Nonstructural carbohydrates: Challenges and progress in forage testing

Shewmaker, Glenn and Mayland, Hank (2002) Nonstructural carbohydrates: Challenges and progress in forage testing. pp. 129-137. In: Proc. 37th Annual PNW Animal Nutrition Conf. Canada-BC-Vancouver, 2002/10/08-10.

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Abstract

Forage testing has evolved by adapting new technology but acceptance of different tests
for forage quality is slow and some tests are impractical. Reliance on technology has replaced
intuition and experienced knowledge in some cases. For example, alfalfa grown at high
elevations was preferred as dairy hay in the 1960's and 1970's. The use of forage testing in the
1980's and 1990's appears to favor alfalfa hay grown at lower elevations. Moreover, the forage
tests of acid detergent fiber (ADF) and neutral detergent fiber (NDF) do not consistently
predict animal intake or performance across cuttings. For example, hot season cuttings usually
have finer stems, are greener in color, and conventional tests show similar values of ADF and
NDF to first (cool season) cuttings, yet animal intake is less for the hot-season cuttings. Using
current forage testing to compare high versus low elevation grown hay, or to compare hays
from different cuttings, is not dependable. There are some promising developments which
should improve our ability to predict animal performance. The testing for nonfibrous
carbohydrates (NFC) or total nonstructural carbohydrates (TNC) are additional tools you may
want to use. Nonfibrous carbohydrates are defined by the National Research Council (2001) as
NFC = 100 - (%NDF + % CP + %Fat + %Ash), where CP is crude protein. Total nonstructural
carbohydrates are determined by a fractionation of the sample and are calculated as the sum of
monosaccarhides, disaccharides, short chain polysaccharides, and starch. This paper reviews
the underlying principles of forage quality and the development of testing; environmental,
genetic, and harvest management effects on forage quality; and reviews diurnal cycling of total
nonstructural carbohydrates and related animal preference studies.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	1081
Subjects:	Irrigated crops > Grass forage > Chemistry Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:56
Last Modified:	09 Nov 2016 18:31
Item ID:	946
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/946