Willow (Salix spp): The potential of a tannin-rich tree fodder to reduce ammonia emissions and improve productivity of dairy cattle

As the global demand for animal products is rising, these should be produced with less environmental impact. Climate-induced shifts increase feed costs due to increased need for resources (land and water). However, protein is poorly utilized by ruminant livestock and 20-35% of ingested N is excreted via urine and faeces. Therefore, alternative feeds associated with reduce competition for land and constitute industry by-products, are required. Willow (Salix sp.) fodder is used in biofuel production but leaves and branches, up to 18mm diameter, are considered as waste. Willow fodder tree has a high protein content (well above from that required for livestock maintenance) and contains condensed tannins (CT) which bind to proteins, reduce their ruminal degradation and shift N excretion from urine to faeces (environmentally friendly N form).
The aim of this project is to evaluate the nutritive value of willow and assess its potential to improve N use efficiency in dairy cows; by also assessing its impact on milk quality. This will be achieved via the following studies:
1. In vitro assessment of the effects of willow CT on rumen digestive capacity.
2. Optimization of the ensiling process.
3. Assessment of the effect of WS inclusion in the diet of dairy cow and ammonia emissions.
4. Reveal how rumen microbes influence metabolic pathways related to N use efficiency and milk quality.