Effects of Protein Feed Ingredients on Odor and Carbon Emission Mitigation in Nursery Pigs: An In Vitro Fermentation Study

Modern livestock farming is continuously expanding in scale and intensifying, placing significant pressure on the environment, about odor emissions. Therefore, effectively managing and reducing odor emissions from pig farms has become crucial for the sustainable development of the livestock husbandry. Numerous studies showed that the primary sources of odor in pig farms were the microbial fermentation of manure, wastewater, and feed residues. Recent studies focused on reducing odor emissions by employing new mechanical manure-cleaning methods and deodorants sprays onto pig manure. For example, air treatment measures were used to reduce odor emissions from pig houses, such as wet scrubber and deorizing spray net , as well as manure management strategies including semi-permeable membrane covering, reactor composting, slurry covering, and slurry acidification. Additionally, microbial agents, such as a mixture of Bacillus licheniformis, Pseudomonas denitrificans, and Saccharomyces cerevisiae, were sprayed onto manure to achieve deodorization . However, studies focusing on controlling odor emissions by selecting feed ingredients to optimize feed formulas were limited.