Ideally, breeds that give a good feeds to weight conversion ratio should be fattened. Feed to weight conversion means the speed at which an animal turns feeds it has eaten into weight on the body. Such include breeds like borans or borans mixed with local indigenous cows, brahmans, Sahiwal mixed with indigenous breeds.
A boran can grow to 200kg after just 1 year of good feeding compared to an indigenous cow that may take 5 years to attain the same weight. The only challenge is that borans or mixed borans are slightly more expensive than the local breeds. If you are to fatten local breeds, go for young bulls of around 1-2 years because they gain weight faster than the cows.
The market can be the local slaughter market, there are many in Mbarara, Kiruhura, Ngoma, Kyankwanzi, Soroti and Kumi, among others, but in most cases, buyers directly pick the fattened bulls from the farm and take them for slaughter houses in Kampala or the nearest city.