AS-349 August, 1966

Good Feed Mixing Practices
D, R. Zimmerman. Animal Sciences Department
The days when feed was mixed with a scoop-shovel are long gone. Modern formulas include minute amounts of trace minerals, vitamins, and drugs. A careful job of mixing must be done to get equal distribution of all ingredients throughout a batch of feed.
Poorly mixed feeds may result in inferior animal performance, wasted microingredients, illegal drug residues in animal products, or even death. The farmer who is interested in obtaining the maximum return on money spent for feed and in producing quality animal products will make sure his feed is adequately mixed.
Proper mixing is dependent on a number of factors. Many of these factors are listed and discussed in the following paragraphs.
Buildings and Housekeeping
Feed handling and mixing facilities must meet certain basic requirements. However, they needn't be elaborate and expensive. All facilities must be weather-tight. Rodents must be controlled in ingredient storage areas. A separate room or enclosed area should be used for storage of feed additives and premixes. The areas where ingredients are weighed and mixed should be well lighted. The floors should be smooth and solid to facilitate sweeping.
Actions speak louder than words! In almost every instance the man who takes pride in the appearance of his feed mixing facilities, will make accurately formulated, well mixed feed.
Piles of spilled feed, dust and empty bags attract and harbor rodents and insect pests.
Floor sweepings should either be added to the immediate batch of feed being prepared, or they should be destroyed. Once sweepings are allowed to accumulate, their identity is lost. Adding them to a later batch of feed may contaminate the feed with unwanted ingredients .
Weighing
Weighing must be done on scales that are of adequate sensitivity. One pound of an ingredient cannot be weighed precisely on a scale having pound or half-pound marks as the smallest graduations. The scale must be of such sensitivity that a difference of plus and minus two percent of the item’s weight can be measured. For example, if an item weighs five pounds, the scale used to weigh it should be graduated in tenths of a pound.
Scales should be maintained and checked periodically for accuracy with a set of standard weights. The weight pan or platform should be kept clean. This is important not only for accurate weighing but also to prevent contamination of the following batches.
When calculating the amount of drug or vitamin premix to add to a batch, it is sometimes necessary to make conversions such as from grams to pounds, and from percent to grams per ton. Also, in many cases one —-must account for a "dilution factor. Vitamins and drug products are rarely one-hundred per cent active material.