Feed

Drying Recommendations

After collection, plant material should be washed to remove any residual soil or dust.

For phenols: Dry samples at 50 - 52°C for 24 hours using a forced air oven. Avoid drying higher than 55°C as it could affect phenolic quantification. Best practice is to immediately freeze samples with liquid nitrogen and then freeze-dry the samples without thawing. Store the freeze-dried material in a dark, dry location (e.g., a desiccator).

Fresh samples or those suspected to be moist: Place samples into paper bags (with adequate room for air movement within the bag) and dry in a forced air oven at 55-60°C. In general, adequate drying time is approximately 12 hours or until the material snaps or breaks easily. All samples, except freeze drying material, should be turned every 24 hours. Upon request, the lab is able to dry the samples at no additional cost.

Drying Exceptions:

  • Range samples take 24 hours or more to dry
  • Power plant ash samples take three days to dry
  • Solid pieces of wood take 24 hours to dry
  • Any material larger than gallon size will take one or more days to dry
  • Fruits and vegetables should be freeze dried and pureed (weigh the samples before and after the freeze-drying process)

Note: These time frames are based on use of a large, forced-air oven. Times need to be adjusted accordingly for other types/sizes of ovens.

Grinding Recommendations

Most plant and feed samples should be ground to pass through a 40-mesh screen. HOWEVER, for methods 635, 640, and 650, the grind must be larger and pass through an 18-mesh screen. Large wood samples must be splintered into smaller pieces before grinding. The maximum unground sample size is one (1) large #56 grocerybag.  Upon request, the lab is able to grind the samples for a per sample charge.

Grinding Exceptions:

  • Grape blades – use a 20-mesh screen due to tricomb separation from leaf
  • Sugar beet petioles – use a 20-mesh screen due to high sugar content
  • Corn stalks – use a 10-mesh screen due to high sugar content
  • Freeze dried samples – do not need to be ground as they are easily crushed manually

Sample Storage and Amount Required: