Breeding Herd Management and Performance in a
Swedish Deep-Bedded Gestation and Group Lactation
Demonstration, Armstrong Farm, Iowa State University

Dennis Kent
Livestock Specialist, ISU Research and Demonstration Farms

Background

The ISU Armstrong Research and Demonstration Farm in Pottawattamie County, Iowa is the site of the demonstration. The Wallace Foundation owns this farm for Rural Research and Development, a non-profit group interested in sustainable agriculture. The farm is in southwest Iowa where summer temperatures and humidity are extreme for Iowa. This report concerns primarily our experience with breeding herd management and performance, although some farrowing and nursery results are given in a footnote.

In Sweden, a variety of naturally ventilated buildings, including old barns, are used for breeding and gestation; thus a hoop structure seemed to be an analogous choice. Ours is 37 feet by 70 feet (Fig. 1), and is marketed by Cover-All,² Clarinda, Iowa. It is oriented north-south and consists of six-foot wooden side walls and an arched tubular frame covered by a polyethylene cover or tarp.

When I began to think about the kinds of features that would be needed in a hoop structure for gestating sows, based on what I'd seen in Sweden in 1994, the most important ones to transfer directly from Swedish experience seemed to be: space per sow in the beds; adequate ventilation to cope with composting beds; individual feeding stalls, one for each sow; ad lib water accessibility; a four-foot wide feeding alley; and fully cemented floor.

Because ours is a research and demonstration facility, there is extra space and construction devoted to non-production activities and we have some extra equipment. A wooden observation deck was built along the outside of the north end of the structure to accommodate visitors. Because the cost per sow space of our facility is high if you don't subtract these extras, the cost figures from Dan and Colin Wilson's operation are likely to be better indicators than ours of building costs for producers wanting to build a hoop gestation structure with Swedish design features.

The feeding stalls and waterers were placed on a raised concrete platform. For feeding stalls, we were helped by Tom Van Milligen, a Nova Scotia producer who adopted the Swedish deep-bedded group-nursing model in 1990. At that time no one in North America was manufacturing these stalls. Van Milligen spent a considerable amount of time trying to convince manufacturers to build them for him. He finally managed to interest BSM² in Ontario and they were our suppliers also, via an Iowa distributor.

I can't stress enough the importance of having an individual feeding stall for each sow in the gestating group for the purposes of management, feeding efficiency, and labor savings. Feeding stalls offer the advantages of individual gestation crates: individual feeding, eliminating competition at feeding, control of the sow for vaccinations and pregnancy checking, and easy sorting of sows. But they also allow for freedom for the sows which I have found to improve the attitude of the animals very much, making them more relaxed and easy to be around. In addition, continuous free access to the stalls allows sows to get away from the bed when they want to, which can be often in summer.

Drippers were installed over the feeding stalls to aid in cooling the sows on hot days. All floor areas of the hoop structure are concrete. Access for adding bedding is from the south end. The north end is closed in winter with a fabric curtain. The south end was partially closed in winter.

We use large round bales of cornstalks for bedding in the hoop. Seventy-five bales were used in 1997. We would have used slightly more but had to stretch our supply when we got close to running out and couldn't get in the field because of rain. Swedish guidelines for bedded space of 27 square feet per gestating sow were followed. We used about 20 tons of sow feed in gestation for between 25 and 30 sows.

We began with Yorkshire x Landrace F1 gilts and two Hampshire boars who arrived in the gestation unit during March 1996. Breeding began on May 14, 1996, and 14 gilts were bred using natural service (hand mating) and artificial insemination (AI). We chose these genetics because most Swedish farms use Hampshire boars on Yorkshire x Landrace sows. The second group of gilts (13 head) arrived in June 1996. Fifteen gilts were bred beginning August 1, 1996, using natural service and AI. The first group of gilts started farrowing on September 5, 1996. The second group began farrowing on November 24, 1996. We farrow every 11 weeks because on this demonstration farm we have only one deep-bedded group farrowing room modeled after a single room in a Swedish group lactation system. We now have 25 sows in the two groups (December 1997) and are in the fourth farrowing for the first group.

The bedded area in the hoop is divided into a part for gestation and a part across from the boars where the sows are bred. We have the boars housed on the other side of the feeding alley from the sows. The procedure for breeding sows is as follows: All sows are weaned on a Thursday. Sows are removed from the group lactation barn and taken to the hoop. Heat checking begins on Monday. We lock the sows into the feeding stalls while they are eating. Each female to be bred is taken individually out the front gate of her stall to the boar pen. When the sow stands for the boar, she is removed to a separate pen and artificially inseminated. Each sow receives three services, 84% of which are AI.

We use no medication in the gestation or lactation diets. All breeding stock is vaccinated with FarrowSure B and Litterguard LTC; Ivomec injectable is also used.

The hoop building was cleaned out five times in 1997 and on average is cleaned about four to five times per year depending on bedding quality and stocking density. At cleaning time the manure/bedding mixture is either directly spread on fields or stored. Because this is a solid manure handling system, storage requirements are minimal. Composting results in volume reduction and nutrient stabilization prior to field application. Bedding from gestating sows in hoops tends to be much drier than that from finishing pigs. The lower moisture content of the bedding tends to limit the extent of composting unless additional manure or water is added to the piles. We add some water.

The high degree of variability in the bedded pack makes it difficult to predict manure nutrient contributions to crop fertilization needs. Mixing the material after it comes out of the hoop to achieve a higher degree of uniformity would improve this situation. Such mixing currently occurs to some degree when we remove the bedded pack from the buildings and store it. Additional mixing, such as would occur during turned windrow composting, may offer additional benefit. So far we have not made this extra effort but trials to examine the effect of storage, mixing, and composting on manure nutrient levels and uniformity are planned for the coming year.

The breeding/gestation unit has worked well. The cornstalk bales for bedding are easy to use and are unraveled by the sows into absorbent bedding. Preferred dunging areas are quickly established by the animals, and additional bedding is normally added in those locations to absorb excess moisture. The nutrients and moisture contributed by the manure help initiate incidental composting, which generates some heat in the bedded pack. We have not actually measured the temperature of the pack. During the summers the hoop also performed well. Ventilation and sow comfort were adequate at all times. The drippers were used occasionally. Sows were generally quiet and content. No stereotypic behavior was observed, i.e. unnatural sow behaviors that result from environmental stress.

As of December 1997, the sows in this deep bedded system have a 97% returns to heat rate, a conception rate of 97%, and farrowing rate of 96% over eight breeding periods (two groups, four parities each). Litters born per sow per year are between 2.45 and 2.53, with a five week weaning. These results can be attributed to the more natural conditions in the farrowing house: ad lib feed and water, exercise including a straw bed to root in, and the freedom of the sows to initiate the weaning themselves. These features leave the sows in good physical and mental condition. It can also be attributed to the breeding management in the Swedish system -- that is, simultaneous weaning of the sows at five weeks to return to the hoop which causes a synchronous estrus within four or five days, and the ease with which group housing stimulates estrus. Breeding management is important because we also use a Swedish-design farrowing house and group lactation method known as the Thorstensson system. A short (< 7 days) interval between first and last born litters in a farrowing is critical for group lactation to succeed.

Because of the large space allowance, the lack of competition for feed, and the fresh bedding to keep the sows occupied, they are very relaxed and friendly -- like big pets. Sow condition is excellent and this has helped with farrowing. I wasn't attending as much during farrowing as I should have been because I also am in charge of swine operations at the Southwest Swine Research and Demonstration Farm several miles away, but the ease of farrowing is shown by the very low stillborn rates. Out of 81 litters (7 farrowings) born prior to December 1997, 29 pigs have been stillborn, averaging about 0.37 stillborns per litter or 3.3% of total fetuses. Over the first four farrowings for which we have actually completed an analysis, birthweights improved from an average 3.5 to 4.4 pounds per pig. Large litters of heavy pigs born in a short time reflect an excellent breeding and gestation environment in the hoop structure.3

We have held two field days at Armstrong Farm. The first, on September 12, 1996, was attended by approximately 150 persons. The things most visitors notice are the generally pleasant odor from the beds, the activity levels of the sows who spend a good deal of the time rooting in the bedding and carrying stover from place to place, and the peaceful relationships among the sows. For us who are working with the system, the most noticeable disadvantages are time and labor involved with cleaning and hauling of bedding and having to be timely in getting bedding baled in fall. It is a narrow window—we hire a custom baler who also farms and has his own fall harvesting. The advantages are low odor, excellent sow behavior and performance, and pleasant working conditions.

More producers are starting to look at loose-housing and solid bedding systems for their gestating sows. I think the Swedish layouts and features for deep-bedded loose-housing systems hold a lot of promise for Midwestern producers although they demand a different kind of management from intensive confinement, and even from pasture or non-confinement systems. This management style must be tuned to the sows' natural behaviors and how these behaviors play out in a loose but still confined type of housing system.

Figure 1. Plan view, Swedish-style loose-housing in a hoop for the breeding herd, I.S.U. Armstrong Research and Demonstration Farm, Lewis, Iowa.

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