Lets start with a 250 lb live pig. Per Walter Jeffries at Sugar Mountain Farm, that pig would lose about 70 lbs of viscera and blood in the transition from live weight to 180 lbs hot hanging weight (freshly processed). That’s an initial loss of 28% of the initial weight. The animal loses another 3% during chilling due to additional moisture loss, taking us down to roughly 175 lbs chilled hanging weight. That weight still includes the head, trotters, tongue, etc which are generally not sold as commercial cuts. Removing those takes you down to roughly 125 lbs cut weight or 50% of your initial live weight.
Cooking will take your final yield down still further. Per the USDA, cooked pork yields somewhere between 74 and 96% of the cut weight, depending on the cut and cooking method. On average, cooked meat will yield 80% of the cut weight. (The big exception is bacon, which yields roughly 30%.) That takes your cut weight of 125 lbs down to 100 lbs cooked yield on your plate.
Using this process, we can extrapolate backwards from cut weight to find out the approximate live weight of an animal. Our pig Blackberry yielded roughly 175 lbs of cut weight, that means her other weights were as follows:
Hot Hanging Weight: 252 lbs
Chilled Hanging Weight: 244 lbs
Cut Weight: 175 lbs
Cooked Yield: 140 lbs
Our 350 lb pig on the hoof landed on the plate at a total of 140 lbs.
There is another method to determine the live weight of an animal without having to get the whole pig onto a scale. The “String Method” as described by Sugar Mountain farm uses the length of the pig from head (just between the ears) to the base of the tail and the girth of the pig right (behind the front legs) to estimate the total live weight.
For measurements taken in inches, the equation is as follows:
Live Weight = (Length x Girth^2) / 400
We neglected to measure Blackberry before she was harvested, but we still have one pig left on the hoof. We’ll measure tiny before processing to see how the math all shakes out. With luck her estimated live weight from the string method will be roughly the same as her estimated live weight extrapolating back from her cut weight. We’ll have to wait and see.