Innovative Cattle Feed Additive Shows 81% Reduction in Nitrogen Emissions

An interdisciplinary research team involving the Research Institute of Farm Animal Biology (FBN) in Dummerstorf, alongside the Universities of Rostock, Munich, and Vienna, has unveiled a groundbreaking discovery that willow leaves can significantly reduce nitrogen emissions from cattle farming by up to 81%. This innovative approach presents a promising avenue for enhancing the sustainability of pasture farming, which is traditionally associated with high levels of ammonia and nitrous oxide emissions.

The study, published in the peer-reviewed journal *Agriculture, Ecosystems & Environment* on June 17, 2025, emphasizes the pressing need for sustainable agricultural practices, as approximately 80% of global ammonia emissions and 81% of nitrous oxide emissions stem from agricultural activities (Müller-Kiedrowski et al., 2025). These emissions significantly contribute to environmental degradation, with nitrous oxide possessing a global warming potential approximately 300 times greater than carbon dioxide, persisting in the atmosphere for around 150 years.

PD Dr. Björn Kuhla, head of the focus topic "Farming animals in sustainable resource cycles" at FBN, remarked, "If we want to preserve pasture farming as an animal-friendly and sustainable form of livestock farming, we must also get a grip on its environmental impact." The traditional methods of mitigating these emissions have proven ineffective, particularly in pasture systems where livestock excretion occurs directly on grazing land.

The research team explored the influence of salicin, a precursor molecule found in willow leaves, on nitrogen metabolism in cattle. Their findings revealed that cattle fed with willow leaves exhibited a remarkable 14% reduction in ammonia and a staggering 81% reduction in nitrous oxide emissions over a 48-hour period when compared to a control group. This reduction is attributed not only to salicylic acid but also to other bioactive compounds present in the leaves.

Historically, willows (genus *Salix*) have been utilized as both medicinal and fodder plants in various cultures, including New Zealand and North America. However, their potential as a feed additive to combat nitrogen loss in livestock is a novel application. Kuhla noted, "Willow foliage is a locally available, renewable raw material that is particularly suitable as a natural feed supplement for pasture farming—where other solutions fail."

Despite the promising results, further field trials are necessary to ascertain the efficacy of willow leaves under real farming conditions, taking into account variables such as feed intake, soil type, climate, and microbial activity. The researchers are also investigating other deciduous species, such as poplar, which exhibit similar nitrogen-reducing properties.

The long-term vision includes the development of silvopastoral systems—integrating pasture with wooded areas—where plants like willows could provide feed directly on the pasture, enhance the microclimate, and further mitigate emissions. Additionally, the researchers are testing the application of willow leaf extracts in stable manure or slurry to evaluate their impact on reducing nitrogen emissions in waste management.

In conclusion, the innovative use of willow leaves as a natural feed additive represents a significant step towards making cattle farming more environmentally sustainable. As this research progresses, the implications for agriculture could be profound, potentially leading to reduced nitrogen emissions and a lesser ecological footprint in livestock farming. The findings underscore the importance of interdisciplinary collaboration in addressing global environmental challenges.