Target weight calculator for heavy hogs

Introduction

A combination of maximizing revenue and reducing the costs of production determines whether pork producers make a profit on the hogs they raise. The revenue side of the equation often depends on getting the hogs to market at just the right time.

The target carcass weight, determined by a hog grading grid, is the primary factor determining when to send hogs to market. A variety of factors, from pig variation to space requirements to holidays, influence shipping practices, resulting in a less-than-perfect fit with the grading grid's target range. Pork producers can control some of these factors or manage them to maximize financial returns.

Sort loss

Carcasses that miss the grading grid's targets for lean yield or weight don't earn their potential maximum revenue. While the settlement statement doesn't itemize the value of this loss, tallying the numbers of carcasses on the statement that didn't fit into the target and calculating the resulting revenue missed will give an estimate of the loss. Even if the average weight and average lean yield of a group appear to hit the target, many carcasses may, in fact, lie outside it. While an average weight for a pen may seem adequate for shipping, it's important to remember that buyers grade and price carcasses individually.

In herds where pork producers closely monitor weights and ship hogs weekly, 66% of carcass weights fall within plus or minus 4 kilograms (kg) of the average weight^{footnote 1[1]}. Some grids will accommodate biweekly shipping without penalty as long as weight is accurately monitored. With a narrow grid, accurate weekly shipping can be very important.

To minimize this source of lost revenue, pay careful attention to the grading grid being targeted and know the shipping weight necessary to achieve the best possible fit with the targeted carcass weight and lean yield. Understand the growth characteristics of the pigs and the dressing percentage (DP) at the packing plant by routinely reviewing shipping weights and the resulting settlement statement.

Knowing how shipping weight affects carcass weight and lean yield will help pork producers effectively adjust their shipping strategy. Getting the shipping weight right is a fundamental starting point. There is always variation in a herd, but here is a good place to manage it, at least to some extent. Grading grids use a sharp cut-off, not a gradual one, and hitting the next higher weight class could mean a loss of significant index points, resulting in lost revenue.

Start with an accurate weigh scale. Accurately weighing pigs prior to shipping can result in greater returns than possibly any other manual effort in pork production. A survey of 34 pork producers in Kansas showed that the estimated return from one employee spending 2 hours per week weighing market hogs ranged from US$41.53 to US$190.38 per hour, depending on the sort loss to begin with^{footnote 2[2]}. Using automatic sorters can also aid hog weighing.

A second tool for quickly determining the required shipping weight, depending on the target carcass weight and DP, is the hog target weight calculator (Figure 1). Use the target weight calculator to see what carcass weight is likely to result from shipping hogs at a given live weight, or to see what effect a change in DP (which may result from extended transport times) might have on carcass weight.

Handling decisions can also affect carcass quality; shipping time is not the time to take chances with the investment already made in a finished animal. See the publications Guidelines for Transporting Pigs and Caring for Compromised Pigs, available from Farm & Food Care Ontario.

Influencing factors

Target carcass weight:

• is determined by your grading grid
• depends on dressing percentage and live weight
• requires producers to know their grid and targets, and to weigh their pigs

Dressing percentage:

• transit time
• slaughter time (know your schedule)
• feed withdrawal/gut fill
• diet composition

Target weight calculator

The target weight calculator diagrammatically relates carcass weight, carcass DP and live weight. The calculator can determine a shipping weight given a target carcass weight and an estimate of DP (or vice versa). Figure 1 shows the Hog Target Weight Calculator with shipping weight provided in kilograms and pounds.

Using the calculator, producers can determine the target shipping weights for their hogs, based on the current grid, or the potential shipping weight, based on the target weight range of a new grid. They can also estimate the carcass weight resulting from shipping hogs at a given live weight, or determine what effect a change in DP might have on carcass weight.

Using the calculator

1. Find the target carcass weight (from your grid) on the left axis.
2. Estimate your DP (from records, or use 80%).
3. Use a straight edge to read across from the target carcass weight through the DP to find the target live weight.
4. Reverse the procedure to determine carcass weight based on a given live weight.

Example

Consider a target carcass weight of 110 kg. Assuming a DP of 80%, we can read from 110 kg (carcass weight, left side) through the 80% point to arrive at a target live weight of about 137.5 kg on the right side.

Marginal feed cost and marginal return

After pigs have reached the minimum weight demanded by the grading grid, consider whether it is profitable to continue to feed to higher weights. This is particularly important when feed cost is high, and even more so if market prices are also low. It also assumes that the main driver is not the need to free up the facilities for incoming animals.

To make an informed decision, producers will need good information on the feed conversion ratio (FCR) of the herd over the relevant weight range. This is important, since the FCR may decline as animals get larger and can really only be estimated with any accuracy by measuring it in the barn. Lean yield can also change at heavier weights. Monitor this from settlement statements, through Ontario Pork's online database or by using OMAFRA's Grading Data Explorer program, available for download on Ontario Pork's website. This information allows producers to make incremental calculations of the added cost of feed and the added value of the carcass, and determine the optimum shipping weight.

Conclusion

The information required for making good marketing decisions and the advice and tools for interpreting the information are all available. Putting it all together is worth the effort.

This fact sheet was written by Jaydee Smith, production lead, Ontario Ministry of Agriculture, Food and Rural Affairs, Ridgetown.