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Food security, sustainability of food production, and greenhouse gas (GHG) production of ruminant livestock are topics that generate scrutiny and debates worldwide. In a scenario of increasing human population and concerns with climate change, it is necessary to increase animal-derived food in sustainable operations. Grazing systems are crucial for ruminant production worldwide, and in the tropics, well-managed grasslands can provide sustainable intensification of this activity. In these regions, production often relies on grass monoculture managed extensively, a practice that commonly has led to the occurrence of degraded soils, limited animal productivity, and increased intensity of GHG emissions. Silvopastoralism is a practice that promotes several ecosystem services, showing potential to maintain soil quality while reducing the environmental impacts of ruminant production. These systems also have the potential to improve animal productive performance and reduce GHG emissions. The review was guided by a search in the Web of Science database using population terms and refined by document type (Article) and language (English OR Portuguese) following PRISMA protocol. Infographics were created using the Bibliometrix package in R software (version 4.3.2), and a specific topic on Tithonia diversifolia (Hemsl.) A. Gray was explored to demonstrate the importance of this forage resource for tropical silvopastoral systems and its potential contribution to food security. The T. diversifolia shrub is widely distributed in Latin America and tropical regions and presents several characteristics that make it a good option for silvopastoral systems. Focusing on the tropics, our objectives were to present one literature review addressing the role of grazing ruminant production towards the current climate change and food security challenges. Additionally, we aimed to explore the state of knowledge on silvopastoral systems and the use of T. diversifolia, presenting their potential to cope with this scenario of increased concerns with the sustainability of human activities.

Considering the hypothesis that density and dry matter (DM) concentration may be used as indicators of silage nutritional quality, the aim of the present study was to determine density and maturation stage (i.e. DM concentration) of corn silages under farm conditions in Brazil, establishing relationships between density and physical and chemical characteristics. In a completely randomized design, 20 bunkers of corn silage, each from a different farm, were used for data collection. Using a coring machine, 5 samples of silage were extracted from an exposed face of each silo and samples were analyzed for density of compaction, plus concentrations of DM, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), total digestible nutrients (TDN), total carbohydrate (TC), non-fiber carbohydrate (NFC) and starch (STA), as well as electrical conductivity. There was significant variation in many of the parameters measured with the greatest variation in density on a natural matter basis. Negative correlations were observed between percentages of DM, NDF and ADF in the silage and silage density on a natural matter basis (P

Several methodologies have been tested to evaluate silage density, with direct methods most popular, whereas indirect methods that can be used under field conditions are still in development and improvement stages. This study aimed to establish relationships between estimates of maize silage density determined using a direct and an indirect method, in an endeavor to provide an alternative to direct measurement for use in the field. Measurements were performed on maize silage in 14 silos. The direct method involved the use of a metal cylinder with a saw-tooth cutting edge attached to a chainsaw to extract a core of silage. Density of the silage was determined taking into consideration the cylinder volume and dry matter weight of silage removed at 5 points on the silage face. With the indirect method, a digital penetrometer was used to estimate silage density by measuring the penetration resistance at 2 points adjacent to the spots where the silage cores were taken, i.e. 10 readings per silo. Values of penetration resistance (measured in MPa) were correlated with the values of silage mass (kg/m3) obtained by direct measurement through polynomial regression analysis. A positive quadratic relationship was observed between penetration resistance and silage density for both natural matter and dry matter (R² = 0.57 and R² = 0.80, respectively), showing that the penetrometer was a reasonably reliable and simple indirect method to determine the density of dry matter in maize silage. Further testing of the machine on other silos is needed to verify these results. Keywords: Ensiled matter, penetrometer, resistance, silos evaluation.