[Digestibility of ungraded crude protein from the rumen and of treated protein feeds in the postruminal part of the digestive tracts of ruminants].

The effective degradability and intestinal digestibility of CP of untreated and with formaldehyde (F) treated sunflower press--cakes (SF), lucerne meal (LM) and field beans (FB) were measured on polycannulated bulls by "in sacco" and "mobile bag" methods. The feeds were treated by F solution in doses from 0.2; 0.4... to 2.0 g F per 100 g CP. The effective CP degradability after treatment was decreased significantly (for SF from 78 to 33%, LM from 73 to 62%, FB from 70 to 47% with max. dose of F). The effect of F was various on individual feeds. The intestinal digestibility of treated feeds, without previous incubation in the rumen, passed from abomasum to feces has been influenced with doses of F non significantly. The digestibility of FB treated with max. dose of F was lower about 20% in the part duodenum feces than in abdomasum feces. The digestibility in the part caecum--feces for all tested feeds has been decreasing with doses of F, similar as in the rumen. The intestinal digestibility of in rumen undegraded crude protein residues of SF has been influenced by the treatment positively. It increased from 43 to 82%. The effect of F on LM was very low. The digestibility has been changed from 75 to 80%.