The numbers are there. If you're looking for a digested summary from the USDA itself, here is an old 2002 analysis of the 1997 farm census. With industrial farm consolidation continuing since then I can't imagine it's improved. Key point here is the value of sales.
"Of the 1,315,051 farms with livestock, 18 percent (237,821 farms) were farms with confined livestock types (i.e., farms with 4 or more animal units of any combination of fattened cattle, milk cows, swine, chickens and turkeys, or appeared to be raising veal or heifers in confinement). These 237,821 farms accounted for $79 billion in gross livestock sales, which was 80 percent of gross livestock sales for all farms."
Nice example of a pareto distribution. Eighty percent of our meat comes from the roughly twenty percent of factory farms that confine their livestock in tiny cages.
"Of the 1,315,051 farms with livestock, 18 percent (237,821 farms) were farms with confined livestock types (i.e., farms with 4 or more animal units of any combination of fattened cattle, milk cows, swine, chickens and turkeys, or appeared to be raising veal or heifers in confinement). These 237,821 farms accounted for $79 billion in gross livestock sales, which was 80 percent of gross livestock sales for all farms."
https://www.nrcs.usda.gov/wps/portal/nrcs/detail/?cid=nrcs14...