Providing Meaningful Environmental Enrichment and Measuring Saliva Cortisol in Pigs Housed on Slatted Flooring

This protocol demonstrates how to provide practical meaningful environmental enrichment for pigs which are housed on slatted flooring during the different stages of their lives, and how to collect saliva samples in a non-invasive manner for the measurement of cortisol concentrations, as a biomarker for acute stress.

In this video we will demonstrate how to provide practical meaningful environmental enrichment for pigs which are housed on slatted floor during the different stages of their lives and how to collect saliva samples. The environmental enrichment protocols can be implanted easily in almost any swine farm and potentially can improve animal welfare. The saliva sampling is done noninvasively and can be used for cortisol measurements to assess stress or for the measurement of other biomarkers.

To begin this procedure hang the enrichment materials in the farrowing pen before the sow is moved into it. For each farrowing pen prepare two pieces of jute and two pieces of 100 percent natural uncolored cotton ropes each approximately one meter long. Tie the jute and cotton ropes to the pen's bars from it's middle allowing the two free ends of each piece to be hung towards the floor.

The height of the jute and cotton rope's knots should be just lower than the sow's shoulder while the free ends are just above the floor. After piglets are born hang the jute and cotton ropes so that they are reachable for both the sow and it's piglets in a safe place. Typically, when the materials are reachable for both piglets imitate their dams from a very early age.

Shredded paper can also be provided as additional environmental enrichment for the farrowing sows and piglets by spreading it on the slatted floor. For each pen prepare pieces of 100 percent natural uncolored cotton rope that are one meter long making sure to prepare at least one piece for every ten pigs. Tie the cotton ropes to a chain hung from the ceiling or to a hanging hold.

Position the ropes at the center of the active area of the pen close to the feeder and drinkers and far from the pen's wall to allow 360 degree access. Hang the ropes at the height which allows the pigs to easily reach it with their mouths. Typically, the knot should be lower than the pig's shoulder while the free ends of the ropes should be just above the floor without touching it.

In addition to the cotton ropes provide chewable silicone sticks. The device used contains four chewable sticks which allows at least four pigs to interact with it simultaneously. Hang the chewable device with a chain from the ceiling to allow swinging movement.

Position the device at the center of the active area of the pen making sure that the end of the silicone sticks are at a height 10 to 20 centimeters above the floor. First, provide each pen with a straw placed in a rack. Hang the straw racks at a height which is reachable for all pigs.

Usually just below the shoulder level and attach them to the wall with the easiest access for as many pigs as possible. Make sure the racks are completely filled with straw at the beginning. A small amount of fresh straw can be added every one to three days.

Alternatively, refill the rack when it is empty which typically occurs every seven to ten days. As an alternative to the racks straw can be provided in baskets. Plan saliva sampling for the same time of the day to avoid bias as cortisol secretion changes along the day due to physiologic circadian rhythm or due to feeding.

Sampling is typically easier before feeding preferably before the second feeding of the day. In ad libitum feeding plan for the same time of the day. Prepare one piece of uncolored 100 percent cotton rope for each 12 to 15 pigs.

Tie the rope close to the center of the pen far from the pen's walls. Make sure that the cord used for hanging is not reachable for chewing by the pigs and that the free ends of the cotton ropes do not touch the floor. Then unravel the free end of the rope to increase the available chewable surface.

Leave the rope hanging for 15 to 30 minutes. To extract the saliva from the rope put the free part of the rope into a sterile plastic bag and squeeze it by applying pressure from the outside of the bag from top to bottom until enough liquid accumulates at the bottom of the bag. After this, remove the rope from the bag.

Cut the bottom corner of the bag above a 50 milliliter sterile plastic tube and allow the saliva to drain into the tube. Then seal the tube and mark it with either a permanent marker or a pre prepared sticker. Store the saliva samples in an insulated container with ice packs until delivered to the lab.

In this study piglets were allocated randomly into two treatment groups. One which received environmental enrichment and one which did not. Saliva cortisol samples were successfully collected every two weeks just before the second feeding of the day.

The pigs in the enriched group showed high interest in the saliva collecting cotton ropes from the beginning. However, the non-enriched group saliva volumes are typically lower in the initial collection but seem to be similar between the groups from the second or third collection sessions. Typically, a volume larger than 30 to 40 milliliters is easily extracted from each row.

Cortisol concentrations, as measured by Elisa were overall significantly lower in the enriched pigs as compared to the non-enriched pigs. Pigs can be environmentally enriched at all life stages even on slatted floor using jute, cotton ropes, straw in racks and bite-rite devices. The type of enrichment and the way it is located within the pen are important for it's effectiveness.

Saliva collected noninvasively by cotton ropes as demonstrated in this video can be used for cortisol measurement as well as other biomarkers or even for the screening of pathogens.