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Understanding the options for group sow housing

Second of two articles on group sow housing

There are a number of group sow-housing systems that can be used in converted buildings or new barns. Each of them has particular features and limitations that need to be understood in order to make an informed decision about which system to choose. While there are certainly differences in cost, it is most important to select a system that meets a producer’s individual objectives without compromising performance.

Electronic sow feeding

The use of individual electronic sow identification allows accurate feeding in ESF systems and permits feed levels to be adjusted automatically, according to stage of pregnancy. This gives very accurate control of sow body condition and is the major advantage of the system. Depending on design, feeders will each handle 45-60 sows. The number of sows bred each week will determine whether “static” or “dynamic” sow groups are used. With static groups sows are only mixed at entry to the pen, whereas dynamic groups have new sows added either each week or sometimes every two to three weeks. The use of static groups simplifies both housing design and management procedures.

Dynamic groups, typically of 100-250 sows, give great flexibility in terms of the number of sows bred each week and do not require sows to be remixed at any stage. Their main drawback is that management is more difficult because the group contains sows at different stages of pregnancy. Keen observation skills and a clear identification and marking system are therefore essential.

Automatic separation systems may be used to isolate sows from the group for heat checking, pregnancy testing, vaccination or transfer to the farrowing barn. Also, sows in large groups are extremely docile, making routine tasks easy.

Unlike other systems, ESF requires sows and gilts to be trained to use the feeder. Gilts are quick to learn and rarely need retraining, but where existing herds are converted to ESF, a small proportion of older sows may fail to learn and have to be culled. Training requires a significant time input when a system is first installed.

Electronic feeding equipment is now extremely reliable but when a breakdown does occur, it can result in aggression. Consequently it is important to deal with a supplier that has a good knowledge of the equipment, carries a full range of spare parts and can provide a 24-hour maximum response time.

Free-access stalls

This system is widely used in Denmark, with both bedded or slatted floors. As its name suggests, sows are able to move in and out of a feeding/lying stall with a hinged rear gate that closes to protect them from other sows. The animals are individually fed, either automatically or by hand, however, sows do not always use the same stall, so manual topping up of feed is necessary where feed dispensers are used. Group size is typically six to 20, although could be larger depending on pen layout. The system’s biggest advantage is its simplicity, although it is relatively expensive.

Trickle feeding

This feeding method uses the principle of “biological fixation,” whereby if feed is delivered to the sow at a rate less than she is capable of consuming, she will remain in her place and not attempt to steal another sow’s feed. In practice this involves using short (head and shoulders) feeding stalls and delivering feed into an individual trough or onto the floor at a rate of about 150-200 grams/minute. Although sows sometimes move from one stall to another, this provides no advantage and consequently the level of aggression is minimal.

Trickle feeding is usually used in small groups of six to 12 sows, making it most suitable for units of 200-600 sows. Slatted floors and unbedded lying areas may both be used successfully. The system provides simultaneous feeding allowing inspection of all sows to be carried out at feeding time and sows do not require training to use the system. Fixed groups based on service date simplify routine management tasks as all sows in the group are at the same stage of pregnancy.

Automated floor feeding

This simple system uses feed dispensers above the lying area to drop feed onto the floor and group size is typically six to 25 sows per pen. It is suitable only for fixed groups because experience with dynamic groups has shown unacceptable aggression.

Control of individual feed intake is poor because the dominant sows are able to eat more and this results in variable body condition. The problem can be reduced by splitting each week’s sows into at least two groups and penning gilts separately. However, even where this is done, some variation in condition will occur.

Although the system has a comparatively low capital cost, it has a number of disadvantages. Some aggression inevitably occurs during feeding, which can result in physical damage to less-dominant sows. It is also necessary to give more feed overall to maintain adequate condition in the thinnest sows and the added cost involved justifies the use of a more sophisticated system that provides more accurate control of feed intake.

There are a number of other group-housing options available, including liquid feeding in troughs and a range of proprietary feeding systems that are currently available in Europe.

The design of group systems is critical to success because deficiencies in the layout can lead to serious aggression. Therefore it is essential to get good advice on design to avoid problems. Group systems, in particular dynamic groups on ESF, require a higher level of management ability and a slightly higher time input than sow stalls. As with any new system, producers and their staff must be committed to making it work.

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