Chicago Mercantile Exchange (CME) lean hog futures fell to their lowest level in more than a week on Monday before ending unchanged, as concerns about risks for the spread of avian influenza in livestock hung over the market, Reuters reported, citing analysts.

Live cattle and feeder cattle futures ended lower.

Livestock markets have swung on worries about the H5N1 virus since the US Department of Agriculture (USDA) confirmed cases in dairy cows for the first time in late March. The USDA has since reported outbreaks in nine states, though scientists think outbreaks are more widespread based on findings of H5N1 particles in about 20% of milk samples.

Concerns about the disease create nervousness among funds that hold net long positions in hog futures, said Altin Kalo, agricultural economist for Steiner Consulting.

Traders worry about the risk for the virus, known as highly pathogenic avian influenza (HPAI), to spill into hog herds. USDA has reported no cases in pigs.

"You have increasing uncertainty because of all the HPAI spreading in cattle," Kalo said. "The fear is: We didn't know it was going to get into cattle."

CME June lean hogs ended at 102.475 cents per pound after dropping earlier to 101.30 cents, its lowest level since April 18.

CME June live cattle settled down 1.425 cents at 177.150 cents per pound. August feeder cattle ended 0.925 cents lower at 259.625 cents per pound after rising earlier to its highest price since March 26.

The US government said it is collecting samples of ground beef at retail stores in states with outbreaks of avian influenza in dairy cows for testing, but remains confident the meat supply is safe.