Per this book there was the idea promoted by several people in 1910 to bring hippopotamus ranching to America. The idea was to alleviate the then current meat shortage and to free up rivers that were being choked (at that time) by the invasive Japanese Hyacinth which the hippos would eat.
The attempt to import hippos failed to come together and the hippos were never brought over. But let’s say some billionaire wants to do it today and establish them in unused swampland or backwater rivers.
They are apparently thriving in Columbia. Assuming you could somehow control them from wandering too far with Jurassic Park style fencing why could you raise them as a meat animal in controlled areas?
How many calories does it take to get a calorie of hippo meat? I believe chicken only requires 2 calories of feed to create 1 calorie of chicken meat. Cows are more like 7. No idea about pigs. I have no idea how long it would take a hippo to reach maturity or how many calories it would take.
If we bred hippos to be less aggressive, mature faster and have more muscle (and I’m sure taste better) maybe but I wouldn’t know what the math is for that. Hippos right now are aggressive dicks that take about 10 years to mature. They aren’t passive like cows. And I don’t know if they would accept living in a massive unrelated group.
I think re the energy in-out calculations there is the assumption that the hippos would be grazing on aquatic plants and would be placed where invasive plants have become an issue.
It’s difficult to get people into the habit of eating food - especially meat - that they didn’t grow up with. Bison has seen moderate success; ostrich & emu very little.
Some wild animals such as the African water buffalo and the zebra have proven resistant to domestication - meaning they stay wild and get on your ass if you annoy them. I have a feeling the hippopotamus is also in this group. They look like gentle giants but in fact regularly kill people.
Hippos could be used to help control excessive vegetation caused by farm run off water, harvesting excess animals could control the populations but they are very dangerous animals. I bet hippo milk would be good.
They are dangerous, but how many generations would it take to breed out the worst of the aggression? It might only take 5-10 generations, however that will take 30+ years if hippos take 6 or more years to reach sexual maturity. I assume hippos could be bred to be better livestock animals. More meat, faster maturity, less aggression, etc. However I don’t know if/when they would truly be non-threatening animals.