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This Article Full Text (PDF) All Versions of this Article: jas.2008-1357v1 87/5/1835    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shabtay, A. Articles by Laor, Y. Search for Related Content PubMed PubMed Citation Articles by Shabtay, A. Articles by Laor, Y.

Dynamics of offensive gas-phase odorants in fresh and aged feces throughout the development of beef cattle

¹ Agricultural Research Organization, Institute of Animal Science, Newe Ya'ar Research Center, Ramat Yishay, ISRAEL 30095 , ² Agricultural Research Organization, Institute of Plant Sciences, Newe Ya'ar Research Center, Ramat Yishay, ISRAEL 30095 ³ Agricultural Research Organization, Institute of Soil, Water and Environmental Sciences, Newe Ya'ar Research Center, Ramat Yishay, ISRAEL 30095

laor{at}agri.gov.il

Abstract

Livestock odors are largely caused by several groups of volatile organic compounds (VOCs), including sulfur containing compounds, volatile fatty acids (VFAs), phenols and indoles. Throughout the growth stages of cattle in nursery and feedlot, distinctly different diets are formulated to meet the animal's changing requirements. Because diet compositions as well as manure management are two major factors affecting odor emissions, it was assumed that changes in diet composition along calves' development would impact VOCs emissions from fresh and stored manure. In this study the dynamic of gas phase VOCs in feces from six Holstein-Friesian bull calves was followed at five ages: 1-5 weeks (stage-I), 6-8 weeks (stage-II, before weaning), 9-14 weeks (stage-III, after weaning) and 15-36 weeks (stage-IV and V). The crude protein (CP) content of the formulated diet decreased from 23.0% to 13.9%. Fresh feces samples were incubated either under aerobic or anaerobic conditions for 21 days. VOCs were analyzed from feces headspace using solid phase microextraction followed by GC-MS. Distinct changes in gas-phase VOCs were observed in fresh and aged feces from different ages of calves. Semi-quantitatively (based on comparative peak area counts), the following trends were observed: 1. S-compounds were the least dominant in fresh feces at the age of 2 weeks (stage-I) whereas VFA-esters were the most dominant. 2. At age of 7 weeks (stage-II), a week before calves weaning, feces seemed to be the most offensive presumably due of the difficulty to synchronize between animal's requirements and diet formulation during this stage of rapid development. 3. VOCs decreased during feces storage under aerobic conditions but significantly increased at all five life stages during storage under anaerobic conditions. This study demonstrates that life stage in combination with manure management affect odor emissions from beef fattening operations. Incorporation of calves' age and diet in odor modeling could improve annoyance predictions.

Key Words: odor • beef cattle • diet • life cycle • feces • volatile organic compounds (VOCs) • solid phase microextraction (SPME)