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