Though they don't replace good management, slotted floors can reduce labor needs for raising hogs in confinement. A number of different kinds of design and construction are being used; here's an up-to-date report on them.
Roth, Fred W.
"A Situation Report - Slotted Floors for Swine: Design and Building,"
Iowa Farm Science: Vol. 17
, Article 2.
Available at: https://lib.dr.iastate.edu/farmscience/vol17/iss12/2