Economic optimization of culling strategies in swine breeding herds, using the “porkchop computer program”

Abstract

A computer model, PorkCHOP, has been designed (i) to quantify the benefits of increased lifespan in swine breeding herds and (ii) to optimize the replacement decision for sows with poor productive and/or reproductive performance. The model has been constructed in an electronic spreadsheet program for a microcomputer. It runs with default values, but allows the user to enter other data for all the variables considered, and therefore can easily be adjusted to individual farm conditions worldwide. In addition to research and teaching, the model is suitable for use in the field. PorkCHOP introduces a new economic index to use as a culling guide. This index is called the Retention Pay-Off (RPO), and indicates the total extra profit which retention of a sow is expected to yield over replacement, taking into account the risk of premature disposal. This index makes it possible to rank sows within the herd on future profitability. A value below zero indicates that replacement is the most profitable choice. Furthermore, the index is used to determine when to stop breeding if sows fail to conceive. The current (parity-specific) default values are chosen to be typical of U.S. herds with continuous farrowing and standard management practices. For herds in confinement under these conditions, some of the results obtained were: 1. (1) An economic optimum herd life of 10 parities for average producing sows. 2. (2) An increase in income between $17 and $31 per sow per year if the average parity at removal could be increased from 3.6 to 4.6. 3. (3) A financial loss of $1.33 per day delay in conception. 4. (4) First parity sows with a litter size of even 50% below average should not be culled on economic grounds. 5. (5) Average producing sows in the 1st, 2nd and 3rd parity can fail to conceive at least 3 times before replacement becomes the more profitable alternative. However, if reccurent fertilty problems are expected in future parities too, only 1 re-breeding is economically worthwhile. Sensitivity analyses showed that the results obtained differ according to the price and production circumstances involved. As big differences in these parameters occur between farms as well as between years within farms, a computerized approach such as PorkCHOP can greatly improve management decisions regarding sow-replacement.