Ammonia and greenhouse gas emissions from straw-based deep litter systems for dairy cattle fed with contrasting diets
Résumé
The objective of the study is to acquire new knowledge about greenhouse gases and NH3 emissions at the barn level for dairy cows on a straw-based deep litter and fed contrasting diets: a grass-based (fresh and hay, GD) and a maize-based diet (silage and concentrate, MD). Two groups of three Holstein dairy cows in late lactation were housed in two closed and controlled mechanically ventilated rooms, and kept on a straw-based deep litter accumulated under the animals during four weeks. Individual milk yields and dry matter (DM) intake were recorded daily. H2O, NH3, CO2, CH4 and N2O emissions were measured continuously with an infrared photo-acoustic gas analyzer. The diet clearly affected GHG and ammonia emissions. The MD treatment involved higher CH4 emissions mainly because of a higher DM intake while the GD treatment caused greater emissions of ammonia due the higher diet protein content.