U.S. livestock futures closed down Monday as markets fell broadly and a summer heat wave threatened to temper consumer demand for meat.

Hogs futures also fell on suspicions the summer heat will shrink consumer meat demand.

August hog futures closed down 0.5 cent, or 0.5%, to 99.27 cents a pound in trading at the Chicago Mercantile Exchange. CME October hog futures fell 1.35 cents, or 1.5%, to 90.3 cents a pound.

Hot summer temperatures aren't as challenging for the hog complex since hogs are often housed indoors, where producers can better regulate temperatures. Producers can also more easily wait to sell animals if they slow their eating and stop gaining weight.

"The animals just quit eating, kind of like we would do if we were outside," said Don Roose, president of brokerage U.S. Commodities Inc. He expects carcass weights, or the sizes of slaughter-ready animals, to start falling in coming days.

Cash hog prices were reported mostly steady. Some pork processors need additional hogs for arrival later in the week. The severe heat wave across much of the Midwest may reduce feed consumption and slow weight gains enough to result in fewer hogs offered for sale, considered supportive for prices. The heat, however, could also negatively affect consumer demand for meats since people tend to eat lighter meats during the hottest period of the summer.

The USDA's pork carcass composite value, a measure of wholesale prices, on Friday rose $1.41 to $100.07 a hundred pounds, the highest since June 27.

The terminal markets traded steady to up $1 with top prices from $63 to $65 a hundred pounds on a live basis.