Greenhouse gas emissions and nutrient flows during housing and manure storage of Belgian Blue cattle

Mankind is concerned about its influence on the environment. In this context, beef production systems, are facing challenges especially to reduce their greenhouse gas (GHG) emissions. In this respect, current emission levels and management strategies allowing their reduction have to be specified. The target of this thesis was to produce specific local values and to test the influence of factors such as barn type (tied stalls and deep litter), cattle diet and manure management strategies (manure removal frequency in deep litter systems) on GHG emissions by beef cattle and their manures in the barn but also during the storage of these manures. Nutrients (nitrogen, phosphorus and potassium) flows were also quantified for environmental and agronomical purposes. By in vivo experiments, it was emphasized that (1) cattle diet, manure management and barn type are driving factors of GHG emissions and nutrient losses from cattle husbandry; (2) the GHG emissions from farmyard manure during its storage can contribute significantly to the global emissions from cattle husbandry; (3) ambient conditions during farmyard manure storage were key factors for controlling these emissions and losses; (4) the farmyard manure management system with the highest straw supply rate showed the highest nitrogen and carbon losses and the highest levels of GHG emissions. In the future, the evaluation of the effects at earlier or later stages (e.g. feed production, emissions due to manure spreading, impact on soil C sequestration, etc.), of the factors tested should allow the quantification of the environmental impact and efficiency of the whole system.(AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 202