Using 15N dilution method to correct for microbial contamination when assessing in situ protein degradability of fresh ryegrass

Author(s)
Tahmasbi, R
Nolan, John
Dobos, Robin
Publication Date
2016
Abstract
This experiment was done to investigate microbial contamination and in situ disappearance rates of dry matter (DM), N and 15N of fresh labeled ryegrass. Perennial ryegrass (Lolium perenne) were labeled with 15N during growth in a glasshouse, harvested at 4th leaves stage and were incubated up to 34 h in situ in the rumen of 3 individually housed sheep. The animals were fed 800 g/d chopped alfalfa and had free access to drinking water. Six bags were placed in the rumen of ach sheep simultaneously and removed after 0, 3, 7, 12, 21 and 33 h after incubation. The results were fitted to a model describing the degradation of DM and total N with time. It was found that residues from the washed zero time bags had lower e 15N enrichments (7.7% vs. 8.3% enriched) than the original fresh samples. Under-estimation of effective degradability (ED) of protein in fresh forages by about 4% would have potential consequences for predictions of ruminally fermentable and escape protein and thus for dietary protein feeding management. However, because the correction assumes contaminating microbial N is unlabeled, but microbes attached to labeled ryegrass would become labeled to some extent, the true error and effective degradability may still be underestimated. Studies with two markers would help us to better understand the errors associated with the in situ technique.
Citation
Iranian journal of applied animal science, 6(2), p. 309-315
ISSN
2251-631X
2251-628X
Link
Publisher
Danishgahi Azadi Islami Rasht Branch
Title
Using 15N dilution method to correct for microbial contamination when assessing in situ protein degradability of fresh ryegrass
Type of document
Journal Article
Entity Type
Publication

Files:

NameSizeformatDescriptionLink