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Research Project - The Evaluation of Corn Silage Samples Impacted by Hurricane Irene

Dan Hudson, Extension Agronomist, University of Vermont Extension, St. Johnsbury

If you are a farmer with flood-damaged corn, or an industry partner with related interests, and would like to have flood-damaged corn silage tested, you may be interested in this project.  As a collaborator in the project, the $275/sample cost of the extensive testing will be covered.  However, you need to download the testing protocol and following the directions carefully.  PLEASE NOTE the part of the attached protocol that states, "This sheet must be completed and sent to Jonathan Lim at the University of Delaware to obtain an ID number BEFORE a sample is sent to Cumberland Valley Analytical. Email to JONLIM@udel.edu 302 831 2269"

Project Objectives
To date, we have not been able to identify published research on documenting and evaluating the effect of flood damaged corn on silage fermentation and its resulting nutritive value for ruminants. Thus, the objectives of this study will be to collect and analyze samples of flood-impacted corn silage in the Northeastern region of the US to

a) determine the degree of soil and heavy metal contamination
b) determine if the compromised crops ensiled normally by analyzing for normal fermentation profiles and volatile organic compounds
c) determine the occurrence and quantify concentrations of mycotoxins
d) qualitatively assess the degree of contamination from major microbial pathogens
e) to assess the nutritive value of impacted silage.

It is anticipated that data obtained from this study will serve as valuable benchmarks that can be used for harvest and feeding recommendations in the future should such a disaster happen again. Data from this trial will be made public but identification of specific farms will be kept confidential. Partners from industry who contribute funding to the project will be recognized in all presentations and publications of the data.

For those who are interested, an abridged version of the project introduction and materials/methods can be found below.  If you are an industry partner and would like to support this effort, please contact Limin Kung (lksilage@udel.edu).  From industry, we currently have project support from BASF, Mycogen, Prince, Lallemand, Church and Dwight (THANK YOU!).

If you have other questions about this study, please feel free to contact any of the project contacts for this study:
Dr. Limin Kung, Jr., University of Delaware – lksilage@udel.edu
Dr. Dan Hudson, University of Vermont - djhudson@uvm.edu
Dr. Larry Chase, Cornell University - lec7@cornell.edu

Dr. Julie Smith, University of Vermont - julie.m.smith@uvm.edu

Background Information
Hurricane Irene caused severe damage to crops in the Northeastern part of the United States. This event occurred approximately one month prior to harvest for corn silage. High winds and rain resulted in various degrees of lodging to corn plants. In some fields, lodging was so severe that harvesting was impossible.  Flooding from over flowing rivers also resulted in plants being submerged under water for various lengths of time. Plants under stress from flooding usually respond by reduced photosynthesis and are thus more prone to root, ear, and stalk rot. In many instances, the flooding that occurred due to Hurricane Irene was above the ears of corn. When floodwaters receded, large quantities of silt remained on the ears, leaves, and stalks of the plants. Corn plants were so extremely silt laden in some fields that some farmers did not harvest portions of their flood-damaged acres due to the impact on harvesting equipment and concern about the impact of the harvested product on animal health.   A small amount of forage that was harvested from one such farm was tested and contained 28% ash (normal content should be about 4.2%) and 7,242 ppm Fe (normal levels of Fe are about 200 ppm in corn silage). The same forage also contained 4,368 ppm Al. Levels of Mg, Mn, Cu and Zn were higher than normal. The high Fe content was likely a combination of the soil itself as well as a result of soil wearing on the chopping blades of the harvester. Although a high percentage of the Fe in this sample was probably in the ferric form (Fe3+) form and insoluble, there would be potential for reduction to the ferrous form (Fe2+) by acidic conditions in silage and the abomasum of a cow leading to excessive amounts of available Fe. High levels of this Fe have been documented to interfere with normal Zn and Cu status in ruminants. High Fe has also been reported to depress DM digestion and reduce VFA production in batch cultures of ruminal fluid. High Fe in feed (1992 ppm) was hypothesized to cause toxicity in cattle. Excess concentrations of Fe and Al have decreased intake and gain in lambs. High levels of Al fed to calves has been reported to decrease intake and BW gains by 17 and 47%, respectively. Flood-impacted corn plants could also alter ensuing silage fermentations because of the increased content of ash and floodwaters contained mixtures of over flowing rivers with farm and municipal wastes. High ash could add to the buffering capacity of the plant and make it more difficult for pH to drop quickly and to a level low enough to stop microbial fermentation. In addition there was potential for microbial residues on the corn plants.

Depending on the types of microorganisms present, there could have been effects on silage fermentation and (or) there could be direct threats to animal health (because of pathogenic organisms) during feed out. After the hurricane, the FDA advised producers to avoid harvesting crops for animal feed that had the potential for contamination from sewage, heavy metals, pathogens, and industrial chemicals. However, allowances were made based on a farm-to-farm basis with recommendations for segregation and monitoring of contaminated feed. In addition to the possible contaminants listed above, there was concern over high ash and microbial laden plants causing abnormal silage fermentations that might compromise the nutritive value of the crops. For example, the high buffering capacity of alfalfa accompanied with high moisture content at ensiling increase the probability of a clostridial fermentation. Poor fermentations are also subject to high incidences of Listeria in silages. The potential for increased loads of mycotoxins in harvested plants was also a concern because of physical damage to the plants allowing for fungal growth.

Materials and Methods
Extension and industry personnel will collaborate and identify farms whose corn silage was compromised due to lodging and/or flooding as a result of Hurricane Irene.

Approximately 75 affected silages and 25 unaffected corn silages (serving as controls) that have been ensiling for a minimum of 60 days and not more than 180 days will be collected. If possible, control samples should be collected from farms submitting affected silages or from farms in the same region.

All samples will be sent to Cumberland Valley Analytical for the following analyses:
1) Standard wet chem: DM, CP, SP, ADF (ADFom*), ADL, NDF (NDFom*), starch, sugar, ash, Ca, P, Mg, Na, Fe, Mn, Zn, Cu
2) In vitro NDF-D (NDF-Dom*), 30 h
3) Yeast and molds
4) Silage fermentation analyses: Lactic acid, VFA, titratable acidity, CP equivalent from ammonia, and ammonia N as a percentage of total N
5) Heavy metals: aluminum, antimony, arsenic, barium, boron, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, mercury, molybdenum, phosphorus, potassium, selenium, sodium, sulfur, thallium, zinc
6) Mycotoxin panel: Aflatoxin B1, B2, G1, G2, Deoxynivalenol, Zearalenone, 15 Acetyl- Don, 3 Acetyl-Don and T-2 Toxin
*analyses to be corrected for ash and presented on an organic matter (om) basis

Cumberland Valley Analytical will subsample each silage and send a representative sample to the University of Delaware for the following analyses:
1) Volatile organic compounds using a solid-phase microextraction (SPME) protocol (Figueiredo et al., 2007) or comparable technique.
2) Qualitative analysis for Escherichia coli O 157, Listeria spp., and Salmonella spp. using a lateral flow technique (Strategic Diagnostics Inc., Newark, DE), All samples will need to clear submissions through the University of Delaware before being sent to Cumberland Valley.

 
Click here for a PDF version of the full proposal.



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Last modified March 09 2012 11:38 AM

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