Managing young pigs in large group auto-sort (LGAS) systems poses challenges to pigs’ eating behavior. By ensuring that pigs have adequate room to access feeders and managing how they are introduced to the system, pigs can maintain feed intake and readily adjust to this housing system.

Pig behavior was studied in two LGAS systems to determine what adaptations were made at the Prairie Swine Centre Elstow Research Farm and in a commercial grow-finish operation. The Elstow facility housed approximately 250 pigs, with one feeder space per nine pigs. The commercial farm maintained groups of 650 pigs with 60 feeder spaces — a slightly higher feeder-space-to-pig ratio.

At the Elstow research facility, the daily pattern of scale use, the use of individual feeder spaces within the food court, and the eating pattern of individual pigs were studied. Movements through the scale (hits) were studied using automated output from the auto-sort scale. All of the feeder spaces were photographed at five-minute intervals using a time-lapse camera. Ten pigs in each study group were paint-marked.

The study at the commercial farm also used output from the auto-sort scale, and supplemented this with live observations of four rooms of pigs for a 24-hour period. Pigs normally have a daily eating pattern with most of the eating taking place during the day.

Figure 1 shows the distribution of weights recorded by the auto-sort scale during a period when pigs averaged approximately 98 lb. The second cluster to the right represents times when two pigs were in the scale.

Analyses of the photos of the feeder spaces showed a clear diurnal (daily) pattern, with an eight-fold increase in eating behavior during the daytime, compared to the low activity pattern at midnight.

Pigs in small groups typically have 10-15 well-defined “meals” in a day. Pigs in the LGAS had approximately five meals per day, but they were longer in duration than pigs in small group pens. There were no significant differences between average daily gain in LGAS systems compared to conventional small group housing. Comparable performance indicates that pigs can successfully adapt to the LGAS system.

The study at the commercial farm examined the change in eating behavior as pigs aged. Pigs studied in rooms varied six weeks in age. It was found that the average number of entrances into the food court each day decreased as the size (age) of the pigs increased, from nearly four entries per day at 88 lb., to about 2.5 visits per day at 198 lb.

Figure 2 depicts the diurnal pattern of eating by pigs, and shows that younger pigs had less of a dropoff in midday eating. These studies, compared to others, suggest that the younger pigs were limited in the number of feeder spaces and had to shift eating patterns from the normal peak periods to the less-intensive midday period.

Overall, pigs in large group auto-sort systems enter the food court 2-4 times each day and have fewer meals (5 vs. 10-15) than their small-pen counterparts. They compensate by increasing the length of their eating periods and move freely about the food court, eating from several feeders every day.

To ease the transition to large group systems, pigs should be introduced directly to the food court to make sure they know where the feed is located. The food court should be spacious so that pigs have access to all of the feeders; a feeder space should be provided for every 10-12 pigs.

Researcher: Harold Gonyou, University of Saskatchewan at Saskatoon, Saskatchewan. For more information, contact Gonyou by phone (306) 667-7443, fax (306) 955-2510 or e-mail harold.gonyou@usask.ca.