Removal of the heaviest market-weight pigs several days before marketing the whole group (topping) improves growth performance of the remaining pigs in the pens.

Although increasing the number of pigs topped leads to further boosts in performance, it's not enough to overcome the lower total weight of pigs sold at market.

Therefore, topping two pigs/pen is considered the most optimal management practice based on income-over-feed cost (IOFC).

In addition to improving growth performance, topping reduces variation and weight discounts because more pigs fall within the preferred weight window of specific packers. Topping also reduces overall feed usage and cost.

But producers need to follow the optimal or most economically feasible number of pigs to top based on IOFC. Topping at least two pigs twice (20 and 10 days before marketing the whole barn in this study) improved growth performance the most. But topping two pigs only once was optimal based on IOFC.

Kansas State University conducted two studies to evaluate the economic and performance impacts of removing the heaviest pigs before marketing a finishing group.

In the first trial, a total of 1,126 pigs weighing an average of 241 lb. and allotted 25 pigs/pen were randomly assigned to one of three treatments: topping 0, two or four pigs/pen 15 days before marketing the remaining pigs in the group. After topping, floor space/pig was 7.2, 7.8 and 8.6 sq. ft. for pens with 0, two and four pigs topped/pen, respectively. Overall, increasing the number of pigs topped/pen improved average daily gain, average daily feed intake and feed/gain (Table 1). Revenues were similar between treatments, but feed use and cost were reduced as more pigs were topped/pen.

However, there was no impact on income over feed cost, according to the KSU study.

In the second experiment, a total of 1,084 pigs weighing an average of 234 lb. and housed 27 pigs/pen were assigned to one of several treatments. On Day 0 (20 days before group closeout), two pigs were topped from each pen except for the control pen.

These pens had an additional 0, two, four or six pigs topped/pen on Day 10. Floor space/pig was 6.7 sq. ft. in control pens and 7.2 sq. ft. for the remaining pens from Day 0 to 10.

After topping on Day 10, floor space/pig was 7.8, 8.6 and 9.5 sq. ft. for pens with two, four or six more pigs topped, respectively.

From Day 10 to 20, the remaining pigs had increased average daily feed intake, which led to an overall increase in average daily gain.

In this study, average daily gain and average daily feed intake increased as more pigs were topped, and feed/gain improved in topped pens compared to intact pens.

Weight discounts were highest in intact pens compared to topped pens. But revenue decreased as more pigs were topped after Day 10 in pens originally topped at Day 0. Feed usage was highest in intact pens.

Importantly, as more pigs were topped on Day 10, IOFC tended to decline.

Topping, regardless of the number of pigs involved, did not impact any of the carcass traits measured.

Results for the second study can be found in Table 2 and Table 3.

Based on IOFC, topping two pigs once is the most optimal marketing program, whereas performance improvements from topping more than two pigs didn't outweigh the reduction in total weight produced by the pen.

Researchers: Jay Jacela; Steve Dritz, DVM; Mike Tokach; Joel DeRouchey; Robert Goodband; and James Nelssen, all of Kansas State University. For more information, contact Jacela by phone (785) 532-4845, fax (785) 532-4288 or e-mail jjacela@ksu.edu.