Efficient animal feed storage, preservation tips

The best measure against the deterioration of feed quality is prompt incorporation of high quality raw materials in diets that are rapidly consumed after manufacturing.

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The best measure against the deterioration of feed quality is prompt incorporation of high quality raw materials in diets that are rapidly consumed after manufacturing — always under strict conditions of hygiene and safety in the feed mill, during transportation and storage, and at the animal/farm level. But, when prolonged storage of finished products is expected, either at the mill or farm, then feed preservatives are often used to guard quality. Feed sanitization by exposure to high temperatures or irradiation is frequently used to reduce microbial load and prolong the shelf-life of ingredients and finished products.

Storage of raw materials

Proper storage of raw materials and finished products affects their nutritive value in many ways. First, prolonged storage, even under ideal conditions, involves slow but continuous proliferation of bacteria, insects and molds that naturally exists in most raw materials. At the very best, these contaminating organisms consume nutrients. In most cases, however, they also produce toxins (such is the example of mycotoxins) that severely impair animal performance, and when in large concentrations, even animal health. Second, under hot and humid conditions, not only does the growth of such pests accelerate, but Maillard reaction products (browning reaction) are rapidly formed, further reducing nutritive value. Third, objectionable flavors may develop mainly but not exclusively due to unavoidable lipid rancidity (stale feed). Fourth, several vitamins, enzymes and other chemical compounds sensitive to heat and oxygen rapidly lose potency, especially when mixed with oxidative trace minerals and exposed to high temperatures during storage.

Especially during the warm months of the year, it is advised to use complete diets and premixes within two months of production, if possible.

Most raw materials have a shelf-life that ranges from a few months to one year. Uncontaminated raw cereals and protein-rich ingredients may be stored even longer under appropriate conditions with minimal loss of nutritive value. But complete diets and premixes usually have a shelf-life of about three months or less, depending on composition and storage conditions. Especially during the warm months of the year, it is advised to use complete diets and premixes within two months of production, if possible.

It is common practice in some operations to store bags of young animal diets inside the animal barn. This practice exposes a diet, often rich in reducing sugars and amino acids, to high levels of humidity and heat, commonly encountered in commercial facilities for young animals. This has a severe impact on feed quality. For example, when such sensitive and expensive feed was stored for seven days at 28 C and 90 percent relative humidity, lysine bioavailability decreased by 10 percent, indicating the vulnerability of such diets and nutrients. In other words, 10 percent lysine was wasted in only a week when feed was kept at the same conditions as the animals experienced. Comparable results should be expected when diets are stored in warm, and especially humid, warehouses for prolonged periods of time. The old advice of storing valuable products under dry and cool conditions remains valid, yet more often than not is largely ignored by the majority of farms.

Preservation

Elimination of Salmonella in animal feed remains a pressing issue, especially in production systems that do not use growth-promoting levels of antimicrobial agents. This is important to safeguard both animal health and food/human safety. To this end, steam-heating of finished feed has been applied with success. For example, it has been reported that Salmonella elimination was achieved by steam-heating meal diets to 85 C for 4 minutes in a heated mixer. Of course, such high temperatures for such prolonged expose time wreaked havoc to sensitive nutrients such as amino acids and vitamins.

Pelleting at 85 C also achieves reduction or even elimination of Salmonella in finished products. Again, overheating reduced nutritive value and as such, a balance between feed sanitation and nutritive balance is preferable but not always possible. To this purpose, heat-sensitive materials that are naturally free of Salmonella (vitamins, enzymes, etc.) may be added after heat treatment, whereas the extra cost of treatment should be weighed against benefits. Organic acids may also be used effectively against Salmonella proliferation in feeds as an alternative or supplement to heat treatment.

Learn more: How to control oxidation in finished feeds

To prevent lipid oxidation in finished products, antioxidants are usually added. This is common practice in warm and humid climates, during the summer and for products destined for export (long interval between production and consumption). Most common antioxidants include butylated hydroxyanisol (BHA), butylated hydroxytoluene (BHT) and ethoxyquin. Vitamins E and C are also examples of organic antioxidants that are rapidly consumed/wasted if chemical antioxidants are not included in sensitive feeds.

The addition of clays and other mycotoxin binders does not check mold growth, but rather reduces the impact of toxins ingested by animals.

To prevent mold growth and production of mycotoxins, propionic and other organic acids are frequently added in finished products. Because liquid propionic acid is highly corrosive, powdered propionic acid on carriers or buffered propionic acid products are preferred from a manufacturing standpoint. Usually, 0.1 percent propionic acid is enough to safeguard against mold growth under most conditions, but up to 0.5 percent may be essential in very humid climates. Because propionic acid is an organic acid, it may also act as an antimicrobial agent at the intestinal level, but such effects are usually observed at rather high concentrations. Of course, other organic acids (e.g., sorbic or benzoic) are often used instead or in conjunction with propionic acid. The addition of clays and other mycotoxin binders does not check mold growth, but rather reduces the impact of toxins ingested by animals.

Safeguarding feed quality

Feed quality is safeguarded starting at feed design/formulation stages, continues through manufacturing and storage and does not end until animals finally consume (or not) the finished product. Adding several additives and treating feeds may prolong feed quality, and these measures should be considered supplementary to good hygiene conditions at feed and farm level.

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