Kansas State University (KSU) researchers say check your sow feed distribution system to ensure sows are actually getting the proper amount of feed.

Pork producers planning to construct new sow barns or replace the feed delivery system in existing farrowing and/or gestation facilities should strongly consider the type of feed drop system they install, urge KSU researchers.

Mike Tokach, Extension swine specialist, and graduate student Jason Schneider, assisted by a team of other KSU researchers, conducted and analyzed results on a series of trials to determine if the angle of feed drops for sows influences the level of feed actually delivered to the feed drop.

“In gestation barns, the feed drops are installed perpendicularly, or at a 90-degree angle,” explains Tokach, thus allowing for the maximum flow of feed from the line into the feed drop. “But over time, from feed lines being stretched or due to changes from the installation of other equipment, many of the feed drops end up at an angle much less than 90 degrees from the feed line.”

Testing Feed Drops

For the study, the KSU team decided to test gestation feed drops at three different angles set at 60, 75 and 90 degrees (Figure 1). The feed drops were measured at delivery rates of 2, 4, 6, 8 and 10 lb. of feed, all using the same corn-soybean meal-based diet, says Schneider.

“The way these feed drops work, the drops are filled from the top of the feed line in a volumetric delivery and the pounds dropped increase linearly as the volumetric setting on the drop increases,” says Tokach.

The most commonly used gestation feed drop is the “box” type. When this type of drop system was tested, KSU research showed that the angle of delivery had a significant impact on the amount of feed delivered to the feeder, says Tokach.

“If all of the boxes are at exactly the same angle, the difference between the volumetric setting and the actual pounds can be measured and dealt with in the feeder settings,” he says. “However, if the boxes are at different angles, it will be very difficult to know the amount of feed dropped for each box because that level will change throughout the barn.”

Especially disturbing is that the level of feed delivered to the feed drop can be above or below the actual predicted value or feed setting, says Tokach.

In the trials conducted, shown in Figure 2, the level of feed delivered when the box drop was at the perpendicular angle was actually more feed than what the setting called for. The bulk density of the diet will also have some influence on the flow of feed through the drop, suggesting that a less dense diet would fall closer to the actual setting, he says.

More of a concern in regards to sow performance is that as feed drops develop more of an angle (less than 90 degrees), less and less feed is dropped.

If the box feed drops were all turned at the same angle, the producer could compensate for this change. But the fact is, they end up at differing angles. This creates a particular problem in sow gestation barns that are 10-15 years old.

“It becomes very difficult in these older barns to maintain the box feed drops at exactly the same angle,” he points out. And once they are out of adjustment, it becomes virtually impossible to return them to their former perpendicular position.

Adjusting Feed Drops

Out-of-alignment gestation feed drops are proving that there is a lot more variation in actual sow feeding levels than was previously thought, Tokach says, based on farms he and fellow KSU researchers have visited.

“And the reality is, most producers don't know exactly how much feed they are dropping. They set it and they think that it's close to the appropriate level. If they do any feed drop measurements at all, they'll do it as they change the bulk density of the diet. They still assume that all of the feed drops in the barn are dropping the same amount (when they are most likely not),” he stresses.

Feed Drops Not Created Equal

Tokach says the lesson producers need to learn is that there are definite differences between types of feed drops. Newer, cylindrical feed drops tested by KSU, depicted in Figure 3, provide a much more precise level of feed to the feeder.

“It seems like a lot of feed equipment companies in the past few years have gone to cylinder feed drops as they are developing newer products for the market,” notes Tokach. “The cylindrical drop amazed me in how well it fit what the feed system called for. It created more consistency, and you can change that feed drop angle between 75 and 90 degrees and still get the same amount of feed dropped into the feeder.”

Tokach says the cylindrical-style feed drop has created a huge innovation in sow feeding. The box-type sow feeder costs $1-2 less, but their research shows that the cylindrical version “should allow you to begin to feed sows more accurately and help achieve the feeding levels suggested for sows based on backfat and weight.” (See “Managing Sows in Gestation,” National Hog Farmer Blueprint series, April 15, 2006, page 18.)

The lactation feed drop tested (depicted in Figure 4) was also shown to be more accurate in feed delivery than the standard box-type design, says Tokach.

He reasons both the cylinder and the lactation feed drops work more consistently in delivering feed because they attach to the feed line differently.

“The results tell us that it may not be that they are round (in the cylinder's case), or smaller (in the lactation case), but rather that those two types of feed drops attach to the feed line such that the volume of feed doesn't change as much when they are at different angles to the feed line,” Tokach observes.

In the end, using the proper type of feed drop will help maximize performance by more appropriately feeding sows housed in individual stalls, he adds.

The final research report on feed drops will be presented at the annual KSU Swine Day, Nov. 16 in Manhattan, KS.

Tokach says future research will assess whether the bulk density of sow diets has any influence on the flowability and accuracy of feed delivery systems.