The milk-feed ratio ― a rough measure of dairy producer profitability ― has never been this low.

Thursday afternoon, the U.S. Department of Agriculture reported that the preliminary milk-feed ratio for May was 1.38. That broke the previous record of 1.45. (It should be noted that the 1.45 figure reported for April 2012, which tied June 2009, was now been revised down to 1.42.)

None of the milk-feed ratios on record, going back to 1985, have ever been this low.

May’s number reflects high feed costs and a declining milk price.

The all-milk price used by the USDA in calculating the ratio dropped from $16.80 per hundredweight in April to $16.40 in May.

May’s corn price was down slightly from April ― $6.22 per bushel versus $6.34 ― but the soybean price remained at the same high level ― $13.70 per bushel ― and alfalfa hay increased $8 per ton to $215.

Some people question how valid the USDA’s milk-feed ratio is. See this story. But the USDA has been using the same formula for years, comparing the same commodities. Therefore, it can serve as a relative measure for comparing different points in time.

The ratio is found in the USDA’s monthly “Agricultural Prices” report.

There is some hope, however. Since May 15, the block cheese price on the Chicago Mercantile Exchange has risen 12 cents per pound -- from $1.50 to $1.62. Often, that portends an increase in the milk price. A one-cent change in cheese will move the Class III milk price by 10 cents, according to a common rule-of-thumb.