Grazing animals depend on little-understood chemical and physical
cues when selecting forage diets. This study determined malate, citrate,
and amino acid concentrations in endophyte-free tall fescue (Festuca
arundinacea Schreb.) and related those concentrations to cultivar,
harvest time, and grazing-animal preference. Barcel', 'Kenhy', 'Kentucky-31',
'Missouri-96', `Mozark', `Stargrazer, and the two accessions
Cl and HiMag were established in three replicates within each of
three pastures. Organic acids were determined on regrowth within
each plot during four seasons and two years; amino adds were determined
on regrowth of four cultivars across three replicates during
both spring and fall seasons in one year. Malate and citrate were
extracted with boiling water and quantified by high-performance liquid
chromatography (HPLC) with an organic add column. Amino
adds were hydrolyzed, separated by ion-exchange HPLC, and quantified
as their ninhydrin derivatives. Both malate and citrate concentrations
differed between years. During one year only, malate concentrations
were higher in Kenhy (68 g kg-' dry matter [DM], most
preferred) than in Mozark (54 g kg-, DM, least preferred). Citrate
concentrations (13 g kg-' DM) were not different among cultivars.
Eighteen amino acids (including tryptophan) accounted for 75% of
total N. Thus, tissue N data were used as covariates to amino add
data in the ANOVA. Kenhy contained higher concentrations of eight
amino acids than did other cultivars. These differences may reflect
presence of Lolium genes in Kenhy. Cattle (Bos taurus L.) grazing
preference (0 = not eaten; 10 = completely eaten) was not related
to malate, citrate, or amino add concentrations among cultivars