Hi Denice, I've answered a similar question
in this thread, so I'll just provide the link, and a highlight below of part of
the answer most relevant to your situation.
Different plants will do best in different regions. Furthermore, it is about matching the right grass species to your particular grazing goals. Start by making a very clear farm plan for your cattle farm. The ideal hay mix is going to be different than a pasture mix for a summer grazing program, while a winter grazing program will benefit from adding yet other plants to the mix to provide plants that are strong to stand up through snow and are more resistant to leaching. And then go to your seed supplier to put together a mix that specifically caters to those needs. Also ask your neighbors what is thriving on their farms - and make sure you include lots of those species in your mix. No matter how wonderful a plant looks on paper, if it doesn't like your soil/climate/environment, it isn't going to be much use.