Its Not as Simple as Leveling the Playing Field
Reduction in variation of growing pigs can have significant impacts on both cost of production and on return from the packer. This double impact on both cost and return makes this an especially lucrative subject for both study and the development of strategy leading to standard operating procedure (SOP) creation or amendments. Simply reducing variation is not the goal however since there is no guarantee that this will produce either cost reduction or income increase.
The goal is to manage variation is such a way as to increase the number of animals which end the production process according to a specification which creates more value. We know that almost all packer grids are constructed to reward animals which produce the highest value for the plant and its associated down-stream product markets. Plants which primarily bone out all of the major primals generally prefer larger carcasses since each knife cut yields more product and therefore lowers cost. However, primals which exceed certain sizes wind up with very heavy discounts in the wholesale trade since cuts don’t fit plate standards.
In general, producers today achieve a very wide distribution of final outcome with respect to marketed weights. Some smaller farms which use auto-sort systems effectively have created a sizeable income increase by matching weights to high paying boxes in the packer grid. However, achieving this sorting uniformity still may produce long closeout periods which can lower building use efficiency or require more total finishing spaces for a given annual production total.
If you achieve more uniform growth by speeding up the slow doing pigs and slowing down the faster growing ones, you penalize the growth potential of the best performing pigs. This is sometimes the inadvertent result of too much cross-fostering and pen sorting in the nursery phase (for instance). One strategy which has been proposed by John Deen has been to focus attention on the lowest performing 30% so that reduction in variation is achieved by treating (both with increased husbandry and appropriate medications) the more unthrifty portion of the distribution while allowing the best performing pigs to continue their thing unimpeded. Sounds like a good idea.