Having the right ingredients is important for every recipe. Of course this is true even when you’re mixing swine feeds.

To demonstrate the need to find the right mix, Kansas State University researchers, led by Crystal Groesbeck, research assistant, conducted two experiments that looked at salt as a mixing compound. They evaluated different particle sizes and preparation methods (unground salt at 730 microns or ground salt at 440 microns) on mixing efficiency.

Researchers used a 3,000-pound-capacity horizontal ribbon mixer to mix batches of feed. They collected 10 samples at eight times during the mixing process from pre-determined locations in the mixer to measure its efficiency.

In the first experiment, researchers prepared four 3,000-pound batches of feed, two with 440-micron salt and two with 730-micron salt. They analyzed both unground and ground samples, but found that all of the feed batches were inadequately mixed.

In the second experiment, researchers collected samples from 2,000-pound batches of feed made in the same 3,000-pound-capacity mixer. They analyzed four sizes of unground and ground salt particles. The studies’ results show that as salt-particle size decreased and mixing time increased, the result was a more uniform feed mixture.

Overall, these two experiments point out that salt size is important for an efficient and effective feed mixture, as is the amount of grinding time. It’s important to use a fine-mixing salt. If you use salt that’s too coarse, you will end up with misleading results,” says Mike Tokach, Kansas State University swine nutritionist.

Also when the mixer is filled to the rated capacity, the batches may be too large to mix efficiently. “If you overfill a mixture, it simply won’t do an adequate job,” he adds.

Keep in mind, that salt isn’t the only ingredient that can be used to measure mixture efficiency. Some people use selenium or zinc. Tokach says the Kansas State researchers chose salt because it’s cost effective.

Another reason producers should be concerned about mixture efficiency is that pig performance — especially in the nursery — is hurt when feed ingredients aren’t mixed properly. Tokach points out that producers are using smaller-inclusion-rate products today, such as synthetic amino acids, which make it essential to have a well-mixed diet. There’s certainly more potential performance fallout if pigs don’t get the right mix of these ingredients. 

For example, a typical use rate for synthetic lysine is 3 to 6 pounds per ton, while you would use up to 3 pounds per ton of threonine, and only 0.5 to 1 pound of methionine per ton of feed. It’s important to get proper amounts of those amino acids into all pigs for adequate growth.

“In the many trials looking at mixture efficiency,” says Tokach. “we’ve found that if you don’t adequately mix diets in the nursery, it can reduce the pigs’ average daily gain and feed efficiency rates by 10 percent to 25 percent, depending on how bad the mix was.”

But along with monitoring your mixture efficiency, Tokach says it’s essential to use an accurate lab for the analysis. Talk to other producers, swine nutritionists, your local or state Extension representatives about which laboratories have a reputation for being thorough and accurate.

Remember, you need to find the right feed mix and amount to get the best growth performance and efficiency from your pigs.