Determination of Water-Insoluble Cell Walls in Feeds: Interlaboratory Study

Abstract

A collaborative study was conducted to test a new rapid procedure for determination of water-insoluble cell wall (WICW) content in feeds. In the method, starch is solubilized near boiling temperature with Termamyl, a heat-stable alpha-amylase, and proteins are solubilized at 40 °C with sodium dodecylsulfate and Pronase. Then, the organic matter of the residue is determined by incineration. Three hours were required to treat 12 different samples, including solubilization treatments, filtrations, and rinses. Eleven unknown products including 9 common feedstuffs of various origin and 2 mixed diets for poultry were analyzed by 7 analysts in France. Coefficients of variation ranged from 2.3 to 6.1%. The results were compared to those for water-insoluble dietary fiber (WIDF), total dietary fiber, and neutral detergent fiber. Agreement was best with the water-insoluble dietary fiber procedure. For most samples, the ratios of WIDF/WICW ranged from 0.981 to 0.842. The differences between WICW and WIDF values correspond to cell wall protein which is accounted for in WICW, but not in WIDF.

Evaluation of protein and starch digestibility and energy value of pelleted or unpelleted pea seeds from winter or spring cultivars in adult and young chickens

“…As an illustration of this, by use of the AMEn predicting equation based on gross energy, crude protein, and waterinsoluble cell walls (Carré and Brillouet, 1989), the AMEn values of diets for adult cockerels were predicted accurately, except for diets containing unpelleted peas (WPqp and SPop). For these two diets, the differences (0.88 MJ/ kg) between predicted and measured AMEn values were outside the range of the residual confidence limit previously found (0.44 MJ/kg; Carré and Brillouet, 1989), whereas the differences for basal (0.08 MJ/kg) and pelleted pea diets (0.36 MJ/kg) were within the range of the residual confidence limit. The latter calculation also shows that the use of peas, if pelleted, leads to normal AMEn values for diets given to the chicken.…”

“…from Rhizopus mold (Sigma A-7255,10 units/mg) was used instead of the 20 mg of amyloglucosidase from Aspergillus niger (Boehringer Mannheim, W. Germany) to treat the suspension for 6 h. A blank value was run without sample for starch determination. The contents of the water-insoluble cell wall were measured as described previously (Garré and Brillouet, 1989). The number of trypsin units inhibited (TUI) per milligram was estimated according to the method of Kakade et al (1974) modified by Valdebouze et al (1980).…”

Fibre digestion.

“…Xyloglucans are the major hemicelluloses of the primary cell wall in dicotyledonous plants (legumes, seeds), whereas mixed linked glucans (β[1→3,4]) and arabinoxylans are the predominant hemicelluloses in cereal seeds (the latter two include partly water-soluble and water-insoluble polymers, described above). (Carré and Brillouet, 1989). c Neutral detergent soluble fibre (Hall et al, 1997 Lignin is a non-carbohydrate constituent of the cell wall.…”