Reducing ammonia and GHG emissions from rabbit rearing through a feed additive produced from green urban residues

The present paper proposes a new strategy, based on the use of a new healthy animal diet additive obtained from urban biowaste, to reduce the environmental impact from livestock production. The diet supplement is a water soluble biopolymer (SB) obtained from urban gardening wastes. The paper reports the results of a case study in which 35 days old rabbits were fed a conventional diet as control and with a test diet made up of the conventional diet and 0.05-1 % SB. Urine and faeces were collected, stored for 18 days at room temperature to simulate farm storage, and the resulting gaseous emissions were analysed. The manure from the animals fed the 0.25 % SB diet produced significantly lowest emissions (p<0.05): e.g., 30 % less ammonia (NH3), 25 % less methane (CH4), 9 % less nitrous oxide (N2O), and 8 % less carbon dioxide (CO2) than the control group. The SB feeding strategy can be applied on farms of any size and does not lead to any extra costs for the farm, except for the negligible cost of 0.003-0.007 € kg-1 for the SB supplement that has to be add to the normal animal diet. Full implementation of the SB strategy at a European Union level could lead to global yearly reductions of 1.1 Mt NH3, 0.06 Mt N2O, 2.2 Mt CH4, 0.92 Gt CO2-eq. emissions. The relevance of these results at a European Union level is discussed and the perspectives of previous work are accounted for to demonstrate that SBs can be used as chemical specialities in the chemical industry and in agriculture. The implementation of SB production and application at an industrial and commercial level could lead to important environmental and socioeconomic benefits for several sectors of a biobased economy.