Human error is one of the major causes for out-of-feed events in grow-finish facilities.

A majority of today’s grow-finish facilities have bulk bins and automated feed delivery systems. In theory, these bins and delivery systems assure an uninterrupted flow of feed to the feeder. In practice, grow-finish pigs have varying disruptions in feed availability, some of which may have serious consequences.

Three causes
According to swine production specialists, there can be several causes of out-of-feed events in a swine production system, but in grow-finish facilities they are usually from the following three  major causes.

1. Human errors

These are generally associated with empty bins. This cause occurs when feed is not ordered, prepared and delivered in a timely manner. While preventable, this cause of out-of-feed events occurs more often than producers admit.

It is most likely that this cause has increased as more percentage of feed processing is done by commercial mills, rather than on the farm. In the past, when most feed was processed on the farm, a problem with an empty feeder or empty bin was relatively easy to solve. The producer immediately processed enough feed to fill the bin and/or feeder.

With commercial feed preparation, however, the process becomes more complicated. For example, there may be minimum delivery requirements, such as 6- or 8-ton loads,  that if not met carry additional fees or penalties. Scheduling of transport vehicles and scheduling of processing becomes an issue. Instead of a producer making an independent decision that feed processing is a high priority due to an empty (or near empty) bin, a central mill may require a 24- or even 48-hour notice.


A second major cause of out-of-feed events in grow-finish facilities is feed bridging of ground feed in bulk bins.

Even if a mill accepts same-day orders, an order placed at 7 a.m. (when the empty bin is discovered), may not be delivered until mid-afternoon due to orders already received or previously scheduled. This means producers and production managers must estimate bin inventories and anticipate feed disappearance. Field experience suggests there is a wide variation in the ability of producers/managers to accomplish this vital task.

In one instance, a local feed mill charged a fee for all emergency feed orders (those without at least 24-hour advanced notice). The contract growers were responsible for placing feed delivery orders, based on their expectations of when the bulk bin would accept a delivery unit (6- or 8-ton load). The pig owner noted an increase in fees due to late orders which suggested that the contract growers weren’t monitoring bin inventories close enough to be able to anticipate empty bins more than 24 hours in advance.

To solve this problem, the pig owner began assessing the fees back to the contract growers since they were the source of the fees. In turn, there was a dramatic decrease in emergency feed orders and associated fees. However, it is probably safe to assume that the contract growers didn’t suddenly improve their ability to anticipate feed needs. Most likely, pigs were now out of feed for longer periods of time than before.

Even the addition of a second bulk bin doesn’t always reduce this source of out-of-feed events. In theory, one of the two bins is always full of feed. When one bin runs empty, the producer only has to close the delivery device on one bin and open up the other bin to restore feed access and place an order to refill the empty bin. There are many anecdotal reports from production system field supervisors of producers who by-pass this system by keeping both bins open since it is easy. Now, the two bulk bins are in reality one bin, with no reserve supply.


Equipment malfunction is another major cause of out-of-feed events. This cause occurs more frequently as gow-finish facilities get older.

Several companies offer bin monitoring equipment, but there is an added expense to this equipment, and until data is available to put a dollar value on the impact of out-of-feed events, producers are reluctant to invest in this equipment.

2. Feed bridging

A second cause of out-of-feed events is bridging of ground feed in bulk bins. Feed is in the bin, but because of issues associated with flowability, it does not flow out of the bin into the feed delivery line. Producers often refer to this as “rat-holing” of feed in the bin.

Issues with bridging are generally limited to systems that use meal diets. Recent reports from Kansas State University suggest that as particle size decreases and the amount of fat added increases in corn-based diets, the angle of repose (an estimate of likelihood of bridging) increases.

In the past 10 years, there has been a marked reduction in the average particle size for swine diets, driven by data, which suggests a 1 percent to 1.5 percent improvement in feed conversion efficiency for each 100-micron reduction in particle size from 1,000 to 500 microns. The current University of Nebraska recommendation is to process complete diets to an average particle size of 650 to 750 microns for all grains except wheat. The unanswered question –which is worse, a larger particle size that results in less bridging but a poorer feed conversion or an increase in out-of-feed events due to bridging with a smaller particle size?

Similar to bin level monitoring, there are several companies selling devices that prevent or reduce the incidence of bridging in bulk bins. As with bin level monitoring, there is a cost associated with these devices and out-of-feed events due to bridging hasn’t been thought of as a serious enough problem to warrant investment in these devices on most production facilities.

3. Equipment malfunction

The final cause of out-of-feed events is equipment malfunction. This cause generally increases as facilities age. Some producers may have a larger incidence of this than others due to the level of preventive repair and maintenance.

The incidence of out-of-feed events increases as facilities age, due to both equipment malfunctions and general producer apathy.

To understand apathy, consider what happens in a new swine facility the first time an out-of-feed event occurs. In most cases, the producer panics since their assumption was that the facility was built to provide for the pig’s every need, and an out-of-feed event will have production consequences.

As facilities age and producers experience a variety of out-of-feed events, a general apathy often sets in. Producers with a fixed payment production contract often ask what are/were the consequences to me as a grower from the out-of-feed event? Did the pigs become ill on the day they were out of feed? Did my payment change as a consequence of out-of-feed events? Did the pig owner notify me of a concern because of an out-of-feed event that they didn’t even know about?

Editor’s note: Information in this article has been excerpted and edited from a presentation at last summer’s University of Nebraska George A. Young Swine Conference in South Sioux City, Neb. Mike Brumm, PhD, University of Nebraska Extension swine specialist presented the information at the conference. The information is based on work that he and other animal scientists, including Brian Richert, Purdue University Extension swine specialist and Jeremy Marchant-Forde and Ruth Marchant-Forde, research associates with the USDA-ARS Livestock Behavior Unit at Purdue University, have done.

Some consequences of out-of-feed events

Based on scientific research and anecdotal reports, some consequences of out-of-feed events can include:

  • An increase in redirected behavior, such as pen-mate manipulation and an overall increase in activity.
  • Skin lesions and within-pen variation in weight gain can become increasingly apparent, indicating that relative social rank becomes a factor in gaining access to feed.
  • Considerable anecdotal evidence suggests that when pigs are given access to feed following a period of deprivation, large amounts of fighting and aggressive behaviors occur and it is likely that this will adversely affect the welfare of all pigs within that pen.
  • Difficulties in gaining access to feeders appear to influence the number of feeding events and the length of these feeding events. It is possible that periods of feed unavailability will cause a disruption in the circadian pattern of many behaviors within the pen.
  • There is evidence that variation in weight gain increases when signals of feed availability are unreliable versus reliable.
  • A potential welfare issue with periods of feed restriction is gastric ulceration. Gastric ulceration is a common condition in modern pig production, with slaughter plant reports varying from 30 percent to 90 percent of all pigs in the U.S. having some amount of stomach ulceration. Short-term feed deprivation has been clearly shown to create ulcers in growing pigs. Periodic feed interruptions will likely create a similar effect in ad libitum fed pigs.
  • Recent research suggests that interruptions of feeding, such as occur with out-of-feed events, can be an inciting factor for hemorrhagic bowel syndrome. Hemorrhagic bowel syndrome is a health concern because as much as 50 percent of all grow-finish deaths on some farms are attributed to this cause, and sporadic outbreaks may result in upward of 10 percent to 20 percent mortality in severe instances.
  • Another research project  suggests that if pigs miss one or more meals in a 24-hour period, they do not compensate for this missed feed intake by over-consumption when feed does become available. In this study, the  estimate of the economic consequence of an out-of-feed event is based on when the feed delivery failure occurs. If it is sometime during the night and feed is rapidly made available first thing in the morning, there is little consequence. If feed delivery stopped immediately after the previous morning’s observations of pig health and other things, and feed isn’t available until 4 p.m. on the following day, this is more than 24 hours of feed withdrawal (depending on the amount of feed in the feed hopper). This is a enough time to likely result in catabolism of body stores.
  • Research suggests that pigs transported to slaughter plants and given water but no feed access during lairage have a relatively rapid loss of both live and carcass weight beginning approximately 18 hours after the last meal. The rate of live weight loss was approximately 0.21 percent/hour and the loss in carcass weight was 0.13 percent/hour of fast. The difference in rate of weight loss is presumably due to loss of intestinal fill, a loss that would be immediately restored with feed availability.
  • Repeated out-of-feed events may impact carcass composition. Researchers have reported  that pigs fed ad libitum every other day with a one-day fasting period had a reduction in daily gain with minimal impact on feed conversion efficiency. However, carcass-dressing percentage was reduced, in part because a higher percentage of weight at slaughter was visceral mass. It has also been reported that there can be an increase in backfat depth for pigs fed every other day versus once or twice daily.
  • Based on scientific observation, in all likelihood, any tissue gain that is lost because of an out-of-feed event is not compensated for in subsequent meals. In terms of economic impact,  a 20 hour out-of-feed event can be thought of as the equivalent to one day longer to slaughter, which would be a severe cost in systems of production which have fixed time constraints on production flow.