A pilot study on auto-sort technology conducted by the University of Illinois into the well-being of wean-to-finish pigs found there were pluses and minuses to each auto-sort system evaluated.
Auto-sort does improve the loading process as indicated by the decreased amount of time it takes to load and unload pigs, ease of handling and ease of movement through the packing plant.
But researchers noted that several improvements still need to be made on each auto-sort layout evaluated in this study to make them more cost-effective before completely implementing.
In the study, weaned pigs were assigned to one of three auto-sort layouts:
Food court, where around 600 pigs go through the scale to enter the “food area;”
Water pen, where around 600 pigs enter the scale from the water pen to reach the “food area;” and
Fast lane, where around 600 pigs have food and water in each “zone” and at the end of the last zone, pigs must go through a scale to return to the fast lane.
The control was a large, conventional pen with 300 pigs per pen in two pens.
The food court layout is the most efficient and has the potential to improve growth rate if the layout design is optimized.
Pig behavior was monitored during loading, training and at certain times through the wean-to-finish phase. Blood samples were taken to assess the impact of auto-sort systems on stress hormones and pig immune status. Performance measures were recorded. The study was replicated three times.
Figure 1  shows the impact of handling pigs from all treatments when removed from the pen and loaded onto the truck.
Figure 2  shows the time it took to load individual pigs from each treatment group onto the truck. Pigs removed from the conventional pens and the food-court layout were more difficult to handle.
But all of the pigs from the auto-sort systems were easier to load than pigs kept in conventional pens. The loading time (seconds per pig) was greater for conventional pens than for any of the auto-sort layouts.
In particular, pigs from fast-lane and food-court auto-sort layouts loaded the fastest. In fact, pigs from the auto-sort pens required less prod use and vocalized less during loading than conventionally raised pigs.
However, more lame pigs were observed in the food-court treatment than in any other system.
All pigs in the auto-sort layouts quickly learned how to navigate the system within the first few days of having access to the scale.
Conventionally raised pigs were more aggressive than either the pigs in the fast-lane or water-pen layouts.
Pigs in the food-court layout spent more time fighting than did any of the other auto-sort systems, which may be due to the limited number of waterers in the food pen during the late finishing phase. That may also be a factor leading to more lame animals during loading and affecting maximal growth rate potential.
Blood samples were taken before loading and transportation to slaughter and again after unloading at the plant.
Figure 3  denotes that prior to any loading or handling stress, conventional pigs had the highest stress levels.
However, following handling and transportation, all pigs from the auto-sort layouts showed an increase in plasma cortisol; pigs from the food-court pens had the greatest increase in cortisol, suggesting an acute stress response to handling and transportation.
Immune test results indicated that pigs raised in conventional pens recorded a classical acute stress response to handling/transportation stress, while auto-sort pigs didn't.
Pigs from the food-court pens had greater insulin-like growth factor (IGF-1) than any other treatment group, indicating possible potential for improved growth rate.
Figure 4  shows that sort loss was greatly affected by treatment. Of the auto-sort layouts, the least amount of sort loss ($173.41) was found in pigs raised in food-court layouts, followed by pigs from the water-pen layout ($180.19). The greatest sort loss ($396.54) was recorded for pigs from the fast-lane layout.
Table 1  represents the performance measures for all treatments. The conventionally raised pigs had the fewest number of days to market, greatest average daily gain and hot carcass weight, while the food-court layout pigs had the best feed efficiency ratio.
Researchers: Janeen L. Salak-Johnson and Ashley DeDecker, University of Illinois. For more information, contact Salak-Johnson by phone 217-333-0069, fax 217-333-8286 or email [email protected] .