My (naive) reasons for starting with cattle are:
I believe that certaiin breeds are hardy enough to stay out all winter and that they can feed on grass the whole year round. (I do understand they need some shelter, such as an open shed, and some winter feed, such as silage bails).
I keep pigs and find that I am buying in too much bag-food and this seems wasteful, considering I have land to spare. If there were true grass-feeding pigs, I might not bother with cattle.
In my innocence, I thougt that smaller cattle would be easier than large beasts. I am still open to persuasion.
My plan is to get two beasts in the spring, rear them and take them to slaugher in two years. If this is the beginning of something better, I will be delighted. I will continue with the pigs and the hens in any case.
Finally may I thank all the posters here who give me so much food for thought - you couldn't get such sound advice from a trailer-load of agricultural advisers.