Typically, releases of the Quarterly Hogs and Pigs report series are greatly anticipated by the U.S. pork industry for their nationwide perspective on animal numbers. The December report was probably more anticipated than usual after lower than expected fall 2013 slaughter numbers and detection of Porcine Epidemic Diarrhea (PED) in the U.S. swine herd.

The Quarterly Hogs and Pigs report issued on December 27 met expectations by providing extensive revisions to 2013 inventories and by giving some first indications of how PED may be affecting the U.S. pork industry.

The December report revised first-half 2013 farrowings downward, one effect of which was to bring succeeding inventories into line with observed second-half 2013 slaughter numbers. First-half farrowings were lowered 2.8 percent from 5.765 million farrowings in 1H13 (December 2012-May 2013) to 5.605 million farrowings. The record-high first-half litter rate—10.19 pigs per litter—was left unchanged.

Lower first-half farrowings translated into lower market hog inventories for March, June, and September. Reductions in March and June market hog inventories were concentrated in the lighter weight categories. Changes in the September 1 market inventory were concentrated in the higher weight category, which in turn comports better with observed fall slaughter numbers.

The December report estimated that September-November farrowings, at 2.882 million head, were just slightly below those of a year earlier. And while the reported litter rate of 10.16 pigs per litter was slightly above a year earlier, the September-November litter rate grew at a slower pace than the trend established earlier in the decade.

The red point in the figure below—closer to 10.3 pigs per litter—is more consistent with growth dynamics of the recent past. Because PED is known to strike very young animals—with mortality rates of up to 100 percent—the September-November litter rate may be picking up effects of PED in the breeding herd.

The PED epidemic may also be showing up in the lowest weight class of the December 1 market hog inventory. On December 1, 2013, the under-50-pound weight class was 1.3 percent below a year earlier. The report also indicates that States reportedly hit the hardest by PED showed the steepest year-over-year declines in under-50-pound pig inventories: Iowa’s December 1, 2013, inventory of under-50-pound animals is 3.3 percent below its December 1, 2012, inventory. North Carolina’s under-50-pound pig inventory is 10.6 percent below a year ago, and Oklahoma’s is down 30 percent from December 2012. The vulnerability of young pigs to PED suggests that the disease is having a demonstrable effect on national pig numbers.