“STRATEGIES EXIST FOR COPING WITH POOR QUALITY GRAIN: PART 1”
In January, 1997 Dr. Orlando Osuna and Dr. Richard Miles were coauthors of an article published in a special issue of Feedstuffs, the weekly newspaper for agribusiness. Their article, cited below, was selected as the “feature article” in this special issue of Feedstuffs which was published during the week of the annual International Poultry Exposition in Atlanta, Georgia (USA) because it contained valuable information which could be used immediately by the world- wide feed and poultry industry about how to handle and cope with poor quality grain, especially grain contaminated with molds and mycotoxins. Since, this Feedstuffs article was so well received by the world-wide feed and poultry industries and the strategies defined and discussed in the article for dealing with poor quality grain remain relevant today, this issue and the next two issues of Milwhite’s Journal are dedicated to presenting this valuable information to our clients. The information presented will make it evident how important it is for feedmill managers, nutritionists, quality control personnel, veterinarians and poultry production managers to work as a team to establish company guidelines for storing and segregating their incoming shipments of grain. In so doing, good quality grain can be protected and by utilizing the strategies outlined in the article, the negative effects that poor quality grain are known to have on poultry performance will be able to be minimized so that as much as possible of the bird’s genetic potential for performance will be realized.
QUALITY CONTROL-THE FEEDMILL
The quality of raw materials used for feed production by poultry feedmills is of extreme importance because what birds eat can affect flock quality and the wholesomeness of a flock’s meat and eggs. Most raw materials used as an energy and/or protein source in poultry diets are grown, harvested, processed and transported by someone not involved with the poultry industry. Therefore, the feed ingredient quality control component of a poultry operation’s feedmill is an important first step in protecting the birds on the farm. No universal quality control program is best for all feedmills because each feedmill presents a unique management situation. However, some commonalities exist in all feedmills. One commonality is a lack of uniformity in the grain received regardless of its source. Consequently, the quality of the grain is variable with regards to its nutrient content and amount of physical, chemical and/or microbiological contamination. During the past 40 years, Drs. Osuna and Miles have had countless opportunities to visit feedmills and poultry production facilities throughout the world. They both agree that one of the most common problems that existed was related to grain and feed handling and making meaningful decisions when molds and mycotoxins were involved. In many instances they have encountered situations in which mycotoxins, at low concentrations, were present and there was no developed and/or implemented strategy to cope with them in a satisfactory manner. Most birds housed under commercial conditions are more commonly subjected to chronic low level exposure rather than acute high level exposure to mycotoxins.
ENEMIES OF GRAIN DURING STORAGE
There are numerous excellent articles written on how poor quality grain influences poultry health and performance. However, it is essential to understand that there are a multitude of factors that have an influence on the quality of grain once it is stored in silos. These factors cannot be considered alone because they are all interrelated. Without an understanding and an appreciation of these interrelationships it is nearly impossible for anyone to implement strategies to adequately control the deterioration of stored grains which is caused by molds. One of the major strategies to control grain deterioration during storage is to control the moisture in the grain. Moisture is the number one enemy of stored grain and proper grain drying is essential. If moisture is controlled, mold growth is controlled and mycotoxin production is usually not a problem, unless the grain contains mycotoxins that have been previously produced by the molds. Consequently, many feedmills focus the majority of their efforts in prevention of mold growth during grain storage. Even if the number one enemy of grain is known to be moisture, the role that insects and rodents play in causing mycotoxin and other quality control problems must not be overlooked. Insects and rodents lead to the production of “fines” (dust) by compromising the structural integrity of the grain kernel. Any decrease in kernel integrity will increase the possibility of eventual mold and/or bacterial contamination. Dust is known to be a food source for insects and rodents and a major source of salmonella contamination in feedmills and every attempt should always be made to control dust formation and its accumulation in and around feedmills. In addition, controlling rodents will decrease the likelihood of fire and dust explosions due to the damage that rodents cause with electrical wiring. Air quality is also enhanced when dust is controlled and controlling dust decreases respiratory problems which are known to occur in feedmill employees continually exposed to dust. Some of the best and most expensive mold preventive measures designed for stored grain often fail because an integrated pest control and sanitation program has not been developed simultaneously. Feed bin cleanliness should be monitored on a regular basis. Grain storage bins, their boots and all associated augers should be included as an essential component of a company’s Hazard Analysis and Critical Control Point (HACCP) program. Immediate clean- up should always follow a feed and/or oil spill and unsanitary conditions around the feedmill should be rectified in a timely manner.
REQUIREMENTS FOR MOLD GROWTH
Molds are ubiquitous and prior to harvest there is presently no practical way to prevent their presence or the presence of their spores. So, there will always be a threat of mycotoxin production in grain prior to harvest when favorable environmental conditions exist that promote mold growth. This is why pre-harvest mycotoxin concentration varies in grains from year to year, especially when environmental stressors such as drought and insect damage are high. Often, a company does not know the geographic origin of their grain. Knowing the location would prove beneficial during the screening for certain mycotoxins. For example, it is known that aflatoxins tend to predominate in grain that is grown in warmer climates and has a higher oil content such as corn instead of wheat and oats since aspergillus thrives on high oil grains. Grain originating in cooler climates is usually associated with contamination with Fusarium toxins such as fumonisin, deoxynivalenol and zearalenone.
Mold growth is associated with five factors: a nutrient source (the grain), moisture (usually above 12%), warm temperature, oxygen and time. As molds grow, hair-like structures known as hyphae immediately cover and penetrate the grain. Digestive enzymes are released from the hyphae and the nutrients are broken down and absorbed and utilized by the mold. Molds are heterotrophs, just like animals, and require preformed organic compounds as an energy source. Therefore, the carbohydrate, fat and protein are able to be utilized for energy. This is why grain subjected to mold growth is associated with less metabolizable energy. Once grain arrives at a feedmill and is placed in a storage silo its quality begins to decline as long as the grain remains in storage. Grain quality does not improve during storage. The best that can be expected is for its quality to be maintained for as long as possible until it is used in feed formulation. The rate of deterioration will depend on grain management practices that a company has incorporated into their quality control program. Therefore, purchasing high quality grain is most desirable and minimizing its deterioration during storage should always be major objectives. In the next issue of Milwhite’s Journal strategies will be discussed that have been shown to minimize the rate of grain deterioration during storage.
The information presented in this issue of Milwhite’s Journal was compiled by Dr. Orlando Osuna, Director of Health Services at Milwhite, Inc. and Dr. Richard Miles, Professor Emeritus, Univ. of Florida, Gainesville, FL, USA.
Osuna, O. and R.D. Miles. 1997. Strategies exist for coping with poor quality grain. Feedstuffs. Jan.20, Vol. 69:no.3.