Efficacy of tannins as silage additives to inhibit deamination process during ensiling: a meta-analysis and <i>in silico</i> approach.
Tannins show promise in reducing protein degradation during ensiling, but further experimental validation is needed to confirm their practical benefits.
Where it sits
this study against the rest of the nad+ (nicotinamide adenine dinucleotide) corpusSummary and findings
This study evaluated the efficacy of tannins as silage additives to inhibit protein deamination during ensiling through a meta-analysis and in silico approach. The meta-analysis showed significant reductions in NH₃-N, non-protein nitrogen, and soluble nitrogen concentrations with tannin supplementation. Molecular docking simulations identified terflavin B as the most stable ligand with the lowest binding free energy.
Abstract
Ensiling, the anaerobic preservation of forage, is widely used to ensure year-round feed availability. However, high-protein forages are prone to protein degradation and deamination during ensiling, leading to ammonia formation and reduced feed quality. This study evaluated the efficacy of tannins as natural additives for inhibiting protein deamination using a meta-analysis of published studies, complemented by an <i>in silico</i> approach. Because tannins possess protein-binding properties, their potential role in inhibiting deamination was further examined through interactions with glutamate dehydrogenase (GDH), an enzyme associated with deamination pathways in <i>Clostridium</i> species commonly found in silage. A random-effects meta-analysis was conducted using OpenMEE, and molecular docking simulations were performed using AutoDock4 to predict the binding affinity of tannin-derived compounds toward GDH. The meta-analysis showed that tannin supplementation significantly (p < 0.001) reduced NH₃-N, non-protein nitrogen (NPN), and soluble nitrogen concentrations, while also lowering butyric acid concentration, indicating improved silage quality. Meta-regression analysis further demonstrated a linear decrease in ammonia concentration with increasing tannin levels (equation: -0.842 - 0.048 × level). MM/GBSA analysis further suggested that terflavin B was the most stable ligand, with the lowest binding free energy (-51.06 kcal/mol), followed by corilagin (-43.11 kcal/mol) and punicalin (-34.48 kcal/mol), indicating strong interactions with the GDH active site. In addition, bioavailability and toxicity prediction indicated generally favorable safety characteristics of these tannin-derived compounds. Overall, the integrated findings support the potential of tannins as bioactive agents for reducing protein degradation in silage, thereby improving nutrient preservation and feed quality during storage.
Background
The study addresses the challenge of protein degradation and ammonia formation during the ensiling of high-protein forages, which can reduce feed quality. Tannins, known for their protein-binding properties, are proposed as natural additives to inhibit deamination processes. This research is important as it explores a potential method to improve nutrient preservation and feed quality in silage.
Methods
The study utilized a random-effects meta-analysis of published studies to evaluate the efficacy of tannins in reducing protein degradation during ensiling. OpenMEE software was used for the meta-analysis, and molecular docking simulations were conducted using AutoDock4 to assess the binding affinity of tannin-derived compounds with glutamate dehydrogenase (GDH). The study also included bioavailability and toxicity predictions for these compounds.
Results
The meta-analysis demonstrated that tannin supplementation significantly reduced NH₃-N, non-protein nitrogen, and soluble nitrogen concentrations (p < 0.001), indicating improved silage quality. The meta-regression analysis showed a linear decrease in ammonia concentration with increasing tannin levels. Molecular docking simulations identified terflavin B as the most stable ligand with a binding free energy of -51.06 kcal/mol, suggesting strong interactions with GDH. Bioavailability and toxicity predictions indicated favorable safety profiles for the tannin-derived compounds.
Interpretation
The findings suggest that tannins could be effective in reducing protein degradation in silage, potentially improving feed quality. However, the reliance on meta-analysis and in silico methods limits the direct applicability of the results to real-world settings. While the effect sizes are statistically significant, further experimental validation is needed to confirm the practical benefits of tannin supplementation in silage.
Key findings
- Tannin supplementation significantly reduced NH₃-N, NPN, and soluble nitrogen concentrations (p < 0.001).
- Butyric acid concentration was lowered, indicating improved silage quality.
- Meta-regression showed a linear decrease in ammonia concentration with increasing tannin levels (equation: -0.842 - 0.048 × level).
- Terflavin B had the lowest binding free energy (-51.06 kcal/mol) among tannin-derived compounds.
- Bioavailability and toxicity predictions indicated generally favorable safety characteristics.
Limitations
- Meta-analysis and in silico approach only
- No direct experimental validation
- Potential variability in real-world applications
- Findings based on published studies