New research challenges the value of cutting corn silage at a higher-than-normal height to improve feeding performance. According to a University of Delaware study recently published in the Journal of Dairy Science, digestibility and cow performance were superior with brown mid-rib (BMR) corn silage cut at a normal height. The study compared the effects of silage cutting height on the nutritive value of a conventional corn silage hybrid compared with BMR corn silage fed to lactating cows.

The theory behind harvesting silage at a high cutting height is to leave the less digestible, high-lignin portion of the stalk in the field. In this study, harvesting a conventional corn hybrid at a high harvest height increased the concentration of some nutrients in the harvested plant (e.g., crude protein (CP), starch and energy), but did not affect neutral detergent fiber (NDF) digestion.

“The objective of this study was to evaluate the yield and feeding value of a dual-purpose corn silage hybrid harvested at a normal and high-cut length with BMR corn silage harvested at a normal cut length,” says Dr. Limin Kung Jr., professor, University of Delaware.

Digestibility was considerably greater for BMR corn silage compared with the normal- and high-cut conventional silage. That’s due to BMR’s lower lignin content. Higher digestibility translated into higher milk production for cows fed the BMR corn silage as part of a total mixed ration (TMR). Twenty-seven lactating cows were fed a TMR composed of the respective silages with alfalfa haylage, alfalfa hay and concentrate to balance the ration. Milk production was greater for cows fed the BMR hybrid compared with those fed the normal-cut or high-cut hybrids.

High-cut silage had the lowest estimated milk yield per acre of silages when using calculations from MILK2006. Because of this finding, cows fed BMR corn silage were more efficient at converting dry matter to fat-corrected milk (FCM) compared with cows fed high-cut corn silage. Dry matter intake was not affected by the type of corn silage in the TMR.

The hybrids used in this study were a MYCOGEN^® brand SILAGE-SPECIFIC^™ BMR hybrid (F2F797) and a MYCOGEN brand SILAGE-SPECIFIC non-BMR hybrid (7511FQ). “The BMR hybrid was harvested at a normal cut height, leaving 3.9 to 5.9 inches of stalk in the field,” Dr. Kung says. “The non-BMR hybrid was cut at the same height, and also at a greater height, leaving 17.7 to 19.7 inches of stalk.”

Feed efficiency for cows fed the BMR silage was greater than for those fed the high-cut conventional hybrid, but was not different from cows fed the normal-cut silage. Cows fed the BMR silage had milk with greater concentrations of lactose but lower milk urea nitrogen than cows on other treatments. Harvesting a SILAGE-SPECIFIC non-BMR corn hybrid at a high harvest height improved its nutritive content, but the improvement in feeding value was not as high as the BMR corn silage.

“Cutting high increased the concentrations of DM, CP, net energy for lactation and starch, but decreased the concentrations of acid detergent fiber (ADF), NDF and acid detergent lignin for 7511FQ,” Dr. Kung says. “As expected, the BMR corn silage was 30 percent lower in lignin concentration than 7511FQ.”

Mycogen Seeds is a retail seed company of Dow AgroSciences LLC and a developer and marketer of leading grain corn hybrids, the market leader in SILAGE-SPECIFIC corn hybrids and sunflower hybrids, as well as an industry leader in canola, alfalfa, soybeans and sorghum. For more information about MYCOGEN brand products, visit www.mycogen.com.

Dow AgroSciences LLC, based inIndianapolis, Indiana, USA, is a top-tier agricultural company that combines the power of science and technology with the “Human Element” to constantly improve what is essential to human progress. Dow AgroSciences provides innovative technologies for crop protection, pest and vegetation management, seeds, traits, and agricultural biotechnology to serve the world’s growing population. Global sales for Dow AgroSciences, a wholly owned subsidiary of The Dow Chemical Company, are $3.8 billion. Learn more at www.dowagro.com.