It was proposed that the digestibility of organic matter (OMD) can be estimated from the relationship between total fecal nitrogen (TFN, as a % of organic matter intake (OMI) and fecal nitrogen concentration (FNc) through the equation: OMD = 1 - TFN/FNc. Two assumptions are critical to this equation, total fecal nitrogen (as a % of OMI) is a constant and does not change within a range of diet crude protein and fecal nitrogen concentration is proportional to digestibility of organic matter. The objective of this study was to test if total fecal nitrogen (as a % if OMI) remains constant over 3 feeding levels, and if fecal nitrogen concentration decreases with decreasing organic matter digestibility of maturing forages. Total fecal nitrogen did not change (P = 0.94) with feeding level, but increased (P < 0.05) with evaluation period. The fecal nitrogen concentration correlated (r = 0.60, P < 0.001) to digestibility of organic matter. The results show that digestibility of organic matter cannot be estimated from total fecal nitrogen, unless time of year is considered. The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020
Scholarly peer-reviewed articles published by the Society for Range Management. Access articles on a rolling-window basis from vol. 1, 1948 up to 5 years from the current year. Formerly Journal of Range Management (JRM). More recent content is available by subscription from SRM.