In part one of this overview, SDSU Extension swine specialists Bob Thaler and Ryan Samuel, explain the differences in nutritional makeup of Light-Weight Corn (LWC) and feeding guidelines. Ahead, mycotoxins and bulk density of this corn will be reviewed.
The weather conditions that stress corn are the same conditions that make the corn susceptible to mold growth and mycotoxins. Producers need to keep two points in mind when thinking about mold and mycotoxins, the article notes.
The first is that mold produces mycotoxins and these mycotoxins that can be detrimental to pig performance. The second is that not all molds are bad. Some look bad but have no detrimental effect on pig performance.
In the U.S., the main mycotoxins that affect pigs are aflatoxin, zearalenone, vomitoxin or deoxynivalenol (DON) and fumonisins.
Once corn is contaminated with these mycotoxins, very little can be done to remove or inactivate them. According to the article, pellet binders have been shown to reduce the impact of aflatoxins, but there are few products that consistently inactivate other mycotoxins. Mold inhibitors can be added to prevent new mycotoxin production, and mycotoxin binders and adsorbents can be added to the diets to potentially lessen the impact of mycotoxins.3
The first step in dealing with mycotoxins is to determine which one(s) are present and at what level. Samples should be taken from at least 10 different locations in the bin or truck, mix the samples and then send a representative subsample in a paper or cloth bag to a certified lab for a mycotoxin screen. The authors note that mycotoxin production in a corn field is extremely variable, and it can be difficult to get a representative sample.
Once the type and level concentrations of the mycotoxins in the LWC are known, the producer can develop a plan on how to use them in their feeding program.
Impact of bulk density of weather-stressed corn
Since LWC has a lower bulk density than normal corn, that can impact feed mixing, delivery and storage. It takes fewer pounds of LWC to fill up a given volume than heavier, denser #1 corn, the article notes.
For example, 4,000 lbs of 56 lb corn will fill a two-ton mixer, but it only takes 3,575 lbs of 50 lb corn to fill that same volume.2 Therefore, it is essential that LWC be added to the mixer based on weight, not volume, to get the right amount of corn in. When using an auger system to mix feed, producers will need to recalibrate their auger when using LWC to make sure it is adding the correct amount of corn to the diet.
The other issue with lower density LWC is that it reduces the number of tons of feed that a feed truck can haul, and also the amount of feed that can be stored in bulk bins. When first using LWC, it is critical that the feedmill understands what these differences mean to feed manufacturing and transportation, the article advises.
1. Johnston, L. 1995. Use of low-test-weight corn in swine diets and the lysine/protein relationship in corn. Swine Health and Production vol 3(4):161.
2. Thaler, R.C. and D.E. Reese. 2010. Utilization of weather-stressed feedstuffs in swine diets. Chapter 24 - National Swine Nutrition Guide, D. Meisinger, Editor. 2010. US Pork Center of Excellence.
3. Menegat, M.B., R.D. Goodband, J.M. DeRouchey, M.D. Tokach, J.C. Woodworth, and S.S. Dritz. 2019. Kansas State University Swine Nutrition Guide: Mycotoxins in Swine Diets.
More from Farm Journal's PORK: