Gustavo José Braga

Testing animal performance under grazing is fundamental to determine the potential of recently released, high‐yielding Urochloa decumbens hybrids. The objective was to evaluate the weight gain of young bulls grazing on pastures of U. decumbens cultivars Basilisk, BRS Carinás, and BRS Poraitê, as well as to assess the nutritive value and plant‐part composition of the forage. The experiment was conducted over 2 years in a clay soil, using a randomized block design with three replicates. Pastures were managed under continuous stocking with a variable stocking rate (SR), aiming to maintain a canopy height of 25 cm. In contrast to the leaf blade and stem, the amount of dead material increased from the rainy to the early dry season, with Basilisk showing a greater mean value (1314 kg DM/ha), followed by Poraitê (1150 kg DM/ha) and Carinás (1127 kg DM/ha) ( p < 0.10). Carinás and Poraitê had slightly greater crude protein (CP) (114 g/kg) compared to Basilisk (105 g/kg), particularly during the first year. Animals grazing Carinás had greater average daily gain (ADG) (0.62 kg LW) compared to Poraitê (0.54 kg LW), and similar performance to Basilisk (0.59 kg LW). In terms of live weight gain per area (GA), Carinás outperformed the other cultivars, reaching 406 kg LW/ha/year, compared to 359 and 358 kg LW/ha/year for Basilisk and Poraitê, respectively, due to the greater ADG and the increased SR observed during the rainy season. Carinás and Poraitê have potential for promoting cattle growth, owing to their comparable forage quality and plant‐part composition to Basilisk. However, the superior live weight gain per area observed for Carinás demonstrates its greater carrying capacity, without compromising individual animal performance.

This study aimed to evaluate the morphological diversity of 22 Crotalaria accessions conserved in the Embrapa Cerrados germplasm bank, Brazil, with emphasis on their potential use in breeding and genetic resource management. Sixteen morphological descriptors were analyzed, revealing substantial phenotypic variation among accessions. Plant height ranged from 45 to 146cm, and leaflet and seed traits also showed broad variation, reflecting a wide adaptive spectrum. The Shannon–Weaver (H) and Simpson (D) diversity indices indicated consistently high diversity across traits (mean H = 0.964; mean D = 0.940), confirming the existence of a rich genetic base within the collection. Principal component analysis showed that the first two components explained 63.72% of total variance, with reproductive traits such as seed length, seed width, and 100-seed weight contributing most to variation among accessions. Cluster analysis grouped the accessions into five distinct morphological clusters, identifying genotypes with superior plant vigour, leaf area, or seed characteristics as potential parents for future breeding programmes. The observed morphological variability highlights the significant genetic diversity within Crotalaria germplasm, supporting its value for selection, hybridization and conservation. The combination of diversity indices and multivariate analyses provides a robust framework for identifying promising accessions for breeding programmes targeting biomass production, seed yield and environmental adaptation. These findings reinforce the importance of maintaining and characterizing germplasm collections as strategic reservoirs for sustainable crop improvement and the long-term conservation of genetic resources.

Gamba grass (Andropogon gayanus Kunth) is a promising forage alternative for Brazil’s Cerrado regions, attracting increasing research interest due to its potential to complement or replace widely planted species such as Urochloa and Megathyrsus. Despite the release of three cultivars, significant improvements in dry matter (DM) yield and forage quality are needed to fully realize its agronomic potential. This study aimed to evaluate genetic variability, estimate narrow sense heritability, and predict expected genetic gains for DM yield and key forage quality traits in two gamba grass populations derived from the cultivars BRS Sarandi and Planaltina. Trials were established in spring 2017 in Planaltina, DF, and evaluated during February–March 2018 and January–March 2019. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL), and hemicellulose (HEMIC) were quantified alongside DM yield. BRS Sarandi exhibited higher CP (12.3% vs. 9.8%) and lower NDF (57.1% vs. 63.4%), ADF (36.2% vs. 41.5%), CEL (20.8% vs. 23.7%), and HEMIC (20.9% vs. 21.9%) compared to Planaltina, while DM yield did not differ significantly between populations (4.57 t·ha⁻¹ vs. 4.50 t·ha⁻¹ per harvest, p > 0.05). Heritability estimates for individual harvests ranged from 0.31 to 0.68 for DM yield and 0.28 to 0.62 for quality traits, whereas multi-harvest models across years yielded lower estimates (0.07–0.27). Expected annual genetic gains were modest, with the highest predicted increase for CP (0.45% per year) and the largest decrease for NDF (−0.78% per year), reflecting the quantitative nature of trait inheritance and strong environmental influence. This study provides novel insights by simultaneously comparing two populations for multiple harvests and quantifying both yield and detailed forage quality traits, offering practical guidance for gamba grass breeding strategies. Results indicate that breeding programs should prioritize multiple selection cycles, precise phenotyping, genotypic and potentially genomic selection to accelerate improvement in both DM yield and forage quality, overcoming the constraints of low heritability and multi-trait selection.

Gamba grass, a leading alternative for forage development in Brazil Cerrado’s areas, has received a more extensive researchers' attention in the recent years. Although three cultivars were already released, for gamba grass to be an alternative to most planted forage species in Brazil (Genera Urochloa and Megathyrsus), significant technological improvements need to be achieved, mainly in genetic development of DM yield and forage quality. Understanding genetic variability of populations and the nature of the gene action governing the inheritance of traits are important contexts to obtain genetic gains from selection in breeding programs. The objective was to estimate DM yield and quality traits narrow-sense heritability and expected gains from HS family tests of two populations originated from the cultivars BRS Sarandi and cv. Planaltina. The trials were established in spring 2017 in Planaltina, DF and evaluated in February and March, 2018 and January, February, and March, 2019. Cultivar BRS Sarandi presented better forage quality than did cv. Planaltina due to higher CP and lower NDF, ADF, CEL, and HEMIC contents, and they did not differ for DM yield. Heritability estimates were low to moderate in magnitude for both populations, ranging from 0.31 to 0.68 for individual harvests and from 0.07 to 0.27 for models across harvests and years. Similar low h2 magnitudes across harvests and years were also observed for all quality traits estimated for both populations. The theoretical expected gains per year for all traits reflected modest gains, but all aligned with those from literature. The nature of the genetic variation is quantitative for all studied traits, since they were highly influenced by the environment. Results suggest more elaborated breeding methods, more cycles of selection, and more accurate measurement techniques to improve chances of success when breeding gamba grass for yield and quality. Alternatively, the use of genomic selection may promote a faster improvement of DM yield and forage quality traits, to overcome the constraints of low heritability, number of selection cycles, high costs, and multi-trait selection.

Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its release, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba-grass-based farms by presenting a greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars—Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, for 3 years, namely 2018, 2018–2019, and 2020. The experimental design was a completely randomized block design with two treatments and three replicates, each one continuously stocked at three stocking rates (SR)—1.3, 2.6, and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (green leaf, stem, and dead material), and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than that of Planaltina (0.490 kg/bull/d) (p < 0.10). In the subsequent year (2018–2019), there was no effect of cultivar (p > 0.10), while in 2020 the ADG was again affected by cultivar (p < 0.10), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3–6 pp less than for Planaltina (p < 0.10). As well as for stems, Sarandi pastures presented a shorter CH in 2028 and 2020 (6–7%) (p < 0.10). The positive high correlation of leaf:stem ratio with ADG (r = 0.70) probably predisposed the superiority of Sarandi over Planaltina. The distinguishing plant-part composition of Sarandi canopy promotes increasing weight gain of beef cattle when compared to cv. Planaltina.

Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its releasing, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba grass-based farms by presenting greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars – Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, during 3 years, namely 2018, 2018-2019 and 2020. The experimental design was completely randomized block with two treatments and three replicates, each one continuously stocked at three stocking rates (SR) - 1.3, 2.6 and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (leaf, stem and dead material) and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than Planaltina (0.490 kg/bull/d) (P=0.0839). In the subsequent year (2018-2019), there was no effect of cultivar (P = 0.4089), while in 2020 the ADG was again affected by cultivar (P=0.0412), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3-6 pp lesser than for Planaltina (P

Stylosanthes scabra Vogel is a tropical legume grown in dry tropical and subtropical environments. The objective of this research was to evaluate the genetic diversity of forage quality traits for 80 accessions of S. scabra. Seven plants from each accession were planted in a single-line plot with no replicates at Embrapa Cerrados, Brazil. All plants were harvested 90 days after planting. Crude protein (CP), in vitro dry matter digestibility (IVDMD), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin (LIG), hemicellulose (HEMIC) and cellulose (CELLU) were estimated. Data were submitted to principal component analysis (PCA) and a cluster analysis was performed to identify groups of similarity. Simpson and Shannon–Weaver diversity indices estimated the genetic diversity. The average values of CP, IVDMD, NDF, ADF, LIG, HEMIC and CELLU were 220g/kg, 560g/kg, 516.8g/kg, 368g/kg, 69.4g/kg, 148.8g/kg and 298.6g/kg, respectively. There was a significant difference among collection sites for IVDMD, ADF and CELLU. The first two principal components accounted for 73% of the total variation. The 80 accessions resulted in four clusters, among which significant differences were observed for CP, IVDMD and ADF. Group IV, with 24 accessions, had the highest CP and IVDMD concentrations and the lowest ADF concentration, being the highest-quality forage group. Diversity indices were 0.78 and 0.81 for Simpson’s and Shannon–Weaver’s, respectively. In conclusion, there is genetic diversity for forage quality traits among S. scabra.

The objective of this work was to evaluate the performance of the thermopotassium and thermophosphate agrominerals, as sources of P and K, in an organic pasture consortium of 'Marandu' Urochloa brizantha + Stylosanthes spp. in the Brazilian Cerrado. The organic management was compared with conventional farming using chemical fertilizers, during three years, in two adjacent experiments, one with and the other without previous growth of green manure (Crotalaria juncea). The management treatments were: conventional, with the application of 200 kg ha-1 potassium chloride, 260 kg ha-1 triple superphosphate, and 217 kg ha-1 urea; organic, with the application of 1.0 Mg ha-1 thermophosphate, 2.0 Mg ha-1 termopotassium, and 7.0 Mg ha-1 chicken manure; and control, without fertilizers. Soil fertility, dry mass production, and legume content in the pasture were evaluated. The experiment with green manure resulted in a significant increase in the soil-extractable contents of P and K and in pasture productivity. In the organic treatment, due to the slow release of agromineral nutrients, long-term effects are observed on the soil-extractable contents of P and K.

In order to optimize the regrowth and harvest of signal grass ( Urochloa decumbens) cv. Basilisk pastures it is necessary to establish more precise grazing management guidelines. The objective of this study was to evaluate herbage accumulation, plant-part composition and nutritive value of signal grass managed under contrasting levels of steady-state canopy heights. Treatments included 3 canopy height targets, i.e. 10 (S-short), 17.5 (M-medium) and 25 cm (T-tall), in a completely randomized design with 4 replications. Experimental units were 144-m(2) plots which were grazed by groups of steers for short periods in an endeavor to keep canopy heights at the 3 desired targets. On average, herbage accumulation rate (HAR) in T pastures was greater than in M and S pastures, including the dry-wet season transition period in spring (September-November). The S pastures had higher crude protein and lower acid detergent fiber concentrations than M and T pastures, especially in the first half of the calendar year. However, in vitro organic matter digestibility was similar for all treatments (612 g/kg). As S and M pastures had lower HARs than T pastures in the spring, it appears advantageous to maintain the signal grass canopy at similar to 25 cm in order to ensure quick regrowth with the return of the wet season. However, longer-term studies are needed with recording of animal performance before these initial findings can be promoted widely.

The use of stylosanthes in mixed grass‐legume pastures may minimize the decline in forage quality and quantity that occurs in monoculture grass pastures, even though the availability of commercial cultivars in Brazil is still limited. The objective of the study was to evaluate the liveweight (LW) gain of young Nellore bulls in a mixed pasture of Brachiaria brizantha (cv. Paiaguás) with the latest release Stylosanthes guianensis cv. Bela. The study was conducted in Planaltina, FD, Brazil, from September to August in two consecutive years, right after seeding. The experimental design was a randomized complete block design with two treatments (mixed or monoculture Paiaguás pastures) and three replicates. The average daily gain (ADG) was on average greater in mixed pastures (0.436 vs. 0.350 kg head⁻¹ day⁻¹ in mixed and grass pastures respectively), particularly in the dry period (0.344 vs. 0.183 kg head⁻¹ day⁻¹). The benefit of mixed over monoculture grass pastures throughout the year was 22 kg LW/head and 55 kg LW/ha. The presence of stylosanthes increased the crude protein (CP) concentration in mixed pastures (120 g/kg) when compared to monoculture grass pastures (109 g/kg), probably influencing the ADG of bulls. The increase of liveweight gain, predominantly in the dry season, makes the high‐protein stylosanthes cv. Bela an alternative to buffer the seasonal deficit of forage quality in newly seeded grass pastures.