During the 11 weeks from early June through mid-August, federally inspected hog slaughter totaled 19.7 million hogs, 4.6 percent more than in 2001. USDA number had projected slaughter to be up 4.5 percent for this period, so Plain credits them with a near perfect forecast for that period.

However, during the last four weeks, federally inspected hog slaughter has totaled 7.9 million, up 7.7 percent from the corresponding weeks in 2001. The lightweight inventory in the June implied that slaughter would be up only1.3 percent during this period, says Plain.

There are several possible explanations for the differences. One explanation is that USDA underestimated the lightweight inventory of market hogs on June 1. But, that is not the only explanation says Plain.

As losses mount, producers have been sending sows to slaughter at a much faster pace this summer than last. Subtract the additional sows and hog slaughter during the last four weeks is up 6.9 percent, rather than 7.7 percent, according to Plain.

Producers are retaining fewer gilts for breeding this summer than they did last summer. Adjust slaughter during the last four weeks for both extra sows and gilts and slaughter is up only 5.3 percent.

Plain says there is some evidence that producers may be more current in their marketings than they were at this time last year. The average carcass weight during the last four weeks appears to be off a little over half a pound from a year ago. Adjust slaughter for extra sows, gilts and a half-day pull-forward in marketings and hog slaughter is only up about 2.6 percent compared to last year.

Plain notes that if slaughter continues at the current pace, fourth quarter hog prices could be lower than 1998. However, if some of the factors talked about in this column are true, the jump in hog slaughter could be temporary.