Effect of social rank on pig performance and feeding behavior with conventional and electronic feed intake recording equipment

Previous studies determined and applied a rank to pigs based on specific agonistic behaviors and did not determine the effect of rank on feed intake, growth performance, and feeding behavior. This experiment was conducted to determine the effect of rank for pigs based on wins using two types of single-spaced feeders (conventional vs. electronic). Winning was defined as a pig that turned away a pen-mate with any combination of bites, pushes, head jumps, bites to the rump, occurring anywhere in the pen, or caused displacement at the feeder. The percentage of wins decreased with rank based on wins for rank numbers 1 to 8, respectively. There was a general trend for the percentage of total interactions to decrease with rank number for rank based on percent wins. The percentage of total interactions decreased with rank based on total interactions for rank numbers 1 to 8, respectively. These results suggest that under conditions of this study that used barrows fed on either conventional or electronic feeders, pigs can be organized into a rank order based on wins. This study suggests that utilizing a rank based on percent wins or percent total interactions will present the strongest correlations with percent wins and total interactions. A within-pen rank (1 to 8) of pigs based on highest to lowest percent wins was developed from video recorded interactions during the second day after mixing. Feed intake and average daily gain (ADG) were not different for pigs using conventional verses electronic feeder types. Pigs on the electronic feeders had a higher Gain:Feed (G:F) ratio for the 28-d test. Daily feed intake, ADG, and G:F ratio was not significantly different among rank numbers. There was an effect of rank on the number of feeder visits per day and on feed consumption rate. This study suggests that pigs given ad libitum access to feed on electronic feeders and ranked based on wins were not different in feed intake and growth performance. The effect of rank based on wins provided differences in feeding behavior, specifically the number of feeder visits per day and feed consumption rate.