Refinement of porcine studies is achieved by introducing a standardized checklist and positive reinforcement training using a clicker. This work supports the collection of samples and the conduct of daily chores related to the animals.
This video will introduce the protocol used to transition pigs from primarily conventional farming to research pigs, using the combination of treats, socialization, and positive reinforcement training. As the pigs arrive they are washed and sorted into groups according to the projects they are to be enrolled in. On the arrival day the pigs are left to settle, and the staff limits moving about in the staples.
On the day following arrival the protocol begins. The pig is in its home pen during the transition phase as this is what the pig is familiar with, and therefore gives the best basis of progression when the goal is to make the pig calm in the presence of the caretaker. The first step is introducing treats.
Farmed pigs have never had any other food types than their pig feed so they need to be taught what a treat is. We use apple pieces as a standard type of treat. The first step is to simply toss pieces of apple into the pen and let the pig find it.
In the beginning the pigs may pay no notice to the apples, but usually within a day or two they understand that a piece of apple is nice, and something to look forward to. In the protocol a plus is given when the pig eats pieces of apple within two minutes, and a minus is given if the pig has not found the apples, or won't eat it during those two minutes. The caretaker is positioned just outside the pen to watch the pig, and also to get the pig used to the close presence of the caretaker.
From day three the caretaker enters the pen during feeding. The idea behind this is to take advantage of the pig strong motivation to eat, and combine that with the close presence of the caretaker. The caretaker intercept pen, pours the feed into the trough, and then sits down next to the pig.
If the pig comes to eat the feed the caretaker stays. If the pig refuses to eat while the caretaker sits next to the trough, the caretaker stays for two minutes, and then leaves the pen. When the pig accepts the close presence of the caretaker during feeding the caretaker slowly extends an arm to touch the pigs back.
If the pig backs away from the touch a minus is recorded in the protocol. If the pig accepts the touch a plus is recorded. Once touching is accepted it is slowly increased.
Both in the area touched, and the speed of the movements. Touching of the head, and ears, and hind, and tail, is useful for most projects, so they are scored in the protocol. From the sitting position the hand is moved from the back to the head of the pig, and then moved around to also touch the ears.
When this is tolerated more manipulation of the ears is the next step. When the pig accepts being touched on the head, and having its ears touched and manipulated, a plus is noted in the protocol until then a minus is recorded. Touching the hind and tail is performed by moving the hand backwards on the pig.
In this step the caretaker also rises slowly to be able to move around the pig for better positioning. Standing up and bending towards the pig is more frightening to the pig, so all the movements should be performed slowly. When the pig accepts being touched on the hind, and having the tail touched, and manipulated during a two minute session, a plus is recorded in the protocol.
If during two minutes the pig does not accept this a minus is recorded. In addition to entering the pen twice daily during feeding, the caretaker also enters the pen during the day to further accelerate the bonding process between caretaker and pig. During these sessions the pigs are offered treats by hand.
The caretaker sits just inside the pen, and offers a piece of apple to the pig with an outstretched arm. If the pig eats the apple during the two minute timeframe a plus is recorded in the checklist. If it does not eat the apple from the hand a minus is recorded.
The final step in the transition phase is for the pig to accept being touched by one caretaker while a second caretaker gives the pig treats. This is harder for the pig to accept as it is more aware of its surroundings, and two people are now in close proximity. On completion of the transition phase the pigs will allow collection of basic outcome measures like taking a temperature, manipulating the ears to collect a blood sample, or attaching a bag to collect a urine sample.
Following the completion of the transition phase the pigs are ready to start positive reinforcement training. A clicker is used to signal the coming reward. The use of a clicker compared to a voice signal enables different caretakers to train the same animals.
When the clicker training is initiated the pigs are taken outside their home pen as more space is needed to have the pig move freely about. The free space between rows of pens, or designated room can be used. Shortly after the introduction of the clicker a target stick is introduced.
A target stick is simply a stick with a mark area at one end. We have made one ourselves using a bamboo stick, and adhesive tape. That makes it easy to change the tape as it becomes dirty from contact with the snouts of the pigs.
The pig is allowed to roam about but eventually it will make contact with the caretaker, and the caretaker clicks, and gives the pig a reward in one motion. Multiple clicks are in quick succession. Every click is followed by a reward.
The pig needs to understand that when it hears a click a reward will follow immediately. A few sessions should be used to make sure that the pig understands that a click means a treat, as it is important to be able to give the signal to the pig quickly to be able to reward a specific behavior. When the link between the click and the reward is well understood by the pig, the target stick can be introduced.
The target end is held in front of the pig, and at some point the pig will touch it out of curiosity. At the very second the snout touches the target click and reward. The target is positioned again, and the task is repeated a number of times.
Then gradually the target is moved farther away from the pig to make the pig move to touch it. Within a few sessions the pig will have learned to move around following the target stick. In the beginning the pig will break contact from the target if distracted by new objects, other pigs, or sounds.
But with consistent training the pig will be able to follow the target stick closely even when disturbances occur. When the pig can follow the target stick the stick can be used to move the pig around the facility. At our department it's used to guide the pigs into transport crates, or to move the pigs to our floor scale, and back to their home pen.
In conclusion, the implementation of a structured transition phase has highlighted how fast and smoothly the pigs can adjust to the research facility, and that they are notably less stressed when they enter experiments. Reduction of the pig stress level is a key part of our 3R strategy to improve animal welfare and science. The dedication of our caretakers has increased as well, and this contributes to the department's culture of care, and the collaboration between scientists and caretakers.
