As spring approaches, a common complaint heard on many dairies is that cows seem to be loose, intakes are down and the fat test is suffering, says Bill Mahanna, global nutritional sciences manager with Pioneer, a DuPont Company. This phenomenon, often referred to as “spring acidosis,” seems to occur most often in herds that feed more than 15 pounds of corn silage per head (on a dry-matter basis), combined with high-moisture corn in excess of 26 percent moisture, Mahanna says.
Research from the University of Nebraska shows that as kernel moisture and length of storage increase, the starch in the high-moisture corn becomes more digestible. European studies show this also occurs in the kernels of corn silage. This increase in ruminal starch digestibility may explain why producers see increased symptoms of acidosis in the spring.
Mahanna offers these tips to help minimize spring acidosis:
- Don’t vary high-moisture corn inclusion rates based on forage quality alone. Account for the increased energy available in long-stored, wet high-moisture corn during ration balancing.
- In spring, lower the inclusion rate of the wetter high-moisture corn in favor of more corn silage, or possibly replace some of the high-moisture corn with dry corn.
- Consider adding 1 to 2 pounds of straw to the ration to help develop the rumen mat and stimulate cud-chewing, which helps buffer the rumen. Adding buffers to the ration can help also.
- Monitor changes in ruminal starch digestibility. To do so, pull samples of both corn silage and high-moisture corn at 60 days ensiled. Freeze them. Pull samples again at 150 to 200 days ensiled. Send both sets of samples to a lab that offers a starch-digestibility analysis. Here are two labs that offer this test: Dairyland Laboratories, Arcadia, Wis., (608) 323-2123; and Cumberland Valley Analytical Services, Hagerstown, Md., (800) 282-7522.