How is SoyPass® manufactured?
Click here to learn more.

A Three-Step In Vitro Procedure for Estimating Intestinal Digestion of Protein in Ruminants

[ three-step method, digestibility, blood, feather, meat & bone meal ]

A three-step in vitro procedure was developed to estimate intestinal digestion of undegradable intake proteins (UIP) in ruminants. Dacron bags containing feed samples were suspended in the rumen for 16 hours. Residues were then treated in vitro with acid, followed by incubation with pepsin-pancreatin enzymes.

Protein supplement

Digestible CP, %
of UIP*

Soybean meal




Corn gluten meal


Blood meal


Hydrolysed feather meal


Feather meal


Meat and bone meal

*Estimated by in vitro pepsin-pancreatin incubation

**Lignosulfonate-treated SBM

Digestibility of SoyPass and other vegetable proteins was high, with good correlation to expected values. Digestible UIP results for meat and bone meal and hydrolyzed feather meal were low and values for different samples of blood meal were highly variable.

Sergio Calsimiglia and M. D. Stern, (1995), J Anim Sci 73:1459-1465