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Changes in VOCs Emissions from Fecal Manure throughout the Life Cycle of Beef Cattle
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: 2007 ASAE Annual Meeting 074003.(doi:10.13031/2013.23049)
Authors: Yael Laor, Ariel Shabtay, Uzi Ravid, Rima Baybikov, Harel Eitam
Keywords: Odor, Beef cattle, Diet formulation, Life cycle, VOC, SPME
Odors emitted from animal feeding operations are complex mixtures of NH3, H2S and volatile organic compounds (VOCs). It is widely recognized that diet composition as well as manure storage conditions affect odor characteristics. Throughout cattle life cycle, distinctly different diets are formulated to meet the changing needs for growth and development. Here we followed VOCs emissions from fecal manure of 6 Holstein calves at five stages throughout their life cycle: I. One-week age (Diet formulation: Milk powder, 23% crude protein; CP); II. 7-weeks age (Milk powder and suckling mix ration, 16-23% CP); III. 10.5-weeks age (Suckling mix ration, 16% CP); IV. 24-weeks and V. 36-weeks age (both fattening mix ration, 13.9% CP). Fresh fecal samples were incubated under aerobic or anaerobic conditions for 21 days. VOCs were analyzed using solid phase microextraction followed by GC-MS. Levels of VOCs were compared from their peak area counts. The results show that fresh manure from stage-I had relatively low levels of S-compounds but high levels of VFAs and their esters. Opposite trends appeared in stage-II. After incubation under aerobic conditions, levels of S-compounds, volatile fatty acids (VFAs), phenol and indole from all stages were reduced substantially. In contrast, storage under anaerobic conditions produces malodorous VOCs, mainly VFAs, dimethyl disulfide, dimethyl trisulfide, phenol and skatole. The results demonstrate that life stage in combination with manure storage conditions critically affect odor emissions from beef fattening operations. Incorporation of life stages in odor models should improve annoyance predictions.(Download PDF) (Export to EndNotes)