Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: June 3, 1996
Publication Date: N/A
Technical Abstract: Tarbush (Flourensia cernua DC) is a rapidly increasing Chihuahuan Desert shrub. Use of livestock to control tarbush is being examined. Whole plants (n=120) were harvested to assess nutrient composition during 3 years across 4 growth stages: early (EG), midpoint (MG), late (LG)and senescent (SG) growth. Plants were air-dried, then leaves were removed and freeze-dried. Nitrogen concentration was greatest for EG, lowest for SG and no different between MG and LG (P<.05; 3.95, 2.82, 2.77 and 2.62% of DM for EG, MG, LG and SG respectively). Soluble N content was greater and ADIN content was lower for EG (P<.05) than other stages. Insoluble N declined with advancing maturity (P<.05). As a fraction of total N, insoluble N decreased and soluble N increased with maturity (P<.05). IVDMD was greater for EG than the other stages (P<.05; 66.8, 61.0, 60.5 and 60.4% of DM for EG, MG, LG and SG respectively). Calcium concentration increased and P content decreased with maturity (P<.05). Concentrations of NDF and ADF were lowest for EG (P<.05), but did not differ among later growth stages. ADL content was least for EG and less for MG than LG or SG (P<.05). Condensed tannin content tended (P<.10) to increase with advancing season. Total phenolics concentration was least for EG (P<.05)and not different among the other growth stages (6.6, 8.1, 7.9 and 7.6% of DM for EG, MG, LG and SG, respectively). Nutrients and antiquality variables exhibited patterns normally associated with advancing phenology. Across seasons and years, tarbush was of reasonably high quality (3.0% N, 62.2% IVDMD, 20.8% NDF, 17.0% ADF, 1.51% Ca and 0.15% P, DM basis) and low in antiquality factors (0.1% ADIN, 6.6% ADL and .34% condensed tannins, DM basis), with the exception of total phenolics (7.6% of DM) and ether extract (13.6% of DM).