In the previous article, Value of Covering Silage, discussion focused on how uncovered silage quality is negatively impacted during the fermentation and storage periods.
Using a hypothetical situation as an example, a silage pit is a concrete bunker with straight walls. The pit holds 1,000 tons of silage. The dimensions are 50 feet wide, 110 feet long, and the silage is 12 feet deep. Silage density is 40 pounds per cubic foot (as fed). The silage is valued at $50 per ton.
Shrink:
With a covered pit, shrink can be 5 to 8%. This reduces the amount of silage available to feed by 50 to 80 tons. If an uncovered pit has a 12% shrink, the loss is 120 tons.
Top Spoilage:
For ease of calculation, the top of the silage pit is flat and not rounded. Visible spoilage after fermentation is complete is 4 inches. Using the conversion of 4 inches of packed material for every inch of spoiled material; the loss of good quality silage is 16 inches. Total cubic feet of fresh silage lost is 1.33 feet (depth) x 50 feet (length) x 100 feet (long) equals 6,650 cubic feet. Multiplying 6,650 cubic feet by the density of 40 pounds per cubic foot, the loss is 133 tons.
Value of Losses:
In the covered pit, with 8% shrink, there is 920 tons silage available to feed when no spoilage is present. The uncovered pit with 12% shrink and 4 inches of top spoilage, there is 827 tons of silage available to feed. A difference of 93 tons valued at $4,650.
If a cow is fed 60 pounds of silage per day, and there are 100 cows in the herd, the number of total feeding days available is reduced by 31 days.
Preventing additional shrink and spoilage losses by covering silage piles or pits with plastic has a big impact on the amount of available feed. The economic returns is worth the investment of time and plastic.
For additional information about covering silage pits and piles, contact Barry at 403-741-6032 or bjyaremcio@gmail.com.
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