Beef stockpiles in the nation’s freezers shrank to a five-year low at the end of May and pork fell to a 2 ½-year low, government data showed, underscoring the tightening supplies that helped fuel rallies in cattle and hog prices.

U.S. beef supplies totaled 363.8 million pounds as of May 31, down 13 percent from the same date a year earlier, the USDA said in its monthly Cold Storage report released Tuesday. Pork stocks totaled 448.3 million pounds, down 23 percent.

Supplies may continue to shrink, or at least remain near multi-year lows, analysts say. Beef and pork producers cut herds after suffering heavy losses amid high feed costs and weaker demand in recent years, and there are few signs of expansion even as they regained profits. Earlier this spring, the number of cattle on feed fell to a six-year low.

“With beef production forecast to fall at least through 2011, we would not be surprised to see (cold storage supplies) fall further,” livestock analysts Steve Meyer and Len Steiner said in a report today.

Last month’s supplies were the lowest since June 2005 for beef and the lowest since December 2007 for pork, Meyer and Steiner said.

Other analysts said the cold storage data reinforced the bullish case for cattle and hog prices, which have recently rebounded from a steep slide in May.

Cash hog prices may climb another $2 to $3.50 per hundred pounds given “very tight” supplies of slaughter-ready animals, Mike Zuzolo, president of Global Commodity Analytics & Consulting LLC, said in a report yesterday.

Live hogs sold for $63 to $63.50 per hundredweight earlier today in major Midwest markets, according to USDA data.

In Chicago futures trading, July lean hogs fell 0.65 cent to 81.3 cents per pound late today. While July hogs are down 7.4 percent from a contract high of 87.75 in April, the contract is still up 6.8 percent from the end of last year. Chicago futures are based on carcass prices.

August live cattle futures fell 0.225 cent to 88.575 cents per pound, up 9.6 percent from the average front-month futures price in June 2009.

The USDA cold storage report also carried some potentially troubling numbers for beef and pork producers.

Chicken supplies at the end of last month totaled 699.5 million pounds, up 11 percent from the end of April and up 9 percent from May 2009, the USDA said.

An abundance of cheaper chicken may hurt beef and pork demand, analysts have said previously, especially if high unemployment and a sluggish economy prompts consumers to forgo higher-priced food.