Impact of Mixed Rations on Rumen Fermentation, Microbial Activity and Animal Performance: Enhancing Livestock Health and Productivity—Invited Review

Feeding a balanced diet such as total mixed ration (TMR) is a widely adopted feeding strategy providing a uniformly blended diet of roughages, concentrates, and supplements that enhances ruminant productivity by optimizing nutrient utilization, stabilizing rumen fermentation, and improving microbial activity. Scientific studies have confirmed that TMR increases dry matter intake (DMI), milk yield, and growth performance in dairy and beef cattle, as well as in sheep and goats. TMR’s advantages include consistent feed quality, reduced selective feeding, and improved feed efficiency. A key benefit of TMR is its ability to promote the production of volatile fatty acids (VFAs), which are the primary energy source for ruminants, particularly propionate. This enhances energy metabolism, resulting in higher carcass yields, increased milk production, and economic benefits compared to conventional or supplementary feeding systems. However, TMR feeding is also susceptible to mycotoxin contamination (e.g., aflatoxins, zearalenone), potential effects on methane emissions, and the need for precise formulation to maintain consistency and optimise profitability. Prevention and good practices, including routine inspection of feed for pathogens and vulnerable ingredients, as well as careful management of particle size and forage-to-concentrate ratios, are crucial in preventing subacute ruminal acidosis (SARA) and the development of other subclinical diseases. Mycotoxin binders, such as hydrated sodium calcium aluminosilicate, can also reduce mycotoxin absorption. Another advantage of practicing TMR is that it can support sustainable farming by integrating agro-industrial byproducts, which minimises environmental impact. In conclusion, TMR is a widely adopted feeding strategy that significantly enhances ruminant productivity by optimizing nutrient utilization, stabilizing rumen fermentation, and improving microbial activity, leading to increased dry matter intake, milk yield, and growth performance. It offers key benefits such as consistent feed quality, reduced selective feeding, improved feed efficiency, and enhanced energy metabolism, providing economic advantages and supporting sustainable farming through agro-industrial byproduct integration. However, its implementation requires careful management to mitigate risks, including mycotoxin contamination, potential impacts on methane emissions, and digestive issues like SARA if formulation is not precise. Therefore, for sustainable production, future research should focus on optimizing TMR formulations with alternative ingredients (e.g., agro-industrial byproducts) and precision feeding strategies to enhance livestock health and animal productivity while minimizing environmental impacts.