# Practice tip March and April, 1998

## How do you calculate the cost of a sow nonproductive day?

There are several methods of estimating the cost of a nonproductive sow day. One method is to calculate the cost of maintaining a nonlactating sow. A new crated-sow gestation building costs about \$600 per crate. If that is depreciated over 10 years there is cost of \$60 per space per year or \$0.16 per day. Taxes and insurance would round that up to \$0.17 per day.

Feed is the major cost. A nonlactating sow will get 5 lb per day at \$.07 per lb or \$0.35 feed per sow per day. Nonfeed gestation variable costs will be about 1/3 of feed costs or \$0.12 per day. If we total the depreciation, taxes, and insurance (\$0.17) plus feed (\$0.35) plus nonfeed variable (\$0.12) the cost of maintaining a nonlactating sow is \$0.64 per day, whether she is pregnant or open. Obviously if she is open there will be no pig produced income. However, she is gaining half a pound per day which is probably worth about \$0.16 when and if she is sent to market.

Another method is to estimate the opportunity cost of not having a pig farrowed, proposed by Dr. Morgan Morrow. He assumed a sow produces 20 pigs per sow per year or 0.0548 pigs per day. If the marginal profit on a 250-lb market hog is \$30, then the opportunity cost of a nonproductive sow day is \$1.64 (.0548 pigs per day x \$30 per pig).

Another method would be to look at the profit on a weaned-pig basis, as a quoted market is developing for them and the sow probably should not receive credit for profits or losses after the pig is weaned. Cost of producing weaners is around \$27-\$33 head. If you can sell the weaner for \$35, that is about an \$8 (\$35-\$27) profit. Following on Dr. Morrow's 0.0548 pigs produced per day x \$8 profit per weaner, the opportunity cost is \$0.44 per day, which is probably less than what it costs to maintain a nonlactating sow.

As you can see, there is not any one best method to calculate the cost of nonproductive sow days.

--Submitted by Dr. Palmer J. Holden
Iowa State University

This practice tip was based on a posting to SWINE-L