Use of Ammoniated Corn in Feed Rations at a Commercial Feedyard:

An Industry Report⁽¹⁾

Lawrence Falconer and Rick Jahn

Extension Economist-Management and San Patricio/Aransas CEA-AG

Texas Agricultural Extension Service

August 7, 1996

Introduction

The use of ammoniated corn in rations for beef cattle at commercial sized feed yards (over 1,000 head capacity) has not been a wide spread practice in South Texas in the past. However, the market conditions and significant amounts of corn with aflatoxin contamination that existed during the summer and fall of 1995 provided an opportunity to assess the technical and economic feasibility of feeding ammoniated corn to steers and heifers on a large scale basis. This report is intended to provide information from data gathered from a large scale ammoniation process and the subsequent performance of cattle fed ammoniated corn. The primary information for this report was provided by personnel of the Edroy Grain Company, Edroy, Texas and Howell Cattle Company, Premont, Texas.

Under certain growing conditions, aflatoxin contamination can occur in a sizable amount of the corn produced in South Texas. Aflatoxins are toxic compounds that are produced by Aspergillus flavus and Aspergillus parasiticus fungi. Cattle that consume high levels of these toxins can develop various health problems, ranging from appetite suppression to liver damage (Valco).

Current regulations governing the export and human consumption of corn places an upper limit on aflatoxin contamination in corn at 20 parts per billion (ppb). For purposes of feeding corn to young growing/finishing cattle, test results of less than 100 ppb are considered acceptable (Jones). Technically speaking, corn with aflatoxin contamination above 300 ppb has no market value as feed.

During the 1995 crop year, aflatoxin levels for corn tested at the Corpus Christi Grain Exchange ranged from 200 to 1000 ppb, with the majority of test results falling into the 200 to 400 ppb range (Livingston). Historically, there have been three primary methods used to deal with the aflatoxin contaminated corn. These methods include: 1) crop destruction, 2) attempting to clean the contaminated corn through gravimetric methods, and 3) ammoniation.

In the case of extremely low yielding corn that also has aflatoxin contamination, producers have resorted to crop destruction. This option is often unattractive, as crop insurance indemnities are low in relation to cost of production and production potential in South Texas.

Gravimetric methods are primarily separation of the lighter fragments from heavier fragments through shaking on series of tables and screens. The lighter, damaged fragments are separated via air and mass, often reducing the aflatoxins to acceptable levels.

Corn contaminated with aflatoxin can also be treated with ammonia to destroy the toxins. Temperature, time of exposure and kernel density effect the completeness of the process. Because of the ammonia odor and discoloration (carmelization) caused by the ammoniation process, the treated corn becomes "sample-grade". Previous to the 1995 crop year, large scale ammoniation treatments of aflatoxin contaminated corn were not employed in South Texas.

Ammoniation Process and Results

During the late summer and fall of 1995, 15 million pounds of corn that were tested for aflatoxin and found to be contaminated in excess of 300 ppb were treated with ammonia at the Edroy Grain Company, Edroy, TX (Figure 1). This proprietary treatment consisted of exposing the corn to a high temperature and high pressure process while introducing ammonia to the corn. The equipment and process used to ammoniate the corn was leased from Walker Cottonseed Company of Casa Grande, Arizona.

Test results carried out by Howell Cattle Company after ammoniation showed aflatoxin levels averaging 27 ppb, well within acceptable levels for feeding to growing/finishing cattle. The ammoniation process was also credited for increasing average crude protein levels of the corn from 9.0% to 12.5%.

One effect noted was that corn with pre-ammoniated moisture levels of less than 12.5% were tested at levels as high as 17% post-ammoniation, while only about 2.5% water was added per cwt of corn in the ammoniation process. It was suspected that the presence of free ammonia in the treated corn led to errors in moisture readings using conductivity type moisture tests. To test this idea, one batch of corn was ammoniated with no moisture added. Moisture levels from the standard conductivity tests made prior to ammoniation of this test batch were then compared with the moisture level reading after ammoniation. The readings from this test batch tended to confirm that the conductivity testing method overstated moisture levels in the treated corn by approximately 2.5%. These results were also confirmed by laboratory testing carried out for Howell Cattle Company.

Edroy Grain Company personnel report that immediately after ammoniation, corn placed in galvanized storage tanks caused some condensation during the cooling period, causing some discoloration on the grain storage tanks. With this exception, the ammoniated corn caused no other handling problems in the short time it was stored. However, no information is available from this study on the effects of long term storage of ammoniated grain on storage tanks. It was also found that the ammonia odor of freshly treated corn makes storage of these products near residential areas undesirable.

Feeding Program Results

The product was transferred to Howell Cattle Company at Premont, TX. for processing into the cattle feed rations. The ammoniated corn underwent a standard steam flaking process prior to mixing with other ration ingredients. During the period of November 21, 1995 to the end of March 1996 , over six thousand head were fed rations containing ammoniated corn.

Howell Cattle Company personnel reported few handling problems with the ammoniated corn. The corn gave off a very strong ammonia odor during steam flaking and care was taken to provide adequate ventilation or personal safety equipment during that process. After steam flaking the corn, the ammonia odor subsided. The steam flaking process apparently displaced some of the impregnated ammonia, leading to small losses of crude protein gained in the ammoniation process.

The cattle being fed the rations containing ammoniated corn showed no adverse reactions to the product. Previous experience shows that the cattle would go off-feed within two to three days if the aflatoxin was present. Howell Cattle Company personnel reported no drop in feed consumption, or any other health or performance problems that could be attributed to the ammoniated corn.

Clinical chemistry tests were performed on the cattle by Dr. Jim Sheldon, the consulting veterinarian for Howell Cattle Company. These tests included liver function tests, and showed no negative effects from the feeding of ammoniated corn. These tests results indicate that there were no carryover effects of the aflatoxins that had been present prior to ammoniation. These results were the basis of cautious optimism for the use of ammoniated corn as feed for young adult and adult beef cows expressed by Dr. Sheldon.

Table 1 shows average daily gains and dry matter feed conversion ratios for a representative sample of cattle that were fed rations containing ammoniated corn at Howell Cattle Company. The performance of the cattle being fed rations containing ammoniated corn was deemed to be satisfactory by Dr. Alejandro Urias, consulting animal nutritionist to Howell Cattle Company.

Sex	Head	In Date	Out Date	In Weight	Out Weight	Average Daily Gain	Dry Matter Conversion
Steers	190	7/17/95	2/23/96	514	1084	2.95	6.45
Steers	141	9/20/95	2/15/96	596	992	2.68	6.62
Steers	186	10/17/95	3/14/96	701	1147	3.03	7.11
Steers	144	10/31/95	3/27/96	643	1042	2.69	6.77
Heifers	121	8/24/95	2/14/96	545	1008	2.64	6.60
Heifers	190	8/25/96	2/1/96	605	1027	2.52	6.80

Table 1. Performance measures for representative lots of classes of cattle fed rations containing ammoniated corn at Howell Cattle Company, Premont, TX.

Economic Implications

Previously in South Texas, corn that tested over 300 ppb had no market value. Based on the information collected for this report, a properly applied ammoniation process appears to be a viable method for reducing aflatoxin contamination to levels well within standards deemed to be safe for cattle feed. Treatment costs for ammoniation were $1.00 per cwt, plus handling charges ranging from 25 cents to 30 cents per cwt. It is likely that ammoniation costs can be lowered through economies of size. With increased throughput, it is estimated by Edroy Grain Company personnel that treatment costs might also decline.

The value of the ammoniated corn to cattle feeding operations would appear to be very close to #2 yellow corn, given the results seen at Howell Cattle Company in late 1995 and early 1996. However, due to the odor and discoloration caused by the ammoniation process, it is not possible for the treated corn to command a price equal to non-contaminated #2 yellow corn. It is likely that the ammoniated corn would be priced near the levels of the closest substitute, which in most cases in Texas would be grain sorghum. The "normal" price differential for #2 yellow corn and grain sorghum is estimated at 20 to 40 cents per cwt at South Texas elevators.

Conclusion

The results from a commercial size effort using ammoniation to detoxify corn that was contaminated with excessive levels of aflatoxin carried out in late 1995 and 1996 were successful. The treatment process consistently reduced aflatoxin levels in contaminated corn from above 300 ppb to less than 30 ppb. The subsequent use of the ammoniated corn in feed rations also proved to be successful. Clinical chemistry results showed no negative effects from the feeding of the ammoniated corn. Performance as measured by average daily gain and feed conversion for cattle fed rations containing ammoniated corn was deemed to be acceptable. The economic consequences of applying this technology was that corn with no technical market value was salvaged, with the potential to command prices that justified treatment costs.

References and Suggested Further Readings

Horne, C. Wendell. "Mycotoxins in Feed and Food-Producing Crops.", Texas Agricultural Extension Service Bulletin B-1279, College Station, TX, January 1991.

Jones, Frank T. "Understanding and Coping With the Effects of Mycotoxins in Livestock Feed and Forage.", North Carolina Cooperative Extension Service, Electronic Publication Number DRO-29, Raleigh, North Carolina, December 1994.

Livingston, Steve. "Current Aflatoxin Testing Situation in the Texas Coastal Bend.", unpublished manuscript, August 1995, Texas Agricultural Extension Service, Corpus Christi, TX.

Valco, Thomas D. "Ammoniation of Aflatoxin-Contaminated Corn", Texas Agricultural Extension Service Bulletin L-2459, College Station, TX, December 1990.

1. Thanks is expressed to Mr. Sid Brough of Edroy Grain Company and Mr. Jesse Howell of Howell Cattle Company for their help in gathering and reviewing the information in this report.