Feed formulas used on most swine operations come from three sources: feed tags, consultants, and university extension or research. Formulas from feed tags are very general. They often list "grain," rather than specific grains such as corn, wheat, and grain sorghum. These formulas contain a safety margin to reduce the problems caused by below average nutrient content in an ingredient.
Most other formulas are specific, not to one grain, but to one load of that grain. These are based on the analyzed nutrient content of each ingredient to be used. Specific formulas should meet the pigs' requirements with little or no margin for error.
A formulation for a specific class or weight of pigs must be used for those pigs only. For feed company recommendations, follow the instructions on the feed tag as closely as possible. Only use a feed ingredient designed for one class of pigs at a specific rate per day as it was intended.
A common practice is to add ingredients that are not in the formula. Any non-nutritive additives such as antibiotics should not cause any problems. Adding other products such as mineral mixes can result in a poor finished product. The producers who think their hogs require more nutrients or higher levels of some nutrients than a commercial product or a custom formula supplies should find another commercial product or formula that better suits their needs.
To ensure that feed formulations are not causing problems on your farm, keep these points in mind: