Bradley Wolter(l) and Dr. Mike Ellis

Does it make sense to overfill wean-to-finish pens early in the feeding period? The obvious benefits of extra throughput and lower facility cost are enticing. The practice may also help smooth out pig flow and lower nursery phase overhead, according to experienced advisors like Dr. Tim Loula and his colleagues at the Swine Vet Center in St. Peter, MN. But double-filling is not without challenges because more labor is needed and it can be difficult to spot problems and treat sick animals. Furthermore, two recent research studies point out that performance may not be equal between double-filled and single-filled barns.

Research conducted in 2000 at the University of Nebraska demonstrated that double-stocked pigs in wean-to-finish pens (3.75 sq. ft./pig (.325 sq. m/pig) were roughly four pounds lighter at eight weeks than pigs fed in single-stocked (7.5 sq. ft./pig (.650 sq. m/pig) wean-to-finish pens. See Chart A.

Recent research at the University of Illinois also found a significant performance difference. This study demonstrated that double-filled pigs weighed about 6.5 pounds (2.9 kg) less at ten weeks and had lower average daily gains, than their single-filled counterparts. See Charts B and C.

The Nebraska and the Illinois studies suggest there are no differences in performance between the groups after half the pigs are moved. In the Illinois study, pigs that were double-stocked arrived at a market weight of 250 pounds (114 kg) about two days later (including the half that stayed in the same pen and the half that moved) than the single-stocked pigs. "They didn't grow any faster (after being moved)," says Dr. Mike Ellis, the lead researcher in the project. "The double-stocked pigs improved slightly in feed efficiency," says Dr. Ellis, but adds further research will be needed to determine whether the feed efficiency change is due to chance or a real effect. See Chart D.

Consulting veterinarian Dr. Joe Connor, who has been advising producers on managing wean-to-finish systems since the mid-1990s, says he recommends producers stick with single-filling unless traditional finishers are available for placing pigs into after the first eight weeks. Dr. Connor, of the Carthage (IL) Veterinary Service, Ltd., indicates that death loss during the first eight weeks past entry in double-filled, wean-to-finish buildings is twice what it is in single-filled buildings.

As a compromise, Dr. Connor often advises overfilling at 150 percent capacity. "If producers are normally populating at a rate of 25 pigs per pen, increase to 37 pigs," says Dr. Connor. He recommends starting pigs by feeding them multiple times per day on feed mats as well as in the feeder. Increase the warm zone by placing heat lamps higher than usual or installing additional lamps. Dr. Connor says producers should expect a reduction in performance when pigs reach the size that space is limiting.

Swine veterinary consultants Drs. Tim Loula, Paul Yeske and Ross Kiehne at the Swine Vet Center have many clients who double-fill into wean-to-finish facilities. The consultants say the first ten days following entry are critical for getting pigs started in over-filled barns. They suggest using two mats or one oversized mat for hand-feeding.

Perhaps the greatest benefit of double-filling wean-to-finish barns is that it offers producers more options for pig flow. The Swine Vet Center consultants say producers can play a bit with timing of when to move pigs out of the overfilled pens, which can help in tight flow patterns. In addition, pens can be filled at various capacities (any increment between 100 and 200 percent) to match pig source inventories.

But there may be some flow problems that are exacerbated by overfilling. "It may take longer to fill the site, or it may require more sources to fill the site quickly," offers Drs. Loula, Yeske and Kiehne. Another worry is that some of the advantage of a wean-to-finish system gets diminished when some pigs are moved during the feeding period. They say groups and socialization are usually disrupted because of the necessary regrouping to even out pig size within the pens.

Dekalb, IL, producer Bob Johnson has found a solution to concerns about disrupting group integrity. Two years ago he and his partner, Dr. Steve Pate, designed a wean-to-finish barn for double-filling without the need for mixing up or dividing groups. The design created rooms that hold either 500 weaned pigs or 250 finisher pigs. When the rooms are filled, weaned pigs are sorted by sex into alternate pens. After 8 to 12 weeks, pigs in every other pen are moved (all the gilts or all the barrows) into another room. "The remaining groups are allowed access to neighboring pens by opening a divider gate," says Bob. "They have double the space with no mixing of groups." The system has worked well, according to Johnson, who says he and Pate are convinced that mixing of groups is something to be avoided to maintain health and so not to disturb the social environment. He says the divider gates also help when working with pigs after they are single-stocked.

Another recent Illinois study looked at whether adding feeder space in double-stocked pens increases pig performance. Dr. Ellis' graduate student research assistant, Bradley Wolter, presented those findings along with the stocking rate findings at this past summer's annual meeting of the American Society of Animal Scientists. The researchers set up the trial with two treatment groups of double-stocked pigs. The "control" group of pigs had one six-hole Farmweld dry feeder that provided .79 inches (2 cm) trough space/pig and the "double" group had two six-hole Farmweld feeders or 1.57 inches (4 cm) trough space/pig. Group size for all pens was 108 pigs with a space allotment of 3.75 sq. feet (.30 sq. m) /pig.

The Illinois researchers found feeder space did impact performance of double-filled pigs during the first eight weeks after weaning. While limited feeder space did not lower performance during the first six weeks of the trial, it did during weeks seven and eight. During those weeks, pigs that had increased feeder space had a five percent increase in growth. See Chart E.

The practice of double-stocking wean-to-finish barns is something people will continue to watch closely. Thanks to researchers such as those at the University of Illinois and the University of Nebraska, plus the experience of consultants such as veterinarians and others, producers will be better able to determine if the practice benefits their particular system.

CHART A
IMPACT OF WEAN-TO-FINISH REGIMEN ON PIG PERFORMANCE

CHART B
EFFECT OF STOCKING RATE ON BODYWEIGHT
AT START OF TEST AND END OF 10 WEEKS

CHART C
EFFECT OF STOCKING RATE ON PIG PERFORMANCE
FROM START OF TEST TO END OF 10 WEEKS

CHART D
EFFECT OF STOCKING RATE ON PIG PERFORMANCE
FROM WEEK 11 TO END OF TEST

CHART E
EFFECT OF FEEDER TROUGH SPACE ON PIG PERFORMANCE