Pig body weight variation is a serious problem that is often overlooked until pigs are ready to go to market. Variation then becomes an urgent and significant management problem as pigs require sorting and remixing, and light weight culls are removed to another site so that facilities can be washed and prepared for the next group of pigs.

Pig body weight variation doesn’t just happen in the finisher. Variation magnifies itself throughout the life of the pig, and becomes greater as pigs age. For example, at weaning, the average weight of a group of pigs may be 13.0 pounds, with a range of body weights from 8.0 to 18.0 pounds. This is a 10.0 pound spread.  By the end of the nursery period, the average weight of this group of pigs may be 66.0 pounds, with a range of body weights from 46.0 to 86.0 pounds. The range of variation has now increased to 40.0 pounds.  By the time the group of pigs approach market weight, the variation in pig body weight from the lightest to the heaviest may be 100.00 pounds or more.

What is an acceptable amount of variation? Dr. John Patience from the Prairie Swine Centre in Saskatoon, Saskatchewan makes the following recommendations. For pigs at weaning, the Coefficient of Variation (CV) should be 20.0% or less. For an accurate estimation, at least 100 randomly selected pigs need to be weighed individually. For pigs coming out of the nursery, the CV should be 15.0% or less. For an accurate estimation, at least 50 randomly selected pigs need to be weighed individually. For pigs at market weight, the CV should be 10.0% or less. For an accurate estimation, at least 50 randomly selected pigs need to be weighed individually before the first group of pigs leaves the facility for market. To calculate the CV for any group of pigs, try using the Pig Weight CV Calculator spreadsheet.

There is Good News

The good news is that pig body weight variation can be reduced. Management practices and products that reduce variation early in a pig’s growth phase provide the biggest benefits. 

Research at the University of Minnesota documented that the variation in pig weaning weight was reduced from 19.0% to about 14.5% when pigs nursed sows consuming PUSH® feed at 0.36 lbs/ head/day. PUSH® feed not only reduced pig weaning weight variation, but also shifted the weaning weight distribution to the right (Figure 1), resulting in pigs that were both more uniform and heavier. 

To reduce variation even more, feed Gel to all pigs as they enter the nursery. Research at the LongView Animal Nutrition Center, has shown that pig weight variation in the nursery can be reduced by using Gel (Figure 2). Gel was fed 0.5-1lb/head/day for 7 days in total. After day 3-4, Gel was mixed in the feed. At the end of the nursery period, pigs that were not offered Gel had a CV for weight of 23.4, while pigs fed Gel had a CV for weight of only 21.0. In addition, pigs consuming Gel were 1.7 pounds heavier!

Begin with the end in mind.  To reduce pig weight variation at marketing time, feed PUSH® feed to sows in lactation and Gel to all pigs as they enter the nursery.

Learn more on www.GelResearch.com and www.feedPUSH.com

For further information, please see your local feed sales representative at a Land O’Lakes Feed Co-op or Purina Mills Dealer.Visit us online at www.LOLFeed.com, www.PurinaMills.com

Copyright © 2008 Land O’Lakes Purina Feed LLC. All rights reserved. PUSH is a registered trademark of Land O’Lakes Purina Feed LLC. Due to factors outside of Land O’Lakes Purina Feed’s control and because of market uncertainties, individual results to be obtained, including but not limited to financial performance, profits, losses or otherwise, cannot be predicted or guaranteed by Land O’Lakes Purina Feed