Alkali-Treated Orchardgrass and Alfalfa: Composition and In Situ Digestion of Dry Matter and Cell Wall Components

¹ Department of Dairy and Animal Science, The Pennsylvania State University, University Park 16802, USDA, Agricultural Research Service, US Dairy Forage Research Center (Pennsylvania Cluster), US Regional Pasture Research Laboratory, University Park 16802

The effect of varying levels of alkali treatment on composition and disappearance of DM and cell wall components of alfalfa and orchardgrass was measured. Three field replicates of first-cutting alfalfa (bud and midbloom) and orchardgrass (prehead and head) were treated at harvest with 0 (no solution applied or 100% water treatment), 2, 4, 6, or 8 g NaOH/100 g forage DM. Forages were hand cut, hand sprayed, and sun cured as hay. Alkali treatment decreased the NDF and ADF content of both maturities of orchardgrass; conversely, alkali treatment increased NDF concentration in both maturities of alfalfa. Regardless of maturity, CP content of alfalfa decreased as level of NaOH increased. After 72 h of in situ digestion, NaOH increased potentially digestible DM in both maturities of orchardgrass. Disappearance of NDF in mature orchardgrass increased as NaOH increased. Alkali treatment increased the extent of ferulic acid disappearance in immature orchardgrass and increased the extent of p-coumaric acid disappearance in mature orchardgrass. Sodium hydroxide treatment linearly increased the potentially digestible DM and NDF fractions in both maturities of alfalfa. Alkali treatment decreased the rate of DM digestion in alfalfa, regardless of maturity. Alkali treatment altered chemical composition and increased cell wall utilization of both orchardgrass and alfalfa.

Key Words: alkali • orchardgrass • alfalfa

Submitted on October 20, 1989
Accepted on February 26, 1990