Effects of Removal and Remixing of Heavyweight Pigs on Performance to Slaughter Weights1

An experiment was conducted to determine the effects of heavyweight pig removal and remixing on performance. The experiment used a total of 450 pigs (31 kg initial BW) that were sorted and remixed at a mean replicate BW of 73 kg. Treatments were 15 pigs/pen from initial BW to slaughter (15S), 20 pigs/pen from initial BW to time of sort and remix, then reduced to 15 pigs/pen (20/ 15), and 15 pigs/pen from time of sort and remix to slaughter, comprised of the 5 heaviest pigs from each of three 20/15 pens per replicate (15M). Space allocation was 0.56 m2/pig to the day of remixing and 0.74 m2/pig thereafter. There was no effect (P > 0.1) of treatment on ADG before 73 kg BW when pens were the experimental units. There was no effect (P > 0.1) of treatment on ADG or feed conversion to slaughter BW following removal and remixing using the contrast 20/15 + 15M vs. 15S. The average of the replicate for 20/15 and 15M was used as the experimental unit in a second statistical analysis. Daily feed was less (P = 0.079) from placement to 73 kg BW for the 20/15 + 15M population vs. the 15S population resulting in a lesser (P = 0.067) overall ADG (0.875 vs. 0.887 kg/d, respectively) with no effect (P > 0.1) on feed conversion or CV sample population BW. Removal and remixing of heavyweight pigs at a midpoint in the growth process had minimal effects on performance to slaughter and CV for BW at slaughter.