NUTRITIVE VALUE AND IN VITRO DIGESTIBILITY OF NON-CONE HOP (HUMULUS
LUPULUS L.) BIOMASS
L. K. Rutto1,*, V. W. Temu1, G. Ferreira2 and M. K. Kering1
1Agricultural
Research Station, Virginia State University, PO Box 9061, Petersburg, VA 23806,
USA
2Department of Dairy Science, Virginia
Tech, 2100 Litton Reaves Hall, Blacksburg, VA 24061, USA
*Corresponding Author Email: lrutto@vsu.edu
ABSTRACT
More than 50% of
hop (Humulus lupulus L.) biomass is discarded as waste. Potentially,
this by-product, comprising leaves, bines, and unrecovered cones (non-cone
biomass) can be processed into a high value forage. In this study we used
classical forage and hop analysis methods to determine the nutritive and
chemical properties of non-cone biomass from five (Cascade, Chinook, Newport,
Nugget and Zeus) hop cultivars. Cascade had significantly higher crude protein (p≤0.05), while ash, starch and sugar
content were not statistically different among cultivars. Acid and neutral detergent
fiber ranged between 187-295 g·kg-1 and 274-397 g·kg-1 of
DM, respectively, with Cascade recording significantly (p≤0.05)
higher fiber than other cultivars. In vitro, dry matter (604-685 g·kg-1)
and NDF (374-478 g·kg-1) digestibility were significantly
(p≤0.05) higher in Newport, while true dry matter disappearance
(709-793 g·kg-1) was significantly (p≤0.05) lower in Cascade.
Variations were also observed in plant metal content with Ca being
significantly (p≤0.05) lower in Cascade, K in Nugget, and S in
Zeus, while Mg was highest in Newport. Overall, crude protein and
non-structural carbohydrate content in hop biomass were comparable,
respectively, to alfalfa, and to forage grasses like brome and Kentucky
bluegrass, and acid and neutral detergent fiber levels were slightly lower than
in alfalfa and legume-grass hays. Digestibility also compared favorably to
other forages including legume-grass hays and alfalfa silage. Hop biomass can
be a good source of dietary calcium, magnesium, and trace elements, and
furthermore was found to contain low levels of lupulone, a compound in cone
biomass recommended as a natural alternative to synthetic antibiotics. Our
findings suggest non-cone hop biomass may be of significant value as a
supplement in livestock nutrition.
Key
words: Humulus lupulus; Non-cone biomass; Nutritive value; Mineral content; a and b acids.
https://doi.org/10.36899/JAPS.2020.4.0093
Published online April 25, 2020 |
