Weight variation among pigs is a natural biological occurrence that begins at birth and multiplies as the pigs grow and can result in discounts when pigs that are either too heavy or too light reach the packing plant.

Dr. Dennis Dipietre, an economist with Columbia, Missouri based Knowledge Ventures, says many commonly accepted practices add to that variation so, when pigs achieve typical market weights, there's often a spread of about 100 pounds between the smallest and the largest.

Dr. Dennis Dipietre-Knowledge Ventures

If we look at particular practices that cause problems, we know for instance and are correcting that we've driven lactation length much too low.

We did that to try to get the of pigs volume up but, when you separate a pig at 17-18 days from the sow, not only do you do damage to the pig but you also damage reproductive future performance of the sow.

So certainly moving lactation length up to 21 to 23 days is beginning to be a common practice now.

Some of the other things that are just the typical fumbles that we sometimes make on the farm, we have more feed-out events than some producers really realize or water-out events.

Those kinds of stressers to pigs create more variation in grow, especially among the weaker pigs.

I don't mean the five or ten out of a thousand in a building that are obviously sick.

I mean the 300 lightest pigs in a thousand head barn are going to be hurt probably by this much more than the 300 more robust heavier ones.

Dr. Dipietre says his data shows that reducing variation by as much as 30 per cent can add as much as five dollars per head in net return.