Free-Access ESF feeders are a relatively recent feeding system that was developed by producers in Quebec. Since their development they have become a popular alternative for feeding sows. As the name suggests, the feeder combines the features of both free-access stalls and ESF systems. The feeder provides individual feeding to sows, using an RFID ear tag and offers programmable feed curves, similar to ESF systems, but at a reduced sow-to-feeder ratio compared to ESF. The recommended sow to feeder ratio is 20:1, with typical group sizes of 40 to 60 sows. This results in less competition at the feeder entrance and more social facilitation of feeding behaviour as multiple sows can feed side-by-side in the feeder stations. Like free-access stalls, sows are fed in a self-closing stall which protects them during feeding, and they must back out of the stall to exit. Because of the lower sow numbers fed, there is little aggression observed at the feeder entrance- sows enter the feed stations and feed calmly, with minimal displacements or aggressive interactions at the feeder entrance.
Compared to free-access stalls, the free-access ESF feeder has the advantage of providing individual feeding, while requiring less pen space and penning because each feed stall is shared. 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.
Based on these characteristics, the system combines the advantages of existing non-competitive feeding systems, and at a reasonable cost.