Hogs that are fed the same diet in different locations don’t always get the same level      of nutrients, concludes USDA  Agri-cultural Research Service scientists. They participated in  a collaborative study with 24 universities from the North-Central and Southern regions of the United States, to evaluate the consistency of feed mixtures fed to swine.

Researchers at the ARS Roman L. Hruska U.S. Meat Animal Research Center in Clay Center, Neb., and the university researchers, prepared the same corn/soybean meal diet, fortified with vitamins and minerals, at each location. Samples of each station’s feed mixture were analyzed for crude-protein, calcium, phosphorus and zinc concentrations.

Laboratory analysis showed diets mixed at some locations had higher crude-protein, calcium, phosphorus and zinc levels than those mixed at others.

Part of the variation in crude protein came from the corn and/or soybean meal used at each location. Differences in calcium and phosphorus contents were likely caused by various sources of supplemental dicalcium phosphate used. Variation in zinc concentration was attributed to erroneous amounts of trace-mineral premixes added to the diets. Another reason for variation in calcium, phosphorus and zinc concentrations is that some laboratories don’t routinely conduct mineral assays.

For scientists and technicians, the study’s results illustrate that they should be careful when mixing test diets, and should guard against drawing incorrect conclusions regarding dietary treatment effects. For producers, it means you should not take for granted that the same diet formulation is created equal across different sites.

Note that the diets were not fed to pigs. Researchers mixed the diets to test their hypothesis about the importance and accuracy of diet mixing.