Chestnut tannins in lamb nutrition: Balancing protein utilization and feed efficiency in sustainable fattening systems

Tannins are complex plant-derived polyphenols that are increasingly being investigated in ruminant nutrition due to their protein binding capacity, bioactive properties and potential to support sustainable production goals. They can modulate fermentation in the rumen, reduce protein degradation and alter the dynamics of nutrient absorption dynamics - but their dual role as functional and potentially antinutritive agents requires differentiated evaluation. This paper discusses the broader functional importance of tannins in ruminant diets based on a comprehensive literature review, focussing on their mechanisms of action, influence on digestibility, animal performance and metabolic responses. Within this framework, a practical model of lamb fattening will be analysed to investigate the controlled use of chestnut tannins under different feeding conditions and protein balances. The model serves to illustrate the general challenges of implementing tannin research in commercial feeding systems. The importance of dosage, tannin type, feed matrix and animal-specific factors that determine efficacy and safety is emphasised. Whilst the integration of tannins offers promising routes to nitrogen efficiency and reduced environmental impact, practical implementation requires a clear understanding of the economic trade-offs and variability at farm level. The findings presented will serve as a basis for future research designs and practical implementation strategies for plant additives in small ruminant diets.