Carla Silva Chaves

Sustainable pasture intensification requires efficient nitrogen (N) use while limiting greenhouse gas (GHG) emissions. In this study, the effects of biochar-based nitrogenous organomineral fertilizers (OMF-N) on GHG emissions, nitrogen use efficiency (NUE), and forage accumulation of Ipyporã grass ( Urochloa ruziziensis × Urochloa brizantha ) under deferred grazing management were evaluated. The study was conducted in 2022 and 2023 using a randomized complete block design with four replications. Seven treatments were evaluated: an unfertilized control, urea at 40 and 80 kg N ha⁻ ¹ , OMF-N 1:2 at 40 and 80 kg N ha⁻ ¹ , and OMF-N 1:4 at 40 and 80 kg N ha⁻ ¹ . Nitrous oxide (N₂O) and methane (CH₄) fluxes were monitored using static chambers for 30 days following fertilization. CH₄ fluxes remained low and were frequently negative, indicating net soil CH₄ uptake on several sampling dates. N₂O emissions increase after N fertilization, with greater cumulative emissions in 2023 than in 2022. Compared with urea, OMF-N did not reduce cumulative N₂O emissions at equivalent N rates. Emission factors (EFs) averaged 0.31% in 2022 and 0.78% in 2023, both below the 1% IPCC default value. Forage accumulation (FA) during the gas monitoring period was greater with OMF-N ratios of 1:2 and 1:4 at 80 kg N ha⁻ ¹ than in the unfertilized control. NUE was unaffected by the fertilization strategy but was higher in 2022 than in 2023. Overall, OMF-N increased short-term forage accumulation at 80 kg N ha⁻ ¹ but provided no clear advantage over urea for N₂O mitigation or NUE under the tropical conditions evaluated in the Amazon biome.

Beef cattle farming in Brazil is predominantly based on pasture systems and faces challenges in the dry season due to the decrease in the quantity and quality of forage. To maintain productivity, intensive pasture finishing (IPF) is implemented, which requires the use of additives to ensure animal performance and rumen health. It is therefore essential to assess the economic viability of this practice. Thus, the present study aimed to identify which combination of additives provides the highest financial return in intensive pasture-based finishing systems for Nelore cattle in the Amazon biome. The research took place at Fazenda Gamada, Nova Canaã Norte - MT, for 120 days, with Mombaça grass pasture divided into 15 paddocks. The design was randomized, with five treatments and three replications: Lasalocid (control); Lasalocid + Actigen®; Lasalocid + ADV Fortuna LM; Lasalocid + Probios Precise®; and Lasalocid + LithoNutri®. The costs were evaluated according to the CONAB and IMEA standards. All the treatments resulted in positive economic viability. The highest net profits were obtained with Lasalocid and Lasalocid + ADV Fortuna LM, with profitability values of 8.4% and 8.8%, respectively. All the IFP additive combinations proved to be economically viable, with the L and LADV treatments being the most profitable.

This study aimed to evaluate the effects of different nutritional strategies on the intensification of beef cattle farming on pastures during the rainy season. Eighty male cattle (testers) were randomly allocated to 16 paddocks formed with Mombaça grass (Megathyrsus maximus), totaling five animals (testers) per paddock. The strategies consisted of two levels of concentrates (LC) [7 and 10 g.kg^-1 of body weight (BW)], i.e., low and high LC, and two protein sources (PS) with dried distillers’ grain with solubles (DDGS) and soybean meal (SBM) in a completely randomized design with a 2 × 2 factorial arrangement. The forage’s chemical, structural, and productive characteristics and the supplemented animals’ performance, productivity, and serum parameters were evaluated. The forage had the greatest height (P = 0.038) at the lowest LC; however, a greater leaf proportion (P = 0.049) and leaf: stem ratio (L:S) (P = 0.042) were observed when the highest LC was used. The animals receiving the highest LC had the highest supplement intake (P < 0.001) and a lower pasture intake (P = 0.001). The average daily gain (ADG) did not differ between the LC (P = 0.135) and PS (P = 0.190) groups (0.97 kg.day^-1). The LC used in the nutritional strategies did not affect the stocking rate (P = 0.272) or productivity (P = 0.986). Supplementation of 7 g.kg^-1 BW is recommended for intensive rearing of beef cattle during the rainy season, as it results in high gains at a relatively low cost. In addition, as there were no negative responses to the use of DDGS as a protein source in the supplement, it represents an alternative for replacing soybean meal in the formulations.

Pasture-based beef cattle production systems aim to maximize the interaction between forage and supplements to increase activity. In addition, supplementation and the use of food additives help optimize production efficiency and improve the use of additional nutrients. The aim of this study was to evaluate the effects of the use of additives in protein–energy supplements (PESs) on the intake, digestibility, and ruminal parameters of beef cattle raised on pasture in the rearing phase. Five male cattle were allocated to a 5 × 5 Latin square design, with five experimental periods and five treatments. The animals were kept under continuous grazing in individual paddocks of marandu palisadegrass (Urochloa brizantha cv. Marandu). The treatments consisted of a mineral mixture (MM) (0.080 kg/animal/day), PES (4.0 kg/animal/day), PES with monensin sodium (120 mg/animal/day), PES with functional oil (2500 mg/animal/day) and PES with active yeast (4000 mg/animal/day). PESs increased the total dry matter intake (DMI) (kg/day) and the DMI in terms of % body weight (%BW) and increased the intake of crude protein (CP) and the dry matter intake of digestible organic matter (DOM). The use of additives did not affect nutrient intake or digestibility. Compared with MM, the PES increased the concentrations of ruminal ammonia nitrogen and serum urea nitrogen. In addition, there was an increase in fecal nitrogen, retained nitrogen, microbial nitrogen synthesis and microbial efficiency. The use of monensin sodium, functional oil and active yeast in protein–energy supplements for beef cattle in pastures did not affect the nutritional parameters under the conditions observed in this study.

Knowledge about the decomposition of litter in signal grass pastures is still limited, especially in pastures managed under deferred grazing. Thus, we aimed to evaluate the chemical composition, carbon/nitrogen (C/N) ratio, and decomposition rate of litter in signal grass (Urochloa decumbens cv. Basilisk) pastures not fertilized with N (U0), fertilized with 50 kg·N·ha⁻¹ (U50), fertilized with 100 kg·N·ha⁻¹ (U100), and intercropped with calopo (Calopogonium mucunoides Desv.) (UC), managed under deferred grazing at different incubation times for two experimental periods (2017–2018 and 2018–2019). Data were analyzed using a randomized block experimental design with four management systems and two blocks, each containing two replicates per treatment. Nitrogen sources increased the N concentrations in the litter before incubation. Nitrogen concentrations in the incubated litter were affected by the incubation times and periods, increasing over time, mainly for U50 and U100. U100 litter samples exhibited higher acid detergent insoluble nitrogen (ADIN) levels than the U0 litter samples only in period 2. Notably, the C/N ratio did not differ with the different management systems; however, it decreased with increasing incubation times and periods, with final values of 24:1 and 26:1 in periods 1 and 2, respectively. Overall, litter samples from pastures fertilized with chemical or biological N sources exhibited higher N concentrations, but their incubated litter samples exhibited higher ADIN concentrations. However, management systems did not affect C/N ratios and no differences in litter biomass decomposition were observed among the systems, possibly due to the grazing period occurring prior to litter sampling.

The objective of this study was to evaluate the effect of different nutritional strategies on the intensification of beef cattle farming on pastures during the dry period of the year. Eighty male cattle (testers) were randomly allocated to 16 paddocks formed with Mombaça grass (Megathyrsus maximus), totaling five animals (testers) per paddock. The strategies consisted of two LCs [10 and 16.7 g·kg−1 body weight (BW)] and two PSs with DDGS and SBM in a completely randomized design with a 2 × 2 factorial arrangement. The chemical, structural, and productive characteristics of the forage were evaluated, as well as the performance, productivity, and serum parameters of the supplemented animals. The forage presented a greater L:C (p = 0.033) and CP content (p = 0.007) when the lowest LC was used. Animals that received the highest LC had the highest supplement intake (p < 0.001) and the lowest pasture intake (p < 0.001). The nutritional strategy with an LC of 16.7 g·kg−1 of body weight (BW) resulted in a greater increase in total BW, i.e., 200 kg·BW ha−1 more. Therefore, higher levels of concentrate ensure greater productivity for beef cattle grazing, and DDGS can replace SBM in supplements used in the intensive raising of beef cattle on pasture without compromising the performance and productivity of the animals.

The objective was to evaluate the effects of including high-protein distillers dried grains (HP-DDG; 430 g/CP) in supplements for beef cattle in an intensive finishing pasture system. Five Nellore bulls with an average body weight (BW) of 413.5 ± 32 kg were distributed in a 5 × 5 Latin square design. The animals were randomly allocated to Marandu palisade grass paddocks (Urochloa brizantha cv. Marandu), with 0.32 ha each. Protein-energy supplements were evaluated and formulated with different replacement levels (0, 250, 500, 750 and 1000 g/kg) of soybean meal (SBM) by HP-DDG. Supplements were offered once a day in the amount of 6.0 kg/animal. Replacing SBM with HP-DDG had no effect (p > 0.10) on the intake of total and pasture DM, OM, CP, NDFap, digestible organic matter (DOM), metabolizable protein and CP:DOM ratio. Total and pasture DM intake averaged 6.07 and 11.54 kg/day, respectively. Replacing SBM with HP-DDG reduces and increases, respectively, the intake of degradable (RDP) and undegradable (RUP) protein in the rumen (p < 0.10) with a consequent linear reduction in ruminal ammonia concentration (RAN), nitrogen excretion in urine and serum N concentration (SUN) (p < 0.10). In supplements offered in the amount of 6.0 kg animal/day, SBM can be completely replaced by HP-DDG.

The objective of this work was to evaluate the digestibility and kinetic parameters of silages of commercial and experimental sorghum genotypes grown in a crop in amazon biome to identify materials that present the best performance. The experiment was carried out in Sinop/MT with silages from 15 genotypes to evaluate gas production and in vitro digestibility and energy estimation, including BRS 658, BRS 659, Volumax, BRS Ponta Negra, 15F30005, 15F30006, BRS 511, CMSXS 5027, 5030, 5043, 5045, BRS 716, AGRI-002E, 201934B008 and CMSXS 7501. Gas production, pH, ammonia-N, and in vitro digestibility analyses were carried out, in addition to energy estimation using equations. The silages of materials with the highest gas production and digestibility were forage because they have a greater amount of digestible carbohydrates. On the other hand, the biomass and saccharine standard biomass presented lower performance because they have a higher concentration of lignin and structural carbohydrates in their composition. For pH and ammonium-N, there was no difference between treatments. The greatest digestibility and energy potential come from the genotypes BRS 658, BRS 659 Volumax, 15F30006, CMSXS 5027, and CMSXS 5030, making the last three capable of commercial launch and use in the production of silage in animal feed.

Objetivou-se avaliar as características morfogênicas, estruturais e químicas do capim-braquiária (Urochloa decumbens) consorciado com amendoim forrageiro (Arachis pintoi) em três espaçamentos (40, 50 e 60 cm) e em duas alturas residuais pós-pastejo (5 e 15 cm). O experimento foi conduzido em delineamento em blocos casualizados, em esquema fatorial (3 x 2), com quatro repetições. As características estruturais e morfogênicas foram consideradas em esquema fatorial (3 × 2) + 1 (um tratamento adicional de capim-braquiária em monocultivo). Foram avaliadas as características químicas amostradas por corte e via pastejo simulado. O capim-braquiária apresentou o maior teor de proteína bruta (PB) a 5 cm, enquanto o amendoim forrageiro apresentou o maior teor de PB a 15 cm, no primeiro ano, no entanto, não houve diferença no segundo ano. Comparado à monocultura, o consórcio resultou em menor tamanho final do colmo, maior número de folhas vivas e aumento nas seguintes métricas: taxa de alongamento da folha, tamanho final da folha e duração da vida da folha, mais consistentemente com altura residual de 5 cm, no segundo ano. O amendoim forrageiro melhorou as características morfogênicas e estruturais do capim-braquiária, principalmente quando manejado a 5 cm de altura pós-pastejo, independentemente do espaçamento entre linhas.

This study aimed to evaluate the accumulation, structural characteristics, and chemical composition of deferred signal-grass pastures that were subjected to four treatments: without nitrogen fertilization, intercropped with calopo (Calopogonium mucunoides), and fertilized with urea N (50 kg ha⁻¹ and 100 kg ha⁻¹) for 2 years. The design was in randomized blocks, with two blocks and two repetitions of each treatment per block. There were effects of the interaction between treatment and year on green dry mass, forage accumulation, density of vegetative tillers, and crude protein content (simulated grazing). The effects of the treatments on the height, falling index, green dry mass/dead dry mass ratio, number of dead, live and total tillers, and crude protein content (direct cutting) were also observed. Signal-grass–calopo-intercropping ensured adequate mass and forage accumulation and crude protein content equivalent to those of fertilized pastures. In addition, the intercropped pasture showed a higher percentage of leaves and a higher crude protein content compared with those for the other treatments (simulated grazing). The green dry mass/dead dry mass ratio was highest in the intercropped pasture and was equivalent to only that of the pasture fertilized with a low dose of nitrogen. Therefore, signal-grass–calopo-intercropping may be recommended for deferment.