Among the alternatives identified as capable of making livestock farming a more efficient activity and reducing its environmental impact, the use of feeds with high digestibility and the use of non-conventional fodder species can be highlighted. Tithonia diversifolia (Hemsl.) A. Gray (TD) has already gained attention as a feed for ruminants. Nonetheless, there has been little discussion about the impacts of this plant on the rumen dynamics that lead to better animal performance. The aim of this study was to assess how increasing levels of TD could affect ruminal microbial biomass synthesis, degradability, and in vitro gas production (IVGP) of diets. Four diets were evaluated: a control diet (TD0: 400 g kg⁻¹ soybean meal and maize grain, and 600 g kg⁻¹ Tifton 85 hay (Cynodon spp.)) and three increasing levels of TD (TD9: 90, TD27: 270, and TD45: 450 g kg⁻¹–dry matter basis) as a replacement for dietary roughage. A 96 h IVGP assay was carried out and five incubation times (2, 4, 10, 24, and 96 h) were used for degradability determination. Gas produced, methane (CH4), degradability of organic matter (IVDOM), short-chained fatty acid (SCFA) production, partitioning factor (PF), and microbial biomass (MB) were evaluated among treatments. There was no significant effect (p > 0.05) between TD inclusion and IVGP at most incubation times; only at 6 h of incubation did gas production increase linearly with TD inclusion (R² = 0.19; p < 0.05). TD inclusion had no effects on CH4. IVDOM increased linearly with TD inclusion at 6 and 10 h, with TD45 being more degradable than the control diet at 6 h only. There was a positive linear relationship (R² = 0.20; p < 0.05) between TD inclusion and PF. TD45 had significantly higher PF values than the control. MB also increased linearly (R² = 0.30; p < 0.05) with TD inclusion, and all diets with TD had significantly more MB than the control diet. The inclusion of TD at the levels used in this work was revealed to have a positive impact on microbial protein synthesis, which could be related to the higher microbial efficiency of increased substrate quality.

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.

The feasibility of unconventional feed for ruminants must be analyzed for appropriate use as sources of energy or protein that contribute to a sustainable production system addressing concerns about climate change, greenhouse gas emissions, and food security. The objective of this study was to evaluate the nutritive value of by-products including bean residue (BR), bean straw (BS), cassava bagasse (CB), corn straw (CS), orange bagasse (OB), peanut shell (PS), sugarcane bagasse (SB), soybean hull (SH), and sugarcane straw (SS). Chemical composition, in vitro degradability, and fermentative parameters were analyzed and subjected to multivariate and principal component analyses. Crude protein content was highly variable among by-products with BR and SH presenting the highest values (p < 0.001). These values did not differ between BR and SH, while the lowest values were observed in OB, PS, SB, SS, CS, and CB. Neutral detergent fiber content was higher in SB, PS, CS, and SS (p < 0.001), while greater in vitro degradability was found for CB, BR, OB, BS, and SH (p < 0.001). However, the in vitro gas production (p < 0.001) and total short-chain fatty acid concentration (p < 0.001) were higher in CB, BR, BS, and OB. Multivariate cluster analysis showed three distinct groups with the most degradable in group 1 followed by group 2. These results demonstrate that the by-products used in this study did not impair in vitro fermentation, and thus have the potential to be used in the diets of ruminants and to improve the sustainability of the livestock production sector.

• Forage-free diet with plant-based additive improved feed intake and growth in finishing cattle. • Ruminal health was maintained despite lower pH and microbiota shifts. • Forage-free diet was associated with reduced estimated methane intensity.