Dry matter densities of corn silage vary widely within bunkers and piles, reducing the opportunity to feed consistent, high-quality dairy forage, according to a Penn State study.

In 2004, researchers Paul Craig and Greg Roth sampled 80 bunkers and piles at 12 points and found average densities ranging from 8.3 lbs dry matter/square foot to 16.8. The lowest densities were found on the highest levels and edges of piles.

A second study in 2006 examined the effects of time and location on forage quality and aerobic instability during feed-out from a 7,000-ton silage pile using a multi-pass feed-out system. Density and forage quality varied significantly during that time and at different levels within the pile.

The causes of variation? Different hybrids and harvest moistures, localized growing conditions, harvesting factors and packing. The researchers suggest that feed managers work to reduce variability and take frequent forage analyses.

The 2006 study also showed high forage quality can be maintained using a multi-pass feed-out program.