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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #142165
Title: COMPARISON OF FEEDING CORN SILAGES FROM LEAFY OR CONVENTIONAL CORN HYBRIDS TO LACTATING DAIRY COWS

Author
item NENNICH, T - UNIV OF MINNESOTA
item LINN, J - UNIV OF MINNESOTA
item JOHNSON, D - UNIV OF MINNESOTA
item ENDRES, M - UNIV OF MINNESOTA
item Jung, Hans Joachim

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2003
Publication Date: 10/1/2003
Citation: Nennich, T.D., Linn, J.G., Johnson, D.G., Endres, M.I., Jung, H.G. 2003. Comparison of feeding corn silages from leafy or conventional corn hybrids to lactating dairy cows. Journal of Dairy Science. 86:2932-2939.

Interpretive Summary: Corn silage is one of the most important feedstuffs utilized in dairy and beef production. Nutritional quality of corn silage depends on its starch and fiber content, and the digestibility of these components. Every year farmers are faced with a range of new corn hybrids that claim to be of greater nutritional value. Corn breeders have produced these new hybrids by incorporating special genetic traits that may improve silage quality. Unfortunately, most of these special traits have only been evaluated using laboratory methods, not by actually feeding the new crop varieties to livestock. One of these new genetic traits is the "leafy" gene that gives corn plants more leaves (which are more digestible than stem material) and a form of starch that is thought to be more digestible. A study was conducted to evaluate the value of the leafy trait in corn silage compared to a conventional corn hybrid selected for grain production. Some improvement in fiber digestibility was found for one of the two leafy hybrids tested using a laboratory method, but no improvements in milk production or milk composition were observed for dairy cows fed the leafy corn silage hybrids compared to the conventional hybrid. Unfortunately, the three hybrids did not share the same basic genetic ancestry, which makes direct comparisons difficult. Additional testing of the leafy trait must be done with more corn lines to prove if the leafy gene does or does not confer an improvement in corn silage quality. These results will be of value to corn breeders developing new hybrids, researchers who evaluate corn silage hybrids, and farmers making decisions as to which corn hybrids to grow.

Technical Abstract: Three corn hybrids (Pioneer 36F30, Mycogen TMF2450, and Mycogen TMF2404) were compared for yield, plant components, nutrient composition, in vitro digestibility, apparent digestibility, and lactation performance by Holstein cows. The three corn silages were harvested at a target of 33 to 35% dry matter. Before harvest, six corn plants were randomly selected for plant fractionation. Grain to stover ratios were 0.92, 0.70, and 0.95 for the 36F30, TMF2450, and TMF2404 corn plants, respectively. Fifty-two multiparous Holstein cows were placed on a covariate diet for 21 d after parturition. Cows were then randomly assigned by calving date to one of three dietary treatments, containing approximately 40% (dry matter basis) corn silage, for 120 d of lactation. Milk yield, milk components, and dry matter intake did not differ among dietary treatments. In vitro dry matter and neutral detergent fiber digestibilities were numerically higher for TMF2404 than the other corn silage hybrids, and in situ dry matter digestibility was higher for TMF2404 (53.2%) than 36F30 (42.8%) with TMF2450 (47.7%) being intermediate. In situ starch digestibility was highest for TMF2450 (86.2%) followed by TMF2404 (82.4%) and 36F30 (78.1%). Apparent total-tract neutral detergent fiber digestibility as measured by acid insoluble ash was higher for TMF2450 than the other two hybrids, but starch digestibility was not different between the corn silage dietary treatments. Although differences in nutrient content and digestibility existed among corn silage hybrids, inclusion of these hybrids in lactating cow diets at 40% of the dietary dry matter did not have a significant impact on lactation performance of dairy cattle.