Malate, Citrate, and Amino Acids in Tall Fescue Cultivars: Relationship to Animal Preference

Abstract

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 C1 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 acids 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 acid column. Amino acids 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−1 dry matter [DM], most preferred) than in Mozark (54 g kg−1 DM, least preferred). Citrate concentrations (13 g kg−1 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 acid 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 acid concentrations among cultivars.

Grazing Behavior and Diet Preference of Beef Steers Grazing Adjacent Monocultures of Tall Fescue and Alfalfa: I. Spatial Allocation

“…Simple sugars, starch, fructans, soluble fiber, and organic acids comprise NFC, while TNC does not include organic acids or soluble fibers such as pectins (Hall, 2007). Mayland et al (2000a) reported that organic acid concentration was not related to diet preference of cattle among eight tall fescue cultivars.…”

Alleviation of Drought Stress and Metabolic Changes in Timothy (Phleum pratense L.) Colonized with Bacillus subtilis B26

“…These changes will likely have a major negative impact on timothy regrowth potential ( Jing et al, 2014 ) and thus, on the supply of quality timothy forage to meet the cattle industry dietary needs ( Piva et al, 2013 ). Grazing animals depend on a variety of chemical cues when selecting which plants they will eat, with soluble energy (i.e., free amino acids and organic acids and water-soluble carbohydrates) being the primary factor for selection ( Maryland et al, 2000 ; Tamoura et al, 2009 ).…”

Grazing Behavior and Diet Preference of Beef Steers Grazing Adjacent Monocultures of Tall Fescue and Alfalfa: II. The Role of Novelty

“…Nonfiber carbohydrates (NFC) were calculated in this study (TNC + organic acids and soluble fiber) and were greater in alfalfa at both times of day, so organic acids and/or soluble fiber may be influencing the greater preference for alfalfa. However, Mayland et al (2000a) reported that organic acid concentration was not related to diet preference of cattle among eight tall fescue cultivars.…”