RI-ERP-FINALACTION-Recommendations
6343
UPDATING AND ASSESSING THE CNCPS FEED LIBRARY
Table 2. Equations used by the Cornell Net Carbohydrate and Protein System (CNCPS) to calculate carbohydrate and protein fractions
Equation no.
Fraction 1
Equation 2,3
Description
CHO j CC j CB3 j NFC j CB2 j CA1 j CA2 j CA3 j CA4 j CB1 j PA1 j 4 PA2 j PB1 j PB2 j
Carbohydrates Indigestible fiber Digestible fiber Nonfiber CHO
100 − CP j − EE j − Ash j
[1] [2] [3] [4] [5] [6] [7] [8] [9]
(aNDFom j × (Lignin j × aNDFom j ) × 2.4)/100 or, aNDFom j × uNDFom j
aNDFom j − CC j CHO j − aNDFom j
Soluble fiber
NFC j − CA1 j − CA2 j − CA3 j − CA4 j − CB1 j Acetic j + Propionic j + (Butyric + Isobutyric) j
Volatile fatty acids
Lactic acid
Lactic j
Other organic acids
Organic acids j
WSC Starch
WSC j Starch j
[10] [11] [12] [13] [14] [15] [16]
Ammonia
Ammonia j × (SP j /100) × (CP j /100)
Soluble true protein Insoluble true protein Fiber-bound protein Indigestible protein Sum of composition
SP j × CP j /100 − PA1 j
CP j − (PA1 j − PA2 j − PB2 j − PC j ) (NDICP j − ADICP j ) × CP j / 100
PC j
ADICP j × CP j / 100
SUM j
100 = CP j + EE j + ash j + NDF j + acetic j + propionic j + isobutyric j + lactic j + + other organic acids j + WSC j + starch j + soluble fiber j
1 Subscript j means the j th feed in the library. 2 EE = ether extract; WSC = water-soluble carbohydrates; SP = soluble protein; ADICP = acid detergent-insoluble CP; NDICP = neutral detergent-insoluble CP; aNDFom = NDF assay with amylase, sodium sulfite and ash correction; uNDFom = undigested NDFom after a 240-h in vitro fermentation and ash correction. 3 Chemical components are expressed as percent DM except: SP = % CP; ADICP = % CP; NDICP = % CP; ammonia = % SP; lignin = % NDF; uNDFom = unavailable aNDFom, % NDF. 4 Previous versions of the CNCPS feed library use NPN for the PA1 fraction. This has been replaced with ammonia.
ash contamination could also influence estimates of kd. Commercial laboratories have addressed this issue through determination of NDF digestibility on an OM basis. Using NDF assay with amylase, sodium sulfite and ash correction ( aNDFom ) in future updates of the library is recommended to remove variance associated
with ash contamination. Evaluation against laboratory data compared each individual feed in the feed library to the mean and SD of the corresponding feed in the databases available from the commercial laboratories. Each component within each feed was required to fall within 1 SD of the mean value from the laboratory data
AOAC Researc Institute ERP Use Only
Figure 1. Frequency distributions for corn silage ash (A) and NDF (B) generated using commercial laboratory data sets (n = 21,000; Cumberland Valley Analytical Services Inc., Maugansville, MD, and Dairy One Cooperative Inc., Ithaca, NY).
Journal of Dairy Science Vol. 98 No. 9, 2015
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