A real dilemma in today’s production world is that 5-10% of pigs delivered to a finisher never makes it to an acceptable slaughter weight and are sold discounted, off the market. Land O’ Lakes Purina Feed has developed a strategy to reduce the number of underweight pigs at slaughter.

First, let’s get an understanding of where these small pigs are coming from:

Small Birth Weights — They are born that way! Many of the light weight pigs delivered to our finishing systems are small at birth. Some of them come from:

  1. Large Litter Sizes — Sows that have large litters(>15 pigs) tend to have small birth weight pigs. The uterus does not have space and the ability to supply enough nutrients to every pig in a large litter.
  2. Older Parity Sows — As sows age and go through the farrowing process their uterus becomes damaged and they lose the ability to maintain an even litter size. Older sows have more variation in their litter birth weight and therefore, more small pigs.
  3. Thin Sows — Under-conditioned sows will have small birth weight pigs.
  4. Early Farrowing Sows — Sows farrowing less than 114 days of gestation will have reduced birth weight litters.  Producers will need to be especially careful not to induce farrowing prior to day 115 of gestation.

Farrowing House Management — A variety of problems can occur in farrowing rooms that result in small, light weight pigs at weaning, such as:

  1. Poor Cross Fostering — All pigs need a good supply of milk. Pigs falling out should be moved to nurse sows to ensure good intake of milk.
  2. Health Problems — Diarrhea or any other health problem will reduce weaning weights and increase variation among litters.
  3. Decrease in Sow Lactation Intake — Summer heat, off feed sows will cause a reduction in weaning weights and more small pigs at weaning.
  4. Decrease in Weaning Age — A decline in weaning age will produce lighter pigs at weaning.

We must be diligent and correct in as many of these problems at the sow farm as possible to reduce the number of small, light weight pigs coming to our nurseries and wean-to-finish barns.

How are small pigs handled when they reach the nursery or wean-to-finish barn?

Most small pigs are fed a standard feed budget on the average weight of the pigs placed in a barn (Table 1).

Table 1.  Standard Budget for 12 pound Weaned Pig Delivered from a Sow Farm.

UltraCare® 100 feed

UltraCare® 200 feed

UltraCare® 300 feed

UltraCare® 400 feed

UltraCare® 500 feed

0 pounds

4 pounds

7.0 pounds

14.0 pounds


What about the small, light weight pigs?

Let’s look at what they consume versus what they actually need (Table 2).

Table 2.  Actual and Needed Feed Consumed by Small, Light Weight Pigs.


UltraCare®100 feed

UltraCare®200 feed

UltraCare®300 feed

UltraCare®400 feed

UltraCare®500 feed


0 pounds

3  pounds

5.7  pounds

11  pounds



3  pounds

5  pounds

7  pounds

14 pounds


In this example, the small pigs needed 8 pounds of the first 2 diets to meet their biological needs. However, since the farm only uses a single feed budget these smaller, light weight pigs only received 3 pounds of UltraCare® 200 feed because of their small size and lower intake. 

What can be done to solve the problem?

Producers need to implement a small, light weight pig budget. Producers need to:

  • Sort the smallest 10-20% of the pigs into designated small pens.
  • Place a feed card on their feeder with the desired amount of feed per diet to be fed.
  • Use bags or a separate bin to feed the small pigs. 

NOTE:  Small pigs will lag about 1 week behind the rest of the group in diet changes.

What results can producers expect? 

Feeding the small pigs differently can result in a 4-5 pound heavier pigs as they exit the nursery phase. The smallest pigs in an average group of 50 pound pigs will now weigh 40 pounds rather than 35 pounds.

How does this transfer into the finishing barn?

Let’s look at what happens 125 days later to pigs in the finishing barn (Table 3).

Table 3.  Initial and Market Weights of Average and Small Pigs Fed the Standard Budget or Feeding the Small Pigs a Separate Feed Budget.                                                                 


Initial Weight to Finisher (pounds)         

Market Weight

  Average pigs



  Small Pigs



  Small Pigs Fed Right



NOTE:  The 5 pound spread has now gone to 35 pounds at the end of finishing.

What’s the financial impact on feeding the small pig correctly on the bottom line (Table 4)?

Table 4. Value per Head of Feeding Small Pigs the Standard Budget or on a Separate Feed Budget.                                                           


Market Weight (pounds)

Market $ / cwt                






Small Fed Right




In this case for every pig pushed into a desirable weight category, producers gain $38.80 per head.


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, www.PurinaPigStarters.com, www.GelResearch.com

Copyright © 2008 Land O’Lakes Purina Feed LLC. All rights reserved. UltraCare is 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.