The present review examines the factors and variables that should be considered to obtain, design, and evaluate EFEs that might enhance ruminal NDF degradability. Different combinations of words were introduced in Google Scholar, then scientific articles were examined and included if the reported factors and variables addressed the objective of this review. One-hundred-and-sixteen articles were included. The fungal strains and culture media used to grow white-rot fungi induced the production of specific isoforms of cellulases and xylanases; therefore, EFE products for ruminant feed applications should be obtained in cultures that include the high-fibrous forages used in the diets of those animals. Additionally, the temperature, pH, osmolarity conditions, and EFE synergisms and interactions with ruminal microbiota and endogenous fibrolytic enzymes should be considered. More consistent results have been observed in studies that correlate the cellulase-to-xylanase ratio with ruminant productive behavior. EFE protection (immobilization) allows researchers to obtain enzymatic products that may act under ruminal pH and temperature conditions. It is possible to generate multi-enzyme cocktails that act at different times, re-associate enzymes, and simulate natural protective structures such as cellulosomes. Some EFEs could consistently improve ruminal NDF degradability if we consider fungal cultures and ruminal environmental conditions variables, and include biotechnological tools that might be useful to design novel enzymatic products.

The objective was to review the potential effects of adding anthocyanin delphinidin-3-O-sambubioside (DOS) and cyanidin-3-O-sambubioside (COS) of HS in animal diets. One hundred and four scientific articles published before 2021 in clinics, pharmacology, nutrition, and animal production were included. The grains/concentrate, metabolic exigency, and caloric stress contribute to increasing the reactive oxygen species (ROS). COS and DOS have antioxidant, antibacterial, antiviral, and anthelmintic activities. In the rumen, anthocyanin might obtain interactions and/or synergisms with substrates, microorganisms, and enzymes which could affect the fiber degradability and decrease potential methane (CH₄) emissions; since anthocyanin interferes with ruminal fatty acids biohydrogenation (BH), they can increase the n-3 and n-6 polyunsaturated fatty acids (PUFA), linoleic acid (LA), and conjugated linoleic acid (CLA) in milk and meat, as well as improving their quality. Anthocyanins reduce plasma oxidation and can be deposited in milk and meat, increasing antioxidant activities. Therefore, the reduction of the oxidation of fats and proteins improves shelf-life. Although studies in ruminants are required, COS and DOS act as inhibitors of the angiotensin-converting enzyme (ACEi) and rennin expression, regulating the homeostatic control and possibly the milk yield and body weight. By-products of HS contain polyphenols as calyces with positive effects on the average daily gain and fat meat quality.

Utilization of maize stover to the production of meat and milk and saving the grains for human consumption would be one strategy for the optimal usage of resources. Variance and tendency analyses were applied to find the optimal nitrogen (N) fertilization dose (0, 100, 145, 190, 240, and 290 kg/ha) for forage (F), stover (S), cob (C), and grain (G) yields, as well as the optimal grain-to-forage, cob-to-forage, and cob-to-stover ratios (G:F, C:F, and C:S, respectively). The study was performed in central Mexico (20.691389° N and −101.259722° W, 1740 m a.m.s.l.; Cwa (Köppen), 699 mm annual precipitation; alluvial soils). N-190 and N-240 improved the individual yields and ratios the most. Linear and quadratic models for CDM, GDM, and G:F ratio had coefficients of determination (R²) of 0.20–0.46 (p < 0.03). Cubic showed R² = 0.30–0.72 (p < 0.02), and the best models were for CDM, GDM, and the G:F, C:F, and C:S DM ratios (R² = 0.60–0.72; p < 0.0002). Neither SHB nor SDM negatively correlated with CDM or GDM (r = 0.23–0.48; p < 0.0001). Excess of N had negative effects on forage, stover, cobs, and grains yields, but optimal N fertilization increased the proportion of the G:F, C:F, and C:S ratios, as well as the SHB and SDM yields, without negative effects on grain production.