Enteric methane (CH₄) emissions from ruminants contribute to agricultural greenhouse gas emissions and represent a loss of dietary energy that could otherwise support animal production. Dried distillers’ grains with solubles (DDGSs) have received increasing attention as an alternative feed ingredient because of their nutritional value and potential to influence rumen fermentation, nutrient utilization, and CH₄ emissions. This systematic review evaluated the effects of DDGSs on enteric CH₄ emissions and nutrient utilization in ruminant diets. Literature searches were conducted in Google Scholar, Scopus, and Web of Science for studies published between 2010 and 2025. Following PRISMA guidelines and using the SYRCLE risk of bias tool, 17 studies, comprising 9 in vivo, 5 in vitro, and 3 integrated in vivo–in vitro studies, were included in the qualitative synthesis. The DDGS supplementation did not consistently reduce absolute CH₄ production, although reductions in CH₄ yield and emission intensity were more frequently reported. Moderate inclusion levels (up to 20% of diet dry matter) were frequently associated with improved nutrient utilization, feed efficiency, and animal performance, although these responses varied among studies. Reductions in CH₄ yield and emission intensity were more commonly reported than reductions in absolute CH₄ production. Higher inclusion levels (>30% of diet dry matter) produced more variable responses and were often associated with reduced fiber digestibility. In conclusion, the available evidence suggests that DDGS may act as a dietary modifier capable of improving nutrient utilization and production efficiency under appropriate dietary conditions; however, responses remain dependent on inclusion level, DDGS source, basal diet composition, and production system.

This systematic review synthesized evidence on the effects of marine macroalgae supplementation on enteric methane (CH₄) emissions, rumen fermentation, nutrient utilization, animal performance, animal health, and product quality in ruminants. Google Scholar, Scopus, Web of Science, and CAB Abstracts with Full Text were systematically searched for peer-reviewed in vivo studies published between January 2015 and 30 July 2026. Following PRISMA 2020 procedures, 25 studies were included in the qualitative synthesis, and risk of bias was assessed using the SYRCLE tool. Red macroalgae, particularly Asparagopsis spp., produced the greatest reductions in CH₄ production, yield, and intensity, although responses varied with species, inclusion level, basal diet, animal species, and supplementation duration. Brown macroalgae produced less consistent CH₄ responses, while evidence for green macroalgae was limited. Several studies reported reduced acetate and increased propionate, whereas effects on nutrient digestibility varied. Animal performance was generally maintained at lower inclusion levels, but higher inclusion levels of some red macroalgae reduced dry matter intake and, in some studies, milk production. Some seaweed treatments increased iodine and bromine concentrations in milk and other biological matrices, highlighting the importance of residue monitoring. The evidence was limited by methodological and biological heterogeneity, small sample sizes, short experimental periods, variation in macroalgal composition and CH₄-measurement methods, geographical concentration, and limited long-term evidence. Marine macroalgae shows potential as functional feed additives for enteric CH₄ mitigation, but the evidence does not support a universally optimal inclusion rate. Longer-term, adequately powered in vivo studies are needed to establish species-specific dose-response relationships, persistence of CH₄ mitigation, food-safety requirements, and economic feasibility.

The objective of this review was the assessment of the effect of flavonoid sources on nutrient intake and digestibility, rumen fermentation, growth performance, milk production and endoparasites in ruminant production. The increasing human population is creating a greater demand for animal products to meet the protein needs. However, an increase in animal production is likely to force the overuse of synthetic antibiotics, which may intensify drug‐resistant pathogens. As a solution, there is a need to discover natural feed additives to improve environmental harmlessness, health and performance in ruminant production. This is because ruminants produce methane and suffer from infections such as gastrointestinal nematodes and mastitis that limit animal performance. Hence, there is a need to identify feed additives that decrease this gas without limiting nutrient utilization and animal performance. Flavonoid dietary inclusion is a potential solution to this challenge in ruminant production and has received research attention. However, there is a preliminary understanding of the effect of inclusion on effectiveness in decreasing methane production and pathogens, improving rumen fermentation, milk production and growth performance in ruminants. Therefore, there is a need for the identification of the effect of flavonoid inclusion on the abovementioned parameters for the detection of research limitations requiring assessment for the identification of a single flavonoid inclusion with a holistic effect on the production parameters of ruminants.

Heat stress (HS) is a major constraint to poultry productivity, especially in regions experiencing high environmental temperatures. It disrupts thermoregulation, reduces feed intake and impairs growth, egg production, reproductive performance, intestinal integrity and immune function. Plant‐based nutraceuticals have therefore attracted interest as complementary interventions for improving poultry resilience to thermal stress. This narrative review was designed to synthesise evidence on the physiological effects of HS and the potential of phytogenic nutraceuticals to alleviate heat‐induced dysfunction in poultry. The narrative review was created by identifying relevant literature through targeted searches of Google Scholar, Scopus and Web of Science using terms related to heat exposure, poultry species, nutraceutical interventions and physiological or productive responses. Reference lists were also examined to identify additional studies. No strict publication‐year restriction was applied, and peer‐reviewed empirical and review articles relevant to the objectives were considered. The reviewed evidence suggests that bioactive compounds from botanical sources such as Moringa oleifera , Curcuma longa , Zingiber officinale and Lippia species may strengthen antioxidant defences, regulate endocrine and immune responses, protect intestinal integrity and support productive and reproductive performance under HS. However, their effectiveness varies with plant source, phytochemical composition, active‐compound concentration, inclusion level, bioavailability, poultry type and heat‐exposure conditions. Wider application is constrained by inconsistent product composition, limited dose–response information, uncertainties regarding long‐term safety and insufficient validation under commercial production conditions. Future research should standardise phytochemical characterisation, extraction and processing methods, evaluate bioavailability and apply transcriptomics, metabolomics and microbiome analyses to clarify mechanisms of action. These advances could support the scientific validation of indigenous plants and their development into accessible, region‐specific nutraceutical interventions for climate‐smart poultry production.