Feed & Feed Additives

by Dan Loy, Ph.D., Department of Animal Science, Iowa State University

They Are What They Eat

The first step to feed quality management for beef quality assurance is the constant recognition that everything that enters the animal through feed sources has the potential to show up in the beef produced as an end product. This includes herbicides and insecticides used to grow the crop, bacteria and natural organisms that may grow in the course of feed storage, fluids leaked from feed processing equipment and for contamination to the extent of producing violative residues are rare. However, adopting a philosophy that they can occur and looking for critical points in the production process where mistakes could happen makes much of the feed quality control process a simple matter of common sense and routine checks of the system.

Feedstuffs and Sources

Many beef producers in Iowa produce the majority of feeds fed to their cattle on their own farms. Quality control is much easier when you have complete control of the feed production process. Most herbicides and insecticides, when used on crops according to the guidelines on the label provide a safety margin against the potential for causing harmful residues in beef. Producers should be aware of label restrictions for feeding or grazing of crops after treated with pesticides. Under certain conditions, such as drought, hail, flood, etc., crops that were originally intended for harvest as grain for example, may be best salvaged as a forage crop. It is imperative that the labels for any pesticides used are reviewed before any salvage harvest or grazing is done.

Using good management practices in the storage and processing of homegrown feeds reduces the potential for contamination by natural toxins. Harvesting and storing feeds at the correct moisture level, using good silage management and storage techniques not only help prevent contamination by molds, mycotoxins and pathogenic bacteria, but improve feed efficiency and lower cost of production.

Purchased feeds

Quality control in purchased feeds includes analysis of incoming ingredients and using select suppliers that have quality control programs in place and stand behind their products. Evaluation of feed quality differs with different ingredients. Some ingredients are naturally more perishable and higher risk than other feed ingredients. As a start, most incoming feed ingredients should be evaluated for moisture, color, odor, texture, presence of foreign material, heat damage and mold or other spoilage. Presence of any suspected problems in these areas may require further testing for heat damage, mycotoxins, ash, etc. You may also choose to routinely sample and test incoming feeds for nutrient analysis to aid in diet formulation. Keep a sample of suspected feedstuffs for later testing. Feed fats should be routinely analyzed for moisture, free fatty acids, rancidity and impurities. Or, purchase your feeds from a reliable source that guarantees routine tests and proven production methods are used. Ruminant derived animal protein feeds should never be fed to cattle under current law.

Feed storage, processing and handling

Feeds should always be handled in a way that ensures that contamination does not occur. Equipment such as endloaders that are used for loading feed should be routinely inspected for leaks in hydraulic or fluids. These fluids can be toxic if ingested and pose a residue threat. Clean tractor wheels and loaders before using them for feed handling or packing silos. Feed handling and mixing equipment should also be routinely inspected for fluid leaks and maintained properly. Never store crop chemicals, petroleum products or other potentially hazardous material in areas where feed is stored, mixed or processed.

Feed Additives

The use of medicated feeds for livestock is regulated by the U.S. Food and Drug Administration. Feed mills that mix certain supplements and premixes are required to register with the FDA and are subject to routine inspections. Other feed mixing facilities including on-farm mixing facilities are not required to register with the FDA, but are required to follow current good management practices. In other words, if you mix feed on the farm that contains feed additives, you must follow FDA’s CGMPs. CGMPs include the following:

1. Facilities and equipment should be constructed and maintained to minimize vermin and pest infestation, allow proper maintenance and cleaning, accurately produce feed of intended use and prevent accidental contamination from fertilizers, pesticides or other contaminants.

2. Quality assurance of feed products through identification, storage, inventory control, documented corrective actions and adherence to label instructions.

3. Proper equipment cleanout procedures to prevent carryover.

4. Proper labeling and complete records of feed formulations, mixing and deliveries.

A more complete document outlining CGMPs for non-registered feed mills is available from the FDA.

Implants

The FDA also regulates implants. Currently, no implant cleared for use in beef cattle in the United States has a withdrawal time required by the FDA. However, there is no economic incentive for implanting cattle less than 45-60 days prior to slaughter.

All implants that are currently used should be placed in the middle 1/3 or the ear. Note the illustration in Figure I. of this page. Placement of implants closer to the base of the ear increases the risk of implant residue remaining in edible tissues.

Proper implanting technique ensures optimum growth response and a higher return per dollar invested in implants. Several of the companies that manufacture implants have developed excellent programs for evaluating implant technique. This includes proper placement and technique that reduces the possibility of infections that reduce implant performance.

Dark Cutter Research

Abstracted by Eldon J. Hans, Past BQA Coordinator for ICA

Based on Colorado State University research, the incidence of “dark cutting” cattle was influenced by several factors. Those included the sex of the animal, implant treatments, days from final implant to harvest, temperature fluctuations from two days before harvest to the day of harvest, and the feedyard itself.

Heifers yielded a higher percentage of dark cutters per pen and when re-implanted a second time with an estrogenic implant, produced greater average percentages of dark cutters per pen than heifers reimplanted with either androgens or combination (androgen and estrogen) growth promotants. Furthermore, heifers produced a higher average percentage of dark cutters per pen than steers during periods of hot weather (95° F and over), one to two days before harvest. Steers, when treated with a combination (androgen and estrogen) implant when entering the feedyard and a reimplant later produced higher average percentage of dark cutters per pen compared to more moderate growth promoting implant strategies. When producers opted to implant steers with estrogenic growth promotants, either as cattle entering the feedlot or as a final implant preharvest, the occurrence of dark cutters was reduced from 9.2 per thousand cattle shipped to 2 and .5 per thousand cattle shipped respectively. Producers reimplanting heifers before harvest with products that were not primarily estrogenic reduced the occurrence of dark cutters from 10.4 per thousand cattle shipped to 5.2 per thousand cattle shipped when combination (androgen and estrogen) implants were administered. Producers holding cattle on feed over 100 days past implantation reduced incidence of dark cutters per pen an average of 38 percent among heifers and 69 percent among steers.