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Feeding Year Old Hay November 25, 2021, contributed by Yaremcio Ag Consulting, Ltd.

When hay is exposed to the weather, damage occurs. Ninety days after cutting, the vitamin precursors loose ‘strength’ and animals will require supplementation. Over wintered bale weights can be 8 to 12% less than when they were baled. Digestibility of the outer 5 inches of the bale is reduced by 20%. Free choice intake and digestibility of the hay can both be reduced by 10%. If the hay is kept over for a second year, additional weight loss occurs, and digestibility is reduced even further. In some situations, this older hay could be no better than feeding straw.

Microbial populations increase causing the hay to discolor and possibly mold formation. These organisms consume soluble proteins and carbohydrates which reduces forage quality. The presence of red, blue, green, or pink molds may have formed mycotoxins.

Bales stored under a shed, covered with a tarp, or wrapped in plastic; do not deteriorate over the winter as much as hay stored unprotected outdoors. If you were to feed test in the spring and compare it to the results from the previous fall, the protein, fiber (energy) and mineral content of the hay stored under cover would be very similar. This is not the case for hay that is stored outdoors, uncovered, and on the ground.

More weather damage occurs to legume hay compared to grass hay. Applying twine at 4 inch spacing reduces moisture entry and damage to the bale compared to bales with twine at 8 inch spacing. A denser or tighter bale sheds more water and has less weather damage than a looser bale. Net wrapped bales shed rain better and have less damage than bales tied with twine. Bales wrapped with solid plastic have the least amount of damage when stored outdoors.

If you are buying year old hay, how do you come up with a fair price?

  1. Weigh the bales. Don’t use average weights from last fall.

  2. Take a representative sample and test the feed. Does the quality meet your needs?

  3. Price should reflect the 10% reduction in digestibility for hay that was stored outdoors. If the cows cannot digest the hay efficiently, more nutrients end up in the manure.

  4. Compare the price of year-old hay to greenfeed or straw. Pay according to quality, not forage type.

Barry Yaremcio

Ruminant Nutritionist


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