Only a few months in a feedlot.Not sure it's been mentioned in this thread yet but preliminary studies have shown that a very small amount of seaweed added to cow feed can reduce their methane production by up to 82 %
Over the course of five months last summer, Kebreab and Roque added scant amounts of seaweed to the diet of 21 beef cattle and tracked their weight gain and methane emissions. Cattle that consumed doses of about 80 grams (3 ounces) of seaweed gained as much weight as their herd mates while burping out 82 percent less methane into the atmosphere. Kebreab and Roque are building on their earlier work with dairy cattle, which was the world’s first experiment reported that used seaweed in cattle.
I don't see greenhouse gasses and meat as being an insurmountable obstacle
Cost
Only one rare species of seaweed
Up to 82%... Average 45%
Wishful thinking