Economic impact of removing pigs before marketing on the remaining pigs’ growth performance

The economic impact of removing the heaviest pigs (topping) before marketing a finishing group and the effect of topping on performance of the remaining pigs were determined in 2 studies. In Exp. 1, a total of 1,126 pigs (BW = 241 lb; 25 pigs/pen) were randomly assigned to 1 of 3 treatments: topping 0, 2, or 4 pigs/pen 15 d before marketing the remaining pigs in the group. After topping, floor space per pig was 7.2, 7.8, and 8.6 ft2 for pens with 0, 2, and 4 pigs topped per pen, respectively. Overall (d 0 to 15), increasing the number of pigs topped per pen improved ADG (P \u3c 0.02), ADFI (linear; P \u3c 0.03), and F/G (quadratic; P \u3c 0.04). Revenues were similar (P \u3e 0.76) between treatments, but feed usage and cost was reduced (quadratic; P \u3c 0.01) as more pigs were topped per pen. However, there was no impact on income over feed cost (IOFC). In Exp. 2, a total of 1,084 pigs (BW = 234 lb; 27 pigs/pen) were assigned to 1 of 5 treatments. On d 0 (20 d before closeout), 2 pigs were topped from each pen excluding the control pens (0 top). Pens that were topped at d 0 had an additional 0, 2, 4, or 6 pigs per pen topped on d 10. Floor space per pig was 6.7 ft2 in control pens and 7.2 ft2 for the remaining pens from d 0 to 10. After topping on d 10, floor space per pig was 7.8, 8.6, and 9.5 ft2 for pens with 2, 4, or 6 more pigs topped, respectively. From d 10 to 20, the remaining pigs had increased (linear; P \u3c 0.01) ADFI, which led to a linear increase (P \u3c 0.01) in ADG. Overall, ADG and ADFI increased (linear; P \u3c 0.05) with increasing number of pigs topped, and F/G improved (P \u3c 0.01) in topped pens relative to intact pens. Weight discounts were highest in intact pens (P \u3c 0.02) compared to topped pens. Revenue decreased (P \u3c 0.05) as additional pigs were topped after d 10 in pens topped at d 0. Feed usage was highest (P \u3c 0.01) in intact pens. As more pigs were topped on d 10, IOFC tended to decrease (P = 0.07). Topping, regardless of number of pigs, did not affect (P \u3e 0.23) any of the carcass traits measured. Topping improves growth performance of the remaining pigs. Based on IOFC, topping 2 pigs once is the most optimal. Improvements in performance from topping more than 2 pigs were not great enough to overcome the reduction in total weight produced by the pen.; Swine Day, Manhattan, KS, November 19, 200