When asked how old your weaned pigs are, you likely respond with a simple answer like 21 days. But are the weaned pigs really 21 days old or is that just the interval from loading into the farrowing room to weaning? While it might be tempting to think this distinction is trivial, this is just one of many aspects of hog production where an overreliance on averages to measure performance has allowed for systematic inefficiency.
Chart 1 shows a packer matrix provided by USDA, and the value lost per head at marketing due to variation in weight. If you want to increase the value you receive from market pigs, it is important to begin managing variation as early as possible. While disease is the single greatest contributor to variation, there are other areas where we can make improvements, being more aware of the true age of our weaned pigs to name one example.
How Does Age Affect Variation?
To illustrate how age can contribute to variation, let’s use a simple scenario. A wean-to-finish unit receives 12-lb. weaned pigs. These pigs have an average daily gain (ADG) of 1.65 lb. and are marketed at 280 lb., or 163 days postweaning. Under these conditions, each day deviating from 163 will change the weight of the pigs by 1.65 lb.
Assuming these pigs were not all born on the same day, it follows that these pigs are at different points on the growth curve shown on Chart 2. Sows normally farrow after 115 days of gestation, with a standard deviation of 2.5 days. This means that 95% of farrowings occur in a 10-day range around the average, but for our purposes here we will narrow it to a seven-day range. In the below example, there is a range of weight from 274 lb. to 284 lb. due to differences in age alone. By adding in a range of wean weights (7.2 lb. to 16.8 lb.), the range of weight becomes 270 lb. to 289 lb. at finishing.
Where Does Growth Rate Factor In?
The next level of detail to add is different growth rates, with the light weaned pigs growing 10% slower and the heavier weaned pigs growing 10% faster. This addition expands the weight range at finishing to 243 lb. to 316 lb. at marketing. Chart 3 shows the increasing amount of weight variation from the three above scenarios. These calculations were done using linear growth rates. In the real-world, however, pigs grow non-linearly. Chart 4 shows the marginal growth of pigs, and at finishing, pigs are growing at the fastest rate, exacerbating these differences.
Although this analysis is simple and does not consider the complexities of real production, it does serve to demonstrate that small inefficiencies can grow into much larger ones that have significant economic consequences later. This is especially true in farms that source weaned pigs from multiple sow farms, where multiple age ranges can be combined. While there are certain ways to improve the grouping of farrowing days, addressing problems like these begins when we cease our overreliance on averages. There is a wealth of data from sow farms, it’s time to use it to the fullest.
Dennis DiPietre and Lance Mulberry are economists with KnowledgeVentures LLC.
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