Factors affecting ANKOM™ fiber analysis of forage and browse varying in condensed tannin concentration

BACKGROUND: Browse species containing condensed tannins (CTs) are an important source of nutrition for grazing/browsing livestock and wildlife in many parts of the world, but information on fiber concentration and CT–fiber interactions for these plants is lacking. RESULTS: Ten forage or browse species with a range of CT concentrations were oven dried and freeze dried and then analyzed for ash‐corrected neutral detergent fiber (NDFom) and corrected acid detergent fiber (ADFom) using separate samples (ADFSEP) and sequential NDF‐ADF analysis (ADFSEQ) with the ANKOM^? fiber analysis system. The ADFSEP and ADFSEQ residues were then analyzed for nitrogen (N) concentration. Oven drying increased (P < 0.05) fiber concentrations with some species, but not with others. For high‐CT forage and browse species, ADFSEP concentrations were greater (P < 0.05) than NDFom values and approximately double the ADFSEQ values. Nitrogen concentration was greater (P < 0.05) in ADFSEP than ADFSEQ residues, likely due to precipitation with CTs. CONCLUSION: Sequential NDF‐ADF analysis gave more realistic values and appeared to remove most of the fiber residue contaminants in CT forage samples. Freeze drying samples with sequential NDF‐ADF analysis is recommended in the ANKOM^? fiber analysis system with CT‐containing forage and browse species. Copyright © 2010 Society of Chemical Industry