"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
89.9

SoyPass**
87.3

Corn gluten meal
87.6

Blood meal
80.1

Hydrolysed feather meal
69.5

Feather meal
85.4

Meat and bone meal
54.0
*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