Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2006
Publication Date: July 10, 2006
Citation: Grabber, J.H., Mertens, D.R. 2006. Direct verses sequential analysis of acid-detergent insoluble nitrogen in forage legume hays [abstract]. In: Proceedings of the ADSA and ASAS Annual Meeting, July 9-13, 2006, Minneapolis, Minnesota. 2006 CD ROM. Technical Abstract: Acid-detergent insoluble nitrogen (ADIN) is thought to represent nitrogen that is not degraded during ruminal and post-ruminal digestion of forages by cattle. Forage ADIN can be determined following direct acid detergent extraction or following sequential extraction with neutral and acid detergents. In this study, we evaluated how direct verses sequential detergent extraction influenced the ADIN content of legume hays differing in polyphenol composition and degree of conditioning at harvest. In 2002 and 2003, first and second cuttings of polyphenol-free alfalfa, low to high tannin birdsfoot trefoil, and red clover with o-diphenols and polyphenol oxidase were conditioned by rolls or by maceration and then dried as hay. ADIN, as a proportion of total N, was determined by combustion after direct or sequential detergent extraction by the ANKOM filter bag system, without the addition of sulfite or amylase to neutral detergent solution. The forage X conditioning method X ADIN method interaction was highly significant (P < 0.0001, SEM 3.7 g/kg). In hays conditioned with rolls, ADIN concentrations by direct and sequential methods averaged 41 and 34 g/kg for alfalfa, 55 and 32 g/kg for low tannin trefoil, 50 and 38 g/kg for moderate tannin trefoil, 57 and 41 g/kg for high tannin trefoil, and 48 and 33 g/kg for red clover. In hays conditioned by maceration, ADIN concentrations by direct and sequential methods averaged 41 and 34 g/kg for alfalfa, 41 and 36 g/kg for low tannin trefoil, 33 and 40 g/kg for moderate tannin trefoil, 40 and 55 g/kg for high tannin trefoil, and 52 and 40 g/kg for red clover. Thus, analysis method, forage type, and severity of conditioning differentially influenced ADIN concentrations.