tropical pastures with more than 40 yr of age. The biomass and total carbon, one native with stoloniferous growth (Paspalum notatum) and one introduced with growth in tillers (Urochloa decumbens) were measured. The study was conducted between August and October 2016. Three plots of 1 600 m2 each were selected per pasture, with 10 sub-squares (4 m2 each) in each plot to determine the floristic composition, aboveground biomass and C. The biomass and root C were estimated by hand in three trenches (1.50 m x 0.50 m x 1.0 m) per plot. The organic carbon content was determined with the ignition method at an average temperature of 550 °C for 3 hours. For the statistical analysis, a two-factor ANOVA was used, where one factor was the treatments that were the type of pasture (2) and the other factor was the section of the grass (above and belowground). Results: The floristic composition of the two types of pasture was different due to its management history. On average, 28.25 Mg ha-1 of total C was estimated for the locality. The native pasture of stoloniferous growth P. notatum yields almost three-fold more biomass (42.5 MgC ha-1) than the introduced with growth in tillers U. decumbens (14 MgC ha-1) due to the radicular storage (38.5 vs. 11.46 MgC ha-1). Seventy-four point five percent of the carbon in P. notatum was located in the radicular part and 25.5 % above-ground, while in U. decumbens 56.5 and 43.5 %, respectively. Conclusions: P. notatum accumulated more total and radicular biomass and carbon than U. decumbens. The best adaptation of the native grass as well as the morphology of its root system may explain this difference. Ninety six percent of the biomass and root C is found in the first 0.50 m depth. Due to the contribution of its radicular portion, tropical pastures can constitute important reservoirs of terrestrial carbon considering its extension nowadays. [ABSTRACT FROM AUTHOR]

The selection of sexual genitors in Urochloa decumbens breeding is dependent upon the performance of their progeny for several traits simultaneously. Thus, our objectives were to (i) compare the efficiency of indices to select genitors of U. decumbens, (ii) evaluate the genetic gains obtained through selection intensities, and (iii) evaluate the multivariate pattern of progenies through principal components analysis (PCA). For this purpose, 1415 hybrids from 75 progenies of full siblings were evaluated at Embrapa Beef Cattle (Brazil) using seven cuts for dry matter production, regrowth, protein, fiber, lignin, and percentage digestibility. Statistical analyses were performed using mixed models and PCA. The direct selection for dry matter production provided a 37.51% genetic gain. Agronomic traits using indices provided greater gains. Genitors selected using PCA Biplot were similar to selections using indices. Indices and PCA were proven to be an excellent tool to select multi-traits in U. decumbens. [ABSTRACT FROM AUTHOR]

Brachiaria decumbens (signal grass) is a highly productive tropical grass that is widespread in some tropical countries due to its adaptation to a wide range of environments and soil types. However, a limiting factor for the use of this grass is its toxicity from steroidal saponins. Sporadic outbreaks of hepatogenous photosensitization in ruminants grazing on this grass have been reported. Sheep are more susceptible than other animal species and the young are more susceptible than adults. This review article will critically shed light on the B. decumbens profile, its toxic compounds, mechanisms, clinical responses, blood profile alterations, pathological changes, and acute phase responses related to signal grass intoxication. Further research is needed to integrate new findings on B. decumbens intoxication with previous preventive and therapeutic trials to minimize or remove its deleterious toxic effect. [ABSTRACT FROM AUTHOR]

Biochar has been used as an amendment for disturbed soils. However, the changes of the rhizobacterial community after the biochar addition in mine soils, has not yet been elucidated. The aim of this study was to evaluate the response in the rhizobacterial communities of Brachiaria decumbens during different reclamation processes of coal mining using biochar. Five treatments were carried out: control, mine soil + biochar, mine soil + biochar + Azospirillum brasilense, mine soil + biochar + arbuscular mycorrhizal fungal + Mortierella sp. DNA from the rhizospheric soil was sequenced by Ion Torrent. The relative abundance in each sample was calculated. The Proteobacteria (70%) and Actinobacteria (23%) phyla dominated the rhizobacterial community composition during the establishment time. Seven months after seeding, Actinobacteria decreased significantly, while Proteobacteria increased. The Acidobacteria phylum was higher in the control. There was a higher abundance of Proteobacteria with the biochar treatments than for the control, thus the baseline for the rhizobacterial community changes induced by biochar was provided. The alpha diversity index showed the effect of biochar on the diversity and dominance of the rhizobacterial communities. The hierarchical clustering tree showed a correlation between the treatments with biochar, and a significant differentiation between these and the control treatment. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the control and susceptibility of signalgrass and ruzigrass in initial growth under different rates of glyphosate and fluazifop-p-butil. The treatments were distributed in a 2 × 6 factorial design, with five repetitions, being two grasses: Brachiaria decumbens cv. Basilisk (signalgrass) and B. ruziziensis (ruzigrass) with six doses of herbicides: 0.00; 0.25; 0.50; 1.00; 1.5 and 2.00 times the commercial dose recommended by manufacturers. At 7, 15, 21, and 30 days after herbicide application (DAA) were evaluated the intoxication in signalgrass and ruzigrass, visually. The glyphosate toxicity was of 100% in both plants, signalgrass and ruzigrass, even at the lowest dose (90 g ha-1), so it can control effectively these species in early growth stage. It was observed that the plants exposed to fluazifop-p-butil showed regrowth only in the doses to 100 g ha-1 and 50 g ha-1 for signalgrass and ruzigrass, respectively. These results confirm the effectiveness of this herbicide molecule in the control of these two species from doses of 200 g ha-1 and 100 g ha-1 for signal grass and ruzigrass, respectively. [ABSTRACT FROM AUTHOR]

Abstract The potential of the symbiosis between plants and arbuscular mycorrhizal fungi (AMF) to reduce emissions of the greenhouse gas N 2 O has gained scientific attention in the last years. Given the high nitrogen (N) requirements of AMF and their role in plant N uptake, they may reduce the availability of mineral N that could be subject to N 2 O emissions and leaching losses. We investigated the impact of AMF on the growth of tropical grass Brachiaria decumbens Stapf. and on N 2 O released after fertilization with urea in a mesocosm study. To evaluate the role of nitrification in N 2 O emissions, we used nitrification inhibitor dicyandiamide (DCD). The study included a full-factorial design (n = 6) with two AMF treatments (with and without AMF inoculation) and three fertilization treatments (control, urea and urea + DCD), applied after 92 days of growth. Plant growth, soil properties and N 2 O emissions were measured during the following 2 weeks and the abundance of nitrifiers was quantified one and two weeks after fertilization. The production of N 2 O increased after urea application but only without DCD, indicating the importance of nitrification in N 2 O emissions. The emissions of N 2 O after urea application were reduced by 46% due to the presence of AMF. Nevertheless, the abundance of ammonia-oxidizing bacteria (AOB) was increased by urea and AMF, while plant growth was reduced by the AMF. The increased root:shoot ratio of the biomass in AMF pots suggests competition between AMF and plants. This study demonstrated that immobilization of N by AMF can reduce N 2 O emissions after fertilization, even when plant growth is reduced. The inverse relationship between (higher) AOB abundance and (lower) nitrification rates suggests that changes in the activity of AOB, rather than abundance, may be indicative of the impact of the AMF- Brachiaria symbiosis on N cycling in tropical grasslands. Alternatively, the difference between N 2 O emissions from AMF and non-AMF pots may be explained by increased reduction of N 2 O in the presence of AMF. Longer-term studies are needed to verify whether the effects of AMF on N 2 O emissions and/or plant growth persist over time or are limited to initial immobilization of N by AMF in N-limited systems. Highlights • The impact of AMF on nitrous oxide emissions was assessed in a pot experiment. • AMF reduced the nitrous oxide emissions after fertilization with urea. • The abundance of AOB was increased by AMF. • Plant growth was reduced by AMF while MBN was increased. [ABSTRACT FROM AUTHOR]

Silvopastoral system (SPS) has been suggested to ensure sustainability in animal production systems in tropical ecosystems. The objective of this study was to evaluate the productive and nutritive value traits of Brachiaria decumbens and performance of dairy heifers in SPS and open pasture (OP) during the summer and autumn of two consecutive years in the SPS and OP (17th and 18th years after establishment). Experimental design was a randomized complete block with two treatments (SPS and OP) and three replications in subdivided plots with repeated measures in time. There was reduction in the tiller population density, total and green forage mass, and total and green forage bulk density in the SPS when compared to the OP in the summer. In the autumn, no difference was observed between the systems. Shading in SPS increased crude protein content of the grass pasture by 25% and 33% when compared to the OP during the first and second experimental years, respectively, and reduced neutral detergent fibre content. However, it did not change acid detergent fibre or lignin content. OP provided higher stocking rate and weight gain per area than the SPS. Average daily gain was higher in the OP in the second experimental year. Severe shading conditions should be avoided, because in the long‐term they may threaten the persistence and sustainability of pasture in the SPS. It is recommended to plant a low density of trees or implement management strategies of the tree component by either thinning or pruning over the years after planting. [ABSTRACT FROM AUTHOR]

Abstract The Llanos region of Colombia represents one of the last large agricultural frontiers and is undergoing a rapid conversion from naturalized savanna to intensive agriculture with high agrochemical inputs and tillage. This massive land-use conversion has considerable impact on ecosystem services and biodiversity, particularly soil macrofauna, yet the full implications of this land-use shift for long-term agroecosystem productivity are poorly understood. To better elucidate potential land-use change impacts on agricultural production we used experimental microcosms in the greenhouse to evaluate how the common earthworm, Pontoscolex corethrurus, influences plant growth, nutrient uptake, and key soil properties relative to the application of lime and P fertilizer, both common soil fertility amendments in the region. Additionally, we aimed to explore the potential for interactions between earthworms and these amendments across distinct plant types, the grass Brachiaria decumbens and the legume Phaseolus vulgaris , which display different rooting patterns and nutrient acquisition strategies. Earthworms increased the biomass production of B. decumbens by 180% and N uptake by more than 240%, while P fertilizers and lime additions increased total biomass by less than 30% each for B. decumbens. Effects on P. vulgaris were similar, but less pronounced with earthworms increasing total biomass production by 35% and total plant N content by 70%, while neither lime nor P alone significantly influenced total biomass or N uptake. However, a significant interaction between earthworms and lime enhanced total biomass N content of P. vulgaris by more than 150% relative to microcosms without P. corethrurus , suggesting that earthworms can greatly enhance the efficacy of lime in soils. Additionally, we found that earthworms greatly improved soil aggregation, but only in the presence of plants, and that this effect was most prominent in microcosms with P. vulgaris. When testing treatment effects on soil P availability, only fertilizer P additions significantly influenced resin P, but not microbial biomass P. Our findings suggests the importance of developing management strategies that promote the activity and diversity of earthworms and other soil biota as a means to enhance crop productivity, resource use efficiency and a range of soil-based ecosystem services in the Llanos region and beyond. Highlights • Earthworms enhance plant growth more than lime or P fertilizer. • Lime only improves plant N uptake in the presence of earthworms. • Earthworms enhance soil structure, but only in the presence of growing plants. • Farm management should consider soil biological communities to optimize resource use efficiency. [ABSTRACT FROM AUTHOR]

A simulated grazing system was developed, using a total of 2.66 hectares, established with the variety Brachiaria decumbens vc. Basilisk; with the objective of studying their performance under dry conditions and without fertilization, subjected to two grazing intensities (GI): GI1 = 75 and GI2 = 150 LAU ha-1 day-1, during the rainy period. It was worked with 20 crossbred Siboney dairy cows between the second and third lactation (10 animals treatment-1), the animals grazed 15 hours a day. The areas under study showed an increase (P <0.05) in the Brachiaria proportion, in 7.9 and 13.2 %, for 75 and 150 LAU ha-1 day-1, respectively. The areas subjected to the highest intensity, showed higher availability of DM ha-1 paddock-1 (P <0.01) in 39.9 % (1 831.05 vs 2 562.11 kg DM ha-1 rotation-1, for 75 and 150 LAU ha-1 day-1, respectively); likewise, the grass yield was favored (P <0.05) in 23.9 % when it was submitted to 150 LAU ha-1 day-1. There were not differences in the bromatological composition of the grass. The obtained results, under these conditions, show that the Basilisk grass variety, subjected to grazing intensity of 150 LAU ha-1 day-1, maintains higher stability and likewise showed higher availability and grass yield, not affecting the bromatological quality of it. [ABSTRACT FROM AUTHOR]

Highlights • Photosensitization in naive sheep grazing B. decumbens under full sunlight or silvopasture was evaluated. • B. decumbens is highly toxic to sheep not adapted to grazing (naïve). • Protodioscin content in B. decumbens was higher under full sunlight than in silvopasture. • Silvopasture shading does not prevent photosensitization in naive sheep grazing B. decumbens. Abstract The work consisted of the evaluation of photosensitization in sheep grazing signal grass (Brachiaria decumbens) in a silvopastoral system or under full sunlight for 60 days in the summer. We hypothesized that shade provided by trees in the silvopastoral system prevents or alleviates the classic symptoms of photosensitization in grazing sheep and affects the concentration of the saponin protodioscin in signal grass. Twenty naïve crossbred sheep (Dorper x Santa Ines) were used in a randomized block design, with two blocks and five animals per block. Animals in both silvopastoral and full sun treatments grazed B. decumbens , and animals in both treatments presented with clinical symptoms, alterations in the liver, and increased serum levels of gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), and bilirubin over the duration of the experiment. Although the protodioscin content of B. decumbens in the silvopastoral system was lower than in the full sun treatment, it was sufficient to cause secondary photosensitization in the animals. The natural shading provided by the silvopastoral system does not prevent or ameliorate photosensitization symptoms in young naïve sheep grazing on B. decumbens. [ABSTRACT FROM AUTHOR]

This study assessed the effects of irrigation with different dilutions of sludge water, a wastewater from an aluminium-based drinking water treatment plant in Harare, Zimbabwe, on yield and elemental uptake of Brachiaria decumbens (brachiaria) and Medicago sativa (lucerne), and on properties of clay and sandy loam soils. The sludge water was characterised and diluted to 25%, 50% and 75% of the original concentration with tap water. The dilutions, together with 100% sludge water and tap water, were used to irrigate brachiaria and lucerne in a pot experiment. Shoot plant material was harvested and analysed for biomass, total nitrogen (N), phosphorus (P), Ca, Mg, K, aluminium (Al), boron (B), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn). Soils were analysed for particle size distribution, organic carbon, (before use only), pH, exchangeable acidity and extractable P, Fe, Mn, Cu and Zn before use and after harvesting. Increasing sludge water concentration increased yield and uptake of nutrients of both crops, without accumulating pollutants in the tissues to phytotoxic levels in both soils for brachiaria and in the sandy loam soil for lucerne. Tissue Al and Fe were not affected by sludge water concentration but were higher than maximum tolerable levels. An increase in sludge water concentration increased soil pH in the sandy loam soil more than in the clay under both crops. Undiluted sludge water may be used to irrigate brachiaria, while dilution to 75% of its original concentration is required for lucerne, at least in the short term, without negatively affecting plant growth. [ABSTRACT FROM AUTHOR]

The chemical weed control in sugarcane during the wet season is more effective than the control carried out during the dry season. The objective of this study was to evaluate the efficacy of herbicides in the rainy season and in the dry season in sugarcane crop, and in different soil textural classes. The experiments simulated dry season and rainy season basing on periods of days in which experiment was submitted to irrigation restriction. In each experiment, it was tested 50 and 100% of the dose of the main herbicides commonly used in sugarcane to control B. decumbens, B. plantaginea, P. maximum and D. horizontalis. In general, in dry conditions, as well as varying the soil texture, there are restrictions in the choice of herbicide to be used due to the reduced effectiveness of some treatments in certain situations. In the very-clayey soil, especially in the dry season, the efficacy of herbicides is better, whereas, for the sandy-clay-loam soil in dry conditions, the effectiveness of herbicides is restricted. Thus, this study, despite the great complexity of the variables to be analyzed, permitted to establish guidelines for decision making on the most appropriate herbicide to be applied in each studied condition, in order to control these weed species. [ABSTRACT FROM AUTHOR]

Objective: Effects of nitrogen supplementation associated with different levels of starch on voluntary intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage (Brachiaria decumbens hay, 7.4% crude protein, CP) were evaluated using ruminal and abomasal cannulated steers. Methods: Five European×Zebu young bulls (186 kg body weight, BW) were distributed according to a 5×5 Latin square. The following treatments were evaluated: control, supplementation with 300 g CP/d (0:1), supplementation with 300 g starch/d and 300 g CP/d (1:1), supplementation with 600 g starch/d and 300 g CP/d (2:1), and supplementation with 900 g starch/d and 300 g CP/d (3:1). A mixture of nitrogenous compounds provided 1/3 from true protein (casein) and 2/3 from non-protein nitrogen (mixture of urea and ammonium sulphate, 9:1) was used as the nitrogen supplement. In order to supply energy a unique source of corn starch was used. Results: Supplements increased (p<0.05) dry matter intake, but did not affect (p>0.05) forage intake. There was a cubic effect (p<0.05) of starch on voluntary intake. This was attributed to the highest forage intake (g/kg BW) when using the 2:1 starch:CP ratio. Supplements increased (p<0.05) organic matter (OM) digestibility, but did not affect (p>0.05) neutral detergent fibre corrected for ash and protein (NDFap) digestibility. There was a positive linear effect (p<0.05) of the amount of starch supplemented on OM digestibility. Total NDFap digestibility was not affected (p>0.05) by the amount of supplemental starch. Ruminal ammonia nitrogen concentrations were higher (p<0.05) in supplemented animals, however, a negative linear effect (p<0.05) of amount of starch was observed. Supplements increased (p<0.05) the nitrogen balance (NB) and efficiency of nitrogen utilization. These effects were attributed to increased body anabolism, supported by higher (p<0.05) serum concentration of insulin-like growth factor 1. Increasing the amount of starch tended (p<0.06) to linearly increase the NB. In spite of this, there was a highest NB value for the 2:1 starch:CP ratio amongst the treatments with supplementation. Conclusion: Nitrogen supplementation in cattle fed low-quality tropical forage increases nitrogen retention in the animal's body. An additional supply of starch increases nitrogen retention by increasing energy availability for both rumen and animal metabolism. [ABSTRACT FROM AUTHOR]

Plants compete for several resources on soil, including water, light and nutrients which can affect crop yield and also weeds growth. Under the hypothesis that in different densities and weed communities, crops and weeds undergo changes in their nutritional contents of macro and micronutrients, the aim of this study was to quantify the nutritional contents of bean plants and weeds cultivated in increasing densities (0, 74, 147, 221 and 295 plants m-2) and the effect of the association of plants (isolated bean, bean + Urochloa plantaginea, bean + Bidens pilosa and bean + Urochloa plantaginea + Bidens pilosa). The contents of macro and micronutrients were evaluated. The increase in plant density promoted a decrease in the total chlorophyll content of bean plants and weeds, as well as a decrease in macronutrients (K and P) and micronutrients (Zn, Fe, Mn and Cu). In the arrangement where the greatest number of species were cultivated simultaneously and in increasing densities, a greater reduction in total chlorophyll content and in macro and micronutrient contents of the three species (crops and weeds) were observed. [ABSTRACT FROM AUTHOR]

The silvopastoral system has been suggested as an alternative to recover degraded pastures in tropical regions. However, trees reduce the light available for pastures, which may affect the growth and herbage accumulation. The objective of this study was to evaluate the morphogenesis, canopy structure and herbage accumulation of signalgrass (Brachiaria decumbens) subjected to three light regimes (0, 20 and 70% of natural shading) and two fertilization levels (presence or absence of nitrogen, phosphorus and potassium). Leaf and stem elongation rates increased under shading but did not vary with fertilization. The leaf appearance rate was greater under fertilizer treatment but was generally similar among light regimes. The tiller density was greater in full sun and lower in intense shading. Tiller density responded to fertilization under full sun and moderate shading. Herbage accumulation increased by 42% with fertilization under full sun, 12% under moderate shading and did not vary under intense shading. Results showed that even under fertilization the herbage accumulation was limited by reduced light. However, under moderate shade the fertilization was important to raise tiller population over the growth cycles. [ABSTRACT FROM AUTHOR]

In recent decades, the micro-region of Paraiba state, Brazil, has been undergoing the process of replacing its native coverage by crops, mainly pastures for grazing. This land use change has led to the detachment of soil due to the water erosion. Thus, this research had the merit of analyzing the hydraulic roughness parameters generated by pasture emergent vegetation in field condition under interrill erosion. This study was conducted in a randomized block with 4 treatments and 5 replicates, totaling 20 experimental plots. The treatments comprised different slopes (15%, 25%, 35% and 45%) in an Ultisol. The mean flow velocity and the rate of infiltration in the pasture varied significantly with the increase in slope, contributing to increasing erosion rates until 35% slope. For the slope equal to 45%, the largest soil loss was not observed, chiefly because the crop covers offset the effects generated by the increase in the slope and also due to the remotion of surface horizon (A horizon) which was removed by previous water erosion, which now acted directly on the B horizon. The vegetation drag coefficient ( C D ′) of the pasture exhibited an increase when occurred a reduction of turbulent flow between plants. In the condition of increasing in flow depth (h) there was a greater energy flux between the mass of water and the plant structure of Brachiaria decumbens that resulted in the decrease of the vegetation resistance force (Fdrag). [ABSTRACT FROM AUTHOR]

Signal grass (Brachiaria decumbens cv. Basilisk, syn. Urochloa decumbens Stapf R.D. Webster) has been widely grown in the Brazilian tropics over the last 40 years, but management recommendations have been largely empirical and not based on canopy targets. This study was designed to characterise and explain the impact of canopy-based grazing strategies on herbage accumulation, plant-part composition, and nutritive value of signal grass. Treatments were factorial combinations of two stubble heights, 5 cm (SH5) and 10 cm (SH10), and two grazing frequencies, grazing initiated when 95% (LI95) and 100% (LI100) of incoming light was intercepted by the canopy. Rest periods were imposed during summer and autumn of both experimental years. Leaf blade accumulation was greater for LI100 than LI95 (9.5 v. 8.8 t/ha) associated with increased stem accumulation (4.6 v. 3.5 t/ha for LI100 v. LI95). The SH10 pastures produced more stem than SH5 pastures (4.4 v. 3.6 t/ha), with no difference in leaf blade accumulation. In general, SH10 pastures had more residual leaf blade mass post-graze, whereas SH5 pastures combined with higher grazing frequency (SH5-LI95) became more prostrate over time, increasing leaf blade proportion in post-graze forage. Over time, stubble height had more influence than grazing frequency on leaf blade proportion at pre-graze, and SH5 pastures had leafier canopies than SH10 pastures. Digestibility was less under LI100, especially when associated with SH5 stubble (SH5-LI100), regardless of season of the year. To provide optimal leaf blade yield and overall forage digestibility, particularly during warm, rainy seasons, defoliation of signal grass should include pre-graze height varying from 18 to 30 cm (95-100% of light interception) and mean stubble height close to 10 cm. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare structural, morphological and bromatological characteristics of forage as well as performance of Caracu beef cattle (200 ± 9 kg of initial body weight) supplemented with a multi-mineral mixture (0.25% of body weight) on deferred pastures of Brachiaria brizantha 'Marandu' and Brachiaria decumbens 'Basilisk' under continuous grazing. After the pasture was grazed to 10 cm of height, in March 2014, both grasses were left to rest and subjected to a 126-day deferment period. The experimental period lasted from July to October 2014; the sward characteristics and the animal's weight were evaluated every 28 days. The highest forage mass was recorded in 'Marandu' grass, whereas the highest leaves percentage and lowest dead material percentage were observed in 'Basilisk' pastures. Similarly, the highest crude protein content (8.1 vs. 7.0 ± 0.2%), in vitro organic matter digestibility (57.7 vs. 53.9 ± 0.4%), lowest neutral detergent fiber content (69.2 vs. 72.7 ± 0.4%), and; consequently, the highest average daily gain (680 vs. 530 ± 0.04g animal-1) were recorded for 'Basilisk' pastures. 'Marandu' and 'Basilisk' deferment was associated with a multi-mineral mixture supplementation as a management alternative for rearing beef cattle during the drought periods. Because of the duration of the pasture recovery period in this study, B. decumbens pastures were more likely to achieve the highest animal performance. [ABSTRACT FROM AUTHOR]

In the face of various areas of native forests converted in recent years in areas for the cultivation of agricultural species, seeking increased production, this work aimed to evaluate the physical properties of soil in areas cultivated with grassland and eucalyptus converted from forest Atlantic area. The experiment was subdivided plots with three replications, as the plots three different areas, native forest (original cover), pastures and eucalyptus, and the subplots three depths (0.00-0.20; 0.20-0.40 and 0.40-0.60 m). Undisturbed samples were used for the determination of soil density, macro and microporosity, geometric mean diameter (GMD) and ponderate (PMD). The grassland and eucalyptus showed higher soil density compared to native forest. The native forest and eucalyptus showed higher microporosity in the deeper layers, differing from the surface layer of the soil showed lower microporosity and macroporosity greater. Eucalyptus coverage showed higher GMD and PMD between the converted areas, already the largest GMD and PMD were found in native forest cover, differing from the others. The conversion of Atlantic forest area of farmland affected the physical properties of soil only in the depth of 0.00 to 0.20 m above the ground. The physical properties of eucalyptus area were the most neared the native forest. [ABSTRACT FROM AUTHOR]

The objective of this work was evaluate the association between morphogenetic and structural characteristics of Brachiaria decumbens managed at different doses of nitrogen. The experimental design was a randomized block with four replications. Four levels of nitrogen fertilization were evaluated: 100; 200; 300 and 400 kg of N ha-1 as urea, divided in two doses during the rainy season (January to March) and the control treatment without fertilization. There was an increase in leaf appearance rate (LAR), leaf elongation rate (LER) and tiller number (NP) up to 21.4%; 23.8% and 50.5% for the highest dose of N (400 kg N ha-1) compared to the control group, respectively. There was a positive correlation (r = 0.53) (p<0.05) between the LER and leaf life span (LLS). The phyllochron showed high negative correlation (r = -0.81) (p<0.0001) with LAR. Regarding the final length of the stem, there was no correlation effect (p>0.05) with other analyzed characteristics. [ABSTRACT FROM AUTHOR]

The breeding program Brachiaria developed by Embrapa Beef Cattle provides studies to obtain forage with agronomic characters desired by farmers. In this regard, in 2013 and 2014, a study was carried out in order to select the best Brachiaria decumbens intraspecific hybrids, which are superior in relation to production, forage nutritional value, and resistance to spittlebugs. Estimates of genetic parameters and gains with selection were carried out. It was found that there was significant variability between genotypes for all characters. Gain with selection (GS%) ranged from 12 to 324%, and the highest percentage was found for weight of pure seeds (PS) of seed collectors of the second harvest. For reproductive tillers (RT), C001 and R091 hybrids had better performance than the control, and this character may be considered as a parameter to estimate production of pure seeds before flowering starts. [ABSTRACT FROM AUTHOR]

Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic heritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR-BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR-BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR-BBML as candidate genes for the apomictic function of parthenogenesis. [ABSTRACT FROM AUTHOR]

Deposition and decomposition of arboreal vegetation represent crucial but poorly understood soil nutrient and organic matter cycling components of warm climate silvopastoral systems. Biomass loss and nutrient release from decomposition bags with leaves (Exp. 1) or branches (Exp. 2) of the arboreal legumes gliricidia [Gliricidia sepium (Jacq.) Kunth] and sabiá (Mimosa caesalpiniifolia Benth.) in a signal grass [Brachiaria decumbens (Stapf) R.D. Webster] silvopastoral system were measured in 2011 and 2012. In Exp. 2, branches were divided into 0- to 3-, >3- to 9-, and >9- to 20-cm circumference classes. The incubated nylon bags were collected 0, 4, 8, 16, 32, 64, 128, and 256 d after placement on the soil surface. Gliricidia leaves and branches, in general, had higher N and lower acid detergent lignin (ADL) concentrations and ADL/N ratios than those of sabiá. Gliricidia leaf biomass loss rates were greater (P < 0.001; k = 0.0038 g g-1 d-1) than those of sabiá (k = 0.0012 g g-1 d-1), as were the branch biomass loss rates (gliricidia, k = 0.0018 g g-1 d-1; sabiá, k = 0.0005 g g-1 d-1). Leaf N release from the fixed amounts incorporated as annual litterfall corresponded to 47 and 14 kg N ha-1 from gliricidia and sabiá, respectively. The differences in concentrations and decomposition rates of the various fractions indicate that the two legume species differ in their nutrient recycling capacities. [ABSTRACT FROM AUTHOR]

Objective. The objective was to study the clinical and histopathological aspects of Phototoxic Dermatitis Secondary (PDS), secondary to ingestion of Brachiaria decumbens in Zebu calves (Bos indicus) department of Cordoba, Colombia. Materials and methods. Twelve calves Zebu, male, 12 to 18 months, PDS diagnosed with clinical, histopathologically studied and laboratory exams. Results. Clinically, signs of photophobia, dehydration, progressive emaciation, icteric mucous membranes and skin lesions as res-breaking with leathery skin appearance, skin peeling and scabbing over large areas were evident. The lesions were located bilaterally in different areas of the skin in ears, perineal region, epigastric and costal. Serological tests gave the high catalytic activity of the liver enzymes AST and GGT indicating liver injury consistent with cholestasis. Histopathologically was observed in hematoxylin eosin, chronic necrotic dermatitis, in trichrome Gomori poor dermal proliferation disorganized fibroblasts, low presence of diffuse connective tissue and collagen fibers disorganized and picrosirius red / polarization areas reddish birefringence was observed was observed and greenyellow, indicating moderate presence of mature collagen type I (bright red in polarization) and Type III (bright yellowish-green polarization). Conclusions. The definitive diagnosis of the disease was based on clinical features, laboratory findings and histopathological findings, being conclusive as diagnostic methods of the PDS. In the literature there are no reports of studies PDS in Zebu calves department of Córdoba and Colombia. [ABSTRACT FROM AUTHOR]

Brachiaria decumbens has great importance in the national beef cattle scenario due to its high forage yield potential and high adaptability to acid soils and low fertility. In order to obtain new cultivars, intraspecific hybrids, previously selected by the Brachiaria breeding program, were evaluated in 2013 and 2014 for phenological characteristics and seed production potential through their production components, aiming to obtain cultivars with satisfactory production agronomic characteristics and forage yield, resistant to 'cigarrinhas-das-pastagens' (Tomaspia sp.) and good seed production. Estimates of phenotypic correlation and analysis of variance were performed using the SAS 9.3 software. From the results obtained in both consecutive years, it was observed that there was a correlation between the reproductive tiller number (RT) and the pure seeds (PS) weight in the seedbeds of the second year of production around 70% (p < 0.01), which can be considered as a parameter to estimate the production of pure seeds before the start of flowering. [ABSTRACT FROM AUTHOR]

The objective of this work was to estimate genetic parameters for agronomic traits and resistance to spittlebugs in B. decumbens hybrids and to select the ones with best performance. For that, 324 hybrids were evaluated in field plots for agronomic traits and in the greenhouse for resistance to spittlebugs. Genetic variability amongst the hybrids was observed for all traits analyzed. The heritability estimates between genotypes means were higher than 0.52 for all agronomic traits and 0.98 and 0.99 for nymphal survival and nymphal period duration respectively. Hybrids with better performance than cultivar Basilisk for each individual trait were identified and also through a selection index combining all traits. Assigning weights to the different traits in the selection index did not significantly alter the rank for superior hybrids. Those were selected to continue on to the next phases of the breeding program. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate hybrids of Brachiaria decumbens for root vigor and aluminum resistance as components of edaphic adaptation. One hundred intraspecific hybrids and their parents were evaluated in a greenhouse solutionculture. Significant differences for both traits indicate that there is genetic variability amongst hybrids. The parents had a similar performance for root growth, but differed significantly for aluminum resistance. Twenty three and seven hybrids were superior to cv. Basilisk for root vigor and aluminum resistance, respectively, but most of them were not coincident for both traits. Aluminum resistance seemed to vary quantitatively, since the majority of the hybrids were placed around the mean and fewer in the extremes. The estimate of heritability based on progeny means for aluminum resistance (0.27) was lower than for root vigor (0.69). The method used was efficient in discriminating hybrids, and identified the best ones for edaphic adaptation. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizae microscopy requires differential staining of typical structures. Dyes employed, such as trypan blue, pose risks to health and environment. Alternative dyes such as pen ink and aniline have variable coloring efficiency. In this work, Brachiaria decumbens roots, discolored with caustic soda (NaOH), were stained with açai, annatto, saffron, trypan blue and pen inks. There were significant differences among dyes regarding stained mycorrhizal structures and pictures quality. Acai was considered the best alternative dye, with similar results to trypan blue. [ABSTRACT FROM AUTHOR]

This is the first study to investigate the activity of thymol on Rhipicephalus microplus larvae under semi-natural conditions. For this purpose, tests were conducted in pots with Brachiaria decumbens seedlings containing cattle tick larvae. Thymol, diluted in ethanol 50° GL, was tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 mg/mL, along with the control group treated with the solvent alone. Each treatment was composed of five pots (1 pot = a repetition). The experiment was performed in three steps. On the first day, the larvae were applied at the base of the signalgrass. Twenty-four hours later, approximately 25 mL of the solution was applied with thymol on the top of the vegetation in each pot. The survival of the larvae was measured 24 h after application of the solutions. Each pot was analyzed individually, and the grass fillets contained larvae were cut with scissors, placed in Petri dishes, and taken to the laboratory to count the number of living larvae. At the highest concentrations (10, 15, and 20 mg /mL), the number of live larvae declined by more than 95 % in relation to the control group. The lethal concentration 50 % (LC50) and LC90 values were 3.45 and 9.25 mg/ml, respectively. The application of thymol in semi-natural conditions starting concentration of 10 mg/mL significantly reduced the number of living R. microplus larvae. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate whether environmental changes promoted by the conversion from a Brachiaria decumbens monoculture to a silvopastoral system can be measured by the diversity, richness, abundance, and constancy of insects of the order Hymenoptera. A Malaise trap for collecting insects was installed in a B. decumbens area managed as a silvopastoral system, and another was installed in a monoculture system. Hymenoptera richness and abundance were determined based on the number of morphospecies and specimens, respectively. The diversity and constancy indices were calculated using the Shannon-Wiener and Bodenheimer methodologies. Fifteen families of Hymenoptera were collected, seven of which were unique to the monoculture system. The samples from the silvopastoral system were significantly more abundant (3,889) and rich (305) compared with those from the monoculture system, which were much less abundant (1,473) and rich (173). Similar trends were noted for the families Formicidae, Ichneumonidae, and Braconidae. Additionally, these families and Sphecidae showed significantly greater diversity in the silvopastoral system. Formicidae and Braconidae were constant in both systems, while Ichneumonidae was constant only in the silvopastoral system. The families Vespidae, Pompilidae, and Apidae were more diverse; Chaleididae, Pompilidae, Sphecidae, Halictidae, Evaniidae, and Gasteruptiidae were more abundant; and Vespidae had more richness in the monoculture system. The conversion from the monoculture system to the silvopastoral system can be measured by the occurrence of Hymenoptera, especially the families Formicidae, Ichneumonidae, and Braconidae, which can be used as potential bioindicators. [ABSTRACT FROM AUTHOR]

ABSTRACTUsing a compartmentalized treatment technique, the role of arbuscular mycorrhizal fungi (AMF;Acaulospora scrobiculata) on arsenic (As) uptake and translocation inBrachiaria decumbens. Treatments consisted of a factorial arrangement of three As doses (0, 50, and 100 mg kg−1) and the presence/absence of AMF inoculates. In the absence of AMF,B. decumbensdid not show As accumulation, indicating the probable presence of tolerance mechanism via As exclusion by the roots.B. decumbensplants showed high AMF colonization levels, especially in the arsenic treatments, with AMF improving shoot and root growth independent of As concentrations. Arsenic accumulation occurred only with AMF inoculation. Phosphorous uptake was reduced inB. decumbensroots in the presence of arsenic with and without inoculation of AMF. Results suggest thatB. decumbenscan be used in phytoremediation procedures when inoculated withA. scrobiculata, although pasture formation should be strictly avoided in contaminated sites. [ABSTRACT FROM PUBLISHER]

An experiment was conducted on a Red Ferralitic Lixiviated soil in order to assess the contribution of arbuscular mycorrhizal inoculation to reduce phosphorus fertilization in Brachiaria decumbens cv. Basilisk. Doses of 0, 30, 60 and 90 kg P2O5 ha-1 year-1, alone and combined with the inoculation of arbuscular mycorrhizal fungal strain Glomus cubense, previously selected for its high efficiency, were distributed in a randomized block design with 4x2 factorial arrangement and four replications. The experiment was conducted under irrigated conditions and lasted two years. G. cubense significantly increased mycorrhizal colonization percentages, visual density and spore number in the rhizosphere, although the values of those variables decreased with the highest doses of P2O5. In non inoculated treatments, the highest yields and P extractions in the aerial biomass were obtained with doses of 30-90 kg of P2O5 ha-1, with no significant differences between them, but only with the inoculation of G. cubense, during the first year of the establishment of grass both indicators reached values similar to those obtained with phosphoric fertilizer applications without inoculation. The influence of G. cubense was observed until the rainy season of the second year, although fungal variable values, yields and P exports with the aerial biomass indicated a decrease in the effectiveness of inoculation, in relation to the first year. [ABSTRACT FROM AUTHOR]

The phytoextraction of heavy metals using chelating agents has been widely studied for the remediation of contaminated soils. To evaluate the efficiency of EDTA-induced phytoextraction of Ba and Pb using Brachiaria decumbens for the remediation of soil contaminated by oil well drilling and exploration waste, an experiment was conducted by applying a single dose (6 mmol EDTA kg-1 soil) and split doses of EDTA (three applications of 2 mmol EDTA kg-1 soil). The samples were subjected to sequential extractions using the method proposed by Ure et al. (1993) as modified by Rauret et al. (1999).The application of EDTA did not influence the distribution of Ba in various chemical fractions of the soil. The dry matter production did not differ significantly between the treatments and the control, thereby demonstrating the tolerance of plants to the experimental conditions. The absorption of Pb by plants was influenced by the application of EDTA. The application of a single dose of EDTA influenced the absorption of Pb and its translocation to the aerial plant parts. The application of split doses favoured higher accumulation of Pb in roots. Because of its tolerance to heavy metals and EDTA, B. decumbens has the potential to be used in phytostabilisation. [ABSTRACT FROM AUTHOR]

In the Orinoco lowlands, savannas have been often replaced by pastures composed of the C grass, Brachiaria decumbens Stapf. We addressed following questions: ( 1) How does the replacement of the native vegetation affect CO exchange on seasonal and annual scales? ( 2) How do biophysical constraints change when the landscape is transformed? To assess how these changes affect carbon exchange, we determined simultaneously the CO fluxes by eddy covariance, and the soil CO efflux by a chamber-based system in B. decumbens and herbaceous savanna stands. Measurements covered a one-year period from the beginning of the dry season (November 2008) to the end of the wet season (November 2009). During the wet season, the net ecosystem CO exchange reached maximum values of 23 and 10 μmol(CO) m s in the B. decumbens field and in the herbaceous savanna stand, respectively. The soil CO efflux for both stands followed a temperature variation during the dry and wet seasons, when the soil water content (SWC) increased above 0.087 m m in the latter case. Bursts of CO emissions were evident when the dry soil experienced rehydration. The carbon source/sink dynamics over the two canopies differed markedly. Annual measurements of the net ecosystem production indicated that the B. decumbens field constituted a strong carbon sink of 216 g(C) m y. By contrast, the herbaceous savanna stand was found to be only a weak sink [36 g(C) m y]. About 53% of the gross primary production was lost as the ecosystem respiration. Carbon uptake was limited by SWC in the herbaceous savanna stand as evident from the pattern of water-use efficiency (WUE). At the B. decumbens stand, WUE was relatively insensitive to SWC. Although these results were specific to the studied site, the effect of land use changes and the physiological response of the studied stands might be applicable to other savannas. [ABSTRACT FROM AUTHOR]

This research was carried out to study the interaction between the corn and Urochloa spp. cultivars in association, as well as the interference of weeds in this cropping system. A randomized experiment in three blocks with split-plots design was conducted. The plots consisted of seven cropping systems (Urochloa brizantha cv. 'Marandu' and cv. 'Piatã' and U. decumbens cv. 'Basilisk' a sole culture and in association with corn as well as the sole culture of corn) and the split-plots by weed control (with and without weeding). It was found that the establishment of corn-Urochloa spp. cultivars association does not affect yield components such as height and grain yield, nor reduces the weed community, but interferes in the density, mass of dry matter per plant and per area of Urochloa spp. cultivars. There were similar levels of interference of weeds between cropping systems without weeding due to the similarity between the weed communities, showing the predominance of species considered as highly competitive such as Panicum maximum and also due to the low infestation with predominance of species such as Richardia brasiliensis and Ageratum conyzoides, associated with weed control. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to report the study of hepatogenous photosensitization in buffaloes during two outbreaks provoked by ingestion of Brachiaria decumbens in Minas Gerais state, Brazil. Ten young buffaloes in outbreak 1 and seven buffaloes in outbreak 2 were intoxicated by B. decumbens. Nine clinically healthy buffaloes raised under the same conditions as the sick animals served as the control group. All animals were subjected to clinical examination, and serum was collected to measure gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), direct bilirubin (DB), indirect bilirubin (IB) and total bilirubin (TB) as indicators of liver function and urea and creatinine as indicators of renal function. Histopathology of liver fragments from five different animals was carried out. During the outbreaks and every two months for one year, samples of grass from paddocks where the animals got sick were collected for quantitative evaluation of the saponin protodioscin, combined with observations of pasture characteristics and daily rainfall. Clinical signs included apathy, weight loss, restlessness, scar retraction of the ears and intense itching at the skin lesions, mainly on the rump, the tail head, neck and hindlimbs, similar to the signs observed in other ruminants. Only the GGT enzyme presented significantly different (P < 0.01) serum levels between intoxicated animals (n = 17) and healthy animals (n = 9), indicating liver damage in buffaloes bred in B. decumbens pastures. Microscopy of the liver showed foamy macrophages and lesions of liver disease associated with the presence of crystals in the bile ducts, which have also been found in sheep and cattle poisoned by grasses of the genus Brachiaria. During the outbreaks, protodioscin levels were higher than 3%, and shortly after, these levels were reduced to less than 0.80%, suggesting a hepatic injury etiology. The outbreaks took place at the beginning of the rainy season, and there was a positive correlation between saponin and the amount of rainfall, as well as between saponin and the amount of green leaves in the pasture. These findings indicate that the grass was more toxic in this period. This is the first report of photosensitization by B. decumbens in buffalo. [Copyright &y& Elsevier]

Irradiance and soil nitrogen effects on growth, net photosynthesis and radiation use efficiency (RUE) of Brachiaria decumbens were investigated in fertilized and non-fertilized stands. Three levels of photosynthetic photon flux ( PPF: S0 = 100%, S1 = 50% and S2 = 30%) and two N supplies, with ( N+) and without ( N−), were used. Forage biomass and nutrient accumulation, specific leaf area ( SLA), leaf area index ( LAI), fractional intercepted photosynthetic photon flux (f PPF), leaf photosynthetic response to light and efficiency of radiation use at leaf ( A/ Q) and canopy ( RUE) levels were measured. Shade effects were mostly independent of soil N. Final yield was decreased by 34% ( S1) and 57% ( S2). Shade increased SLA (25-46%), so maximum LAI (2·4-3·3) was similar among light regimes. In N− stands, reductions in leaf biomass (14%), SLA (17%) and LAI (27%) were recorded, although forage yield was similar between soil N conditions. Under shade, peaks of A were comparable to those at full light, so A/ Q was higher around midday. Derived parameters of the A- PPF curves were similar between S0 and S2. A maximum f PPF = 0·8 ( S0 N+, S1 N+) was recorded at LAI = 3-4. Under limited sunlight, relatively high RUE (1·6-2·8 g MJ−1) were observed over both soil N conditions. We concluded that B. decumbens had a high plasticity to shade, thus explaining its success under silvopastoral systems. [ABSTRACT FROM AUTHOR]

This study evaluated the impact of different CO levels on the biological characteristics of Mahanarva spectabilis (Distant) and on the performance of forage grasses. The signal grasses Brachiaria decumbens Stapf (susceptible) and Brachiaria brizantha (A. Rich.) (resistant), the elephant grass Pennisetum purpureum (Schum.), including the Roxo de Botucatu cultivar (susceptible) and the Pioneiro cultivar (resistant) and the insects were kept in climate-controlled chambers with constant low (250 ppm) CO levels, constant high (500 ppm) CO levels, or fluctuating CO levels (mean, 368 ppm). Among these three CO treatments, no significant differences were found in the nymphal survival of M. spectabilis when the nymphs were fed on two signal grass species. On the other hand, under a constant low CO level (250 ppm), nymphal survival rates were significantly lower when the insects were kept in Roxo de Botucatu and Pioneiro cultivars. The mean adult longevity values for M. spectabilis were not significantly different among the three levels of CO evaluated. We observed that increased CO levels improved the performance of M. spectabilis and elephant grass cultivars in accumulating dry mass, which was not evident in signal grass. We further conclude that the levels of susceptibility and resistance of the forages tested will be maintained in future scenarios under which atmospheric CO levels are expected to increase. [ABSTRACT FROM AUTHOR]