Warm-Season Legumes for Nutritive Values and Digestibility

Kun-Jun Han  |  6/4/2012 8:00:31 PM

Fig. 1. IVTD (in vitro true digestibility) of legume forages meaured at 12 hr incubation intervals.

Fig. 2. Fermentation gas (in vitro rumen incubation) production of legume forages.

Introduction
Four nonconventional warm-season forage legumes, rhizoma peanut (A. glabrata), trailing wild bean (S. helvula), lablab bean (L. purpureus) and  Korean lespedeza (K. stipulacea) were investigated for protein, fiber, digestibility (IVTD, in vitro true digestibility), and in vitro rumen fermentation. In vitro rumen fermentation is a relatively new method measuring fermentation gas production (mainly CO2 and CH4) from feed samples, and the method is advantageous over in vitro digestibility with measuring fermentation from soluble and non-soluble substrates.

Table 1. Protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) in alfalfa, rhizoma peanut, wild bean, lablab bean and Korean lespedeza.

Nutritive value,
g kg -1 DM

Alfalfa

Rhizoma peanut

Trailing wild bean

Lablab bean

Korean lespedeza

CP

173a†

  148cd

162bc

 171ab

135d

NDF

428b

448a

 436ab

347c

349c

ADF

369a

330b

335b

283c

296c

† numbers followed by the same letter within the same row were not significantly different at P < 0.05.


Summary
Warm-season legume forage is a valuable resource in the southern U.S., providing livestock with high protein and energy. Warm-season legume forage feed values, digestibility and in vitro gas production were compared with those of similar growth stage (mid-bloom) alfalfa hay. The 48-hour in vitro true digestibility (IVTD) of lablab bean and rhizoma peanut were equivalent to that of alfalfa (80%). The IVTD at 36 and 48 hours were not different in tested legumes except for Korean lespedeza. Gas production per 100 mg of Korean lespedeza produced the least gas (3.10 ml), and alfalfa and lablab produced the most gas (26.4 ml and 24.3 ml, respectively).

Some warm-season legumes’ rumen degradation is lower than alfalfa. Legume forages known for high tannin or bloat-free qualities (Korean lespedeza) demonstrated lower in vitro true digestibility and low gas production. Low gas production may indicate a low level of substrate supply to rumen bacteria and more rumen bypass protein for a host animal.

Rate This Article:

Have a question or comment about the information on this page?

Innovate . Educate . Improve Lives

The LSU AgCenter and the LSU College of Agriculture

Top