Effects of correcting in situ ruminal microbial colonization of feed particles on the relationship between ruminally undegraded and intestinally digested crude protein in concentrate feeds.

Background: In situ estimates of ruminally undegraded protein (RUP) and intestinally digested protein (IDP) of ten concentrates, uncorrected or corrected for the ruminal microbial colonization, were used to examine the effects of this correction on the relationship between IDP and RUP values. Both variables were established for three rumen and duodenum cannulated wethers using N labeling-techniques and considering measured rates of ruminal particle comminution (k ) and outflow (k ).

Results: A covariance analysis showed that the close relationship found between both variables (IDP = -0.

Protein value of cereals and cereal by-products for ruminants: a comparison between crude protein and protein-based estimates.

In situ estimates of ruminal undegraded fraction (RU) and effective intestinal digestibility (EID, corrected for microbial colonisation) of dry matter (DM), crude protein (CP) and total analysed amino acids (TAA) of rye, wheat and corn grains, wheat bran, wheat and barley distillers' dried grains with solubles (DDGS) and corn gluten feed were measured on three rumen and duodenum cannulated wethers using (15)N labelling techniques and considering ruminal rates of particle comminution (kc) and outflow. Results indicate that not considering kc and microbial colonisation led to considerable overestimations of RU which increased with feed ruminal degradation. Microbial colonisation may be also associated with overestimations of EID, whose estimates for DM, CP and TAA were predicted from parameters related with the ruminal escape of intestinally indigestible materials.

Amino acid availability in ruminants of cereals and cereal co-products.

Background: Microbial corrected in situ estimates of the ruminal undegraded fraction (RU) and intestinal effective digestibility (IED) of amino acids (AA), except tryptophan, of rye, wheat and corn grains, wheat bran, wheat and barley distilled dried grains and corn gluten feed were measured on three rumen- and duodenum-cannulated wethers using (15)N-labelling techniques and considering ruminal rates of particle comminution and outflow.

Results: The lack of microbial correction led to overestimations of the intestinal digested fraction that rose with the increase in ruminal degradability. Thus these overestimations varied widely among feeds (from 4.

Effects of the comminution rate and microbial contamination of particles in the rumen on in situ estimates of protein and amino acid digestion of expeller palm kernel and rapeseed meal.

Background: Microbial corrected effective in situ estimates of ruminal undegraded fraction (RU) and intestinal effective digestibility (IED) of dry matter (DM), crude protein (CP) and amino acids (AA) of expeller palm kernel (EPK) and rapeseed meal (RSM) were measured on three rumen- and duodenum-cannulated wethers using ¹⁵N labelling techniques and considering ruminal rates of comminution (k(c)) and outflow (k(p)) of particles.

Results: The lack of k(c) and microbial correction overestimated the RU of DM by 4.91% (EPK) and 9.