aNDF, NDFd, iNDF, ADL and kd: What have we learned?
aNDF, NDFd, iNDF, ADL and kd: What have we learned?
aNDF, NDFd, iNDF, ADL and kd: What have we learned?
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Figure 7: Relationship bet<strong>we</strong>en 96hr NDFD <strong>and</strong> ether linked FA in NDF residues<br />
<strong>NDFd</strong> Procedure<br />
The in-vitro procedure used to obtain a <strong>NDFd</strong> value is used to calculate a rate of<br />
NDF digestion. We therefore want to control of all the factors that would bias the<br />
calculation. Besides the estimation of the <strong>iNDF</strong>, other important factors are the lag <strong>and</strong><br />
the pool size. It is therefore a must minimizing the lag <strong>and</strong> avoiding loss of sample<br />
during the procedure:<br />
- Fast h<strong>and</strong>ling of rumen fluid from the barn to the lab<br />
- Care in keeping the rumen fluid temperature at 39° C <strong>and</strong> anaerobic<br />
- Filtration of the fluid <strong>and</strong> not blending<br />
- Total time bet<strong>we</strong>en barn <strong>and</strong> inoculation of the samples should not be<br />
higher than 20-25 minutes.<br />
- Use of glass microfiber filter 934-AH or GF/C with porosity of 1.5 µ<br />
(<strong>What</strong>man)<br />
- Particular care of hot <strong>we</strong>ighing because of filters <strong>and</strong> moisture variation<br />
- Use of blanks for inoculums/filter loss/gain correction<br />
<strong>ADL</strong> Procedure<br />
Variation in the <strong>ADL</strong> procedure has been observed in many laboratories <strong>and</strong> is<br />
especially observed n lo<strong>we</strong>r lignin forages, like bmr corn silages, higher digestibility corn<br />
silages <strong>and</strong> immature grasses. Better care should be devoted to this types of forages<br />
during the procedure. Use of glass microfiber filter like 934-AH or GF/C is highly<br />
recommended along with more attention during the hot <strong>we</strong>ighing. The removal of<br />
asbestos as a filtering agent has most likely contributed to increased variation in <strong>ADL</strong><br />
recoveries. Also, use of blanks is recommended because of possible sulfuric acid<br />
degradation of filters. To decrease the chance of filter degradation, the sample can be<br />
put in a small beaker (50 to 100 ml) soaked in excess sulfuric acid, stirred appropriately<br />
<strong>and</strong> then filtered in crucibles with filters.