Managing TRAINING for your barn.
In many non-competitive feeding systems training is an important step to ensure the transition to group sow housing.
Electronic sow feeders (ESF)
Some training of sows and gilts is required with the ESF system. When transitioning to ESF all animals must be trained, however, once the initial training is complete, only new gilts entering the system will require training. Some sows and gilts may be cautious and reluctant to enter the feeding station if they have not come in contact with it before. A separate training pen should be used to train the sows and gilts on how to access the feeder system .This system of gated areas allows staff to adjust the size of the entrance and exit pens as the day progresses. Some sows or gilts will need encouragement to enter the feeder. This can be done by placing a small amount of feed on the floor at the feeder entrance to encourage the sow or gilt in. Use of low stress animal handling techniques is also an option to get the sow or gilt into the feeder.
Training pens should consist of groups of 30 – 40 sows or gilts, and training should ideally occur before breeding when any missed feeds will not affect production. Early in the training period, the gate to the ESF can be tied open, and feeders should be well illuminated with overhead lighting to encourage exploratory behaviour of the sows.
Some feeders have a manual training button that, when pressed, will dispense feed when the sow enters, providing an immediate reward for entering the feeder. As sows become accustomed to the ESF, less interference by staff will be necessary and the gate to the feeder can be gradually closed. The training period will take 7 to 14 days to complete. A training pen can also be set up using gates similar to the ESF, but without the ESF unit, in order to facilitate training without the added cost.
Stockpersons with excellent animal handling skills and patience should be responsible for ESF training. It is vital that sows or gilts do not have a negative experience when learning to use the feeder as they can become reluctant to enter. After the whole barn has been trained, the training area will be used only for gilt training. This should also take place prior to breeding. If carried out correctly, gilts will become used to the feeder and to handling as the training progresses.
Free access electronic sow feeders (ESF)
The stall is also very easy for sows to use, with a simple gating system that requires minimal supervision or training. Most sows learning the system with no manual training. Gilts should be introduced to the system a week before mature sows, or can be trained in a separate pen with additional space and reduced sow numbers. Gilts and sows require some training to learn how to use the feeding stalls. Training areas can be used prior to breeding and should provide 1 feeder per 7 to 10 animals. Sows will tend to learn the system faster than gilts; slower learners will learn by observing faster.
Stockpersons that are conducting the training need to follow a carefully structured program and be patient with the gilts to avoid creating any negative association with the feeders. Special attention should be paid to ensuring the gilts learn how to trigger the mechanisms that allow them to feed and to exit the stall.
In dynamic groups, small groups of sows are added to a larger existing group periodically throughout gestation, and groups are also removed periodically as sows move to farrowing. Each time a new group is added a new bout of aggression will occur. However, with large dynamic groups it has been shown that sows adopt a more tolerant and passive response to unfamiliar animals. A pen layout that includes adequate space, and the addition of dividing walls for escape and to hide behind, helps to reduce the aggression.
Group size
Group size can also influence sow aggression within the group. Smaller groups of sows (8-10) will form a social structure with stable, linear hierarchies. Larger groups of sows (≥40 animals) develop a different social structure in which there is a greater tolerance and less aggression. It is believed that the cost of establishing dominance in a larger group is greater, and so animals learn to adopt a more tolerant approach rather than trying to dominate. Instead, sows in large groups will form smaller sub-groups, or cliques of sows that lie together.
With dynamic grouping, maintaining large groups is one way to help control aggression. In the dynamic setting, the addition of a smaller group of sows to the larger group lends itself to the natural formation of sub-groups of sows. To help reduce the stress to animals added to a dynamic group, it is recommended that animals added to a new group should make up at least 10% of the total group size.
Many producers use an introduction pen that allows incoming sows to be penned together and become familiar with one-another before joining the larger group. These sows typically remain together as a sub-group once they join the larger group. A specially designed mixing pen can also offer better conditions to minimize aggression and stress, including features such as extra space per sow, better flooring to help prevent injuries and provision of enrichment or bedding.
Grouping by size
Grouping sows by size (and/or parity) can help to even out competition within the group, helping in particular the smaller, younger parity sows to do better by not having to compete against larger, older sows. Grouping by size is especially important in competitive feeding systems where smaller sows will be at a distinct disadvantage when competing for feed.
Research has also shown advantages to grouping sows by parity in non-competitive feeding systems. Grouping sows by parity was found to be advantageous for parity 1 sows managed in a static ESF system. Younger sows in the study were able to maintain backfat when housed together, but lost backfat during gestation when kept in mixed parity groups. It is likely that maintaining the sows in uniform parity groupings reduces competition for entry to the ESF feeder, helping to ensure all sows receive their daily feed allowance. Research indicates that grouping sows by parity can also benefit young sows fed in free-access stalls. When housed in mixed parity groups, younger sows spent the majority of time in the free-access stalls, but when housed with other young animals the sows spent more time out of stalls in the common loafing area.
Why do sows fight when re-grouped?
Our reluctance to keep sows in groups seems somewhat misplaced as in the wild pigs live quite harmoniously in groups of numerous sows and their litters (Gonyou, 2001). The difference between commercial production and living in the wild is that sows in the wild rarely, if ever, incorporate new sows into their group. If any sow attempts to join a group, she will be attacked by the resident sows and forced to leave. That is really what happens when we mix sows in commercial conditions: the resident sows attempt to drive away the intruders. Difficulties arise because the new animals cannot leave (Mendl and Held, 2001). Although we often attribute the aggression of newly mixed pigs to the need to establish their dominance order, that is likely a secondary aspect of the aggression. Subordinate animals cannot just submit and accept a low position in the dominance hierarchy; they must also find a way to be tolerated within the group.
The key to remaining in the group is to stay on the periphery. Moore et al., (1993) and Kraus and Hoy (2011) studied the lying position of sows after new animals were added to an established group. The new animals slept together, apart from the resident animals for several weeks after being introduced. Gradually they were able to integrate into the main group. Once established, the stability of a group of sows is maintained more by avoidance than by aggression (Jensen, 1982). Maintaining separate sleeping areas contributes to this avoidance.
Within a well managed group housing operation, many animals within a group will be familiar with each other from their previous gestation period. Sows are able to remember previous pen-mates even after several weeks of separation during farrowing and nursing (Arey, 1999). Consequently, when sows are grouped for a subsequent gestation period, the group consists of previously acquainted sows (an established group) and a number of new animals. The new animals will generally be gilts or 1st parity animals recently added to the breeding herd. Thus, the challenge often associated with younger animals, being the least able to dominate, is confounded by the fact that they are also new. Younger animals (Strawford et al., 2008) and newly introduced animals (Moore et al., 1993) end up sleeping in the least preferred areas of the pen.
How much do sow fight, and how severe are the injuries?
Re-grouping aggression is described as intense but short-lived. Fighting is greatest during the first three to four hours after mixing, and decreases to very low levels by 3-4 days after re-grouping. Reports differ in how aggression has been defined, but the average number of fights during the initial three hours is generally less than three per animal (Moore et al., 1993, Strawford et al., 2008, Kraus and Hoy, 2011). Extrapolating the data of Kraus and Hoy (2011) we estimate that new sows added to a pre-existing group of familiar animals will fight less than 30 times during the first four days. The length of fights have been found to range from eight to 420 seconds but average at around 70 seconds (Arey, 1999). In the first three hours after mixing, the average time spent fighting by sows was reported to be 68 seconds by Strawford et al., (2008). A very similar value was reported by Moore et al., (1993) for new sows in a group, but new gilts were much lower, and fought for a shorter duration. In general, new sows are involved in more aggression (Kraus and Hoy, 2011), and older animals fight more than younger ones (Moore et al., 1993).
Fighting is sometimes assessed by the degree of injuries received over a period of time. Hodgkiss et al., (1998) reported that only 0.16% of injuries received (when studying sows in an ESF system) were considered severe, and of the severe injuries, half were to the vulva. The vast majority of injuries due to aggression are in the form of surface scratches to the skin, generally on the neck and shoulder. However, the incidence of scratches is greater for younger, smaller animals (Hodgkiss et al., 1998) even though they are involved in less fighting than older sows (Strawford et al., 2008).
It needs to be recognized that most reports on aggression and injuries report average values for either the entire group of animals, or particular sub-groups (such as gilts or newly introduced animals). The extremes in terms of number of fights, time spent fighting and severity of injuries may not be reported. Nevertheless, it can be said that the majority of sows in a group are involved in few fights and for a short period of time after regrouping.
