Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
11/12/98
Contacts:
Marj Faust, Extension Dairy, (515) 294-2793
Treva Blumenshine, Extension Communication Systems, (515)
294-5672
Feeding Bt Corn Silage
AMES, Iowa -- Bt corn is not entirely new to the Iowa countryside, but this year, many producers may be working with Bt corn for the first time. What can producers expect through harvest and in the feedbunk for this new Integrated Pest Management (IPM) technology? Research studies have documented that Bt technology effectively can protect corn plants from damage by European Corn Borer (ECB) and several other corn pests, according to Marj Faust, Iowa State University Extension dairy specialist. "Pest protection will vary with different Bt hybrids. This pest protection can yield healthier corn plants, and higher moisture levels in Bt plants into the harvest season and in stored feeds compared to corresponding non-Bt hybrids. Data from Iowa State University studies and other trials indicate that producers overall may see lower mold and mycotoxin levels for Bt hybrids, too," said Faust.
Producers may ask whether they can expect different management or feeding related characteristics for Bt corn silage. Because of the "stay-green" ability for Bt corn, silage harvested from Bt corn may have higher moisture content than non-Bt silage. It is important to do periodic analyses of new-crop silages, according to Faust. Also, it is important to follow up with feed analyses whenever feeding different batches of silage. For producers who will be feeding corn silage from both Bt and non-Bt hybrids, routine (weekly) dry matter checks can help to fine tune feeding management. Frequent dry matter checks are recommended by dairy nutritionists regardless of the hybrids that were planted. These frequent checks are key to ensuring that rations meet demands day-in and day-out for high producing dairy cows. "Your local ISU Extension office can provide a list of forage testing laboratories and can help to set up routine dry matter analyses on the farm," said Faust.
Early studies conducted at ISU where high producing dairy cows were fed green chop from a non-Bt or from two different Bt hybrids found no differences in feed intake or milk production for these feeding groups. Group averages for cows fed these diets exceeded 84 pounds of milk daily during the two-week trial period. In addition, no differences were found between groups for milk composition and udder health measures, according to Faust.
Results from the ISU study using green chop corn indicate that when diets are formulated using frequent dry matter assessment, essentially no differences in performance or udder health are expected for cows fed silages from Bt or non-Bt corn. Studies are currently underway at ISU to evaluate silages made from 1998 crop Bt and non-Bt corn, according to Faust.
ml: isufarm
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