Silica Concentrations in Grazed and Ungrazed Forage Species1
- B. C. Morton and
- M. W. Jutras2
The presence of silica (SiO2) has been reported as significantly affecting the nutritional value of forages. This study was conducted to determine the SiO2 concentration in forage samples collected monthly from 2-ha paddocks of ungrazed tall fescue (Festuca arundinacea Schreb.) and ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) as they matured, and to determine the monthly SiO2 concentrations of vegetative tall fescue, tall fescue-‘Ladino’ clover (Trifolium repens L.), orchardgrass (Dactylis glomerata L.), orchardgrass-Ladino clover, Coastal bermudagrass, and stockpiled tall fescue which were incorporated into four grazing systems. Samples representative of forage grazed by yearling beef heifers were collected monthly from caged areas to determine the SiO2 levels.
The SiO2 concentrations ranged from 0.30 to 2.65% in dry matter and exhibited variations between species and from month to month within a given species. Silica accumulated rapidly in the forage tissue early in the growing season and thereafter concentrations remained relatively constant. Actively growing forages maintained in a vegetative state by grazing did not exhibit appreciable monthly differences in SiO2 concentration. Increases in SiO2 concentration were noted during winter dormancy. These results indicate the need for further study of the hypothesis that SiO2 can be used to reveal the nutritive value of a forage, particularly the nutritive value of grazed forages.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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