Kenyan army spokesman Colonel Cyrus Oguna told reporters on Saturday that levels of casualties were very high in air strikes on Friday, adding the bombing raids hit rebel positions in Garbahare in southern Somalia's Gedo region.
"Provisional casualties are that Al-Shabab lost 60 or more fighters, and more than 50 were injured," Oguna added.
Al-Qaeda linked Shabab rebels have repeatedly dismissed Kenyan casualties reports as lies, and it was not possible to independently confirm the deaths.
Kenya sent troops across the border into Somalia in October to battle the hardline militants it blamed for a spate of attacks on home soil, and are fighting alongside Somali pro-government forces.
"We will keep hitting them (Shabab) until their spine is completely broken ... and we will relish that moment," Oguna added.
Hardline Shabab fighters control large parts of central and southern Somalia but are facing increasing pressure from government forces and regional armies.
Ethiopian forces moved across its border into Somalia in November, and last month fought alongside pro-government gunmen to wrest control of Beledweyne in central Somalia's Hiran region from the insurgents.
Kenya said it had exchanged liaison officers with the Ethiopian army since they both faced a common enemy, but that the two fronts remained separate.
"The Ethiopians ... might ease pressure because Al-Shabab will be spread out with more enemies to fight, but they have their operation, and we have ours," Oguna said.
A 10,000-strong African Union force, made up of troops from Uganda, Burundi and Djibouti, is defending the fragile Western-backed government from Shabab fighters in the war-torn capital Mogadishu.