Ankom dietary fiber analyzer

The feed ingredient of CB was purchased from Wellhope Agri-tech Co. Ltd. (Beijing, China). Fiber composition of CB was analyzed, including cellulose, hemicellulose, lignin, insoluble DF (IDF), soluble DF (SDF), total DF (TDF), total non-starch polysaccharides (NSP), and eight constituent monosaccharides of NSP, namely rhamnose, fructose, ribose, arabinose, xylose, mannose, galactose, and glucose. The contents of IDF and TDF were measured according to AOAC method of 991.43 using Ankom Dietary Fiber Analyzer (Ankom Technology, United States). The contents of NSP and their monosaccharides were analyzed on the basis of alditol acetates by gas–liquid chromatography (Agilent GC 6980, United States) as described by Liu et al. (2017) (link). The fiber composition of CB was shown in Supplementary Table 2.

Dry matter (DM, AOAC 930.15), ash (methods 942.15), crude protein (CP, methods 990.03) and ether extract (EE, method 920.39) contents were determined following the AOAC (2006) procedures. According to the methods of AOAC (2007), soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and total dietary fiber (TDF) were analyzed by using the Ankom Dietary Fiber Analyzer (Ankom Technology, Macedon, NY, USA). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were detected using the filter bags (Model F57; Ankom Technology) and fiber analyzer equipment (ANKOM200 Fiber Analyzer, Ankom Technology). The milk samples were separately analyzed for the concentrations of fat, protein, lactose, and DM using a Milko-Scan FT 120 (Foss Electric, Hillerford, Denmark).