The type of hay you should buy depends on location,climate,soil and the intended use of the hay.
The type of hay you should buy depends on location, climate, soil and the intended use of the hay. The hay you buy should grow in the general area. Climate is what generally determines the type of hay grown in the region. Soil conditions can cause a planter to sale a different type of hay than normal for the area.  This guide is intended to lead you, the livestoc or horse owner, in the right direction when selecting quality hays and grasses. We’ve also provided information that will assist you in growing your own hay. based on the area that you live in, different types of forages will be grown due to soil mae-up and climate. Silage is a fermented, high-moisture alternative that can be fed to cattle. It is made from grass crops including corn, sorghum or other cereals, using the entire green plant. Silage can be made from many field crops. The most common types are corn silage, alfalfa silage and grass silage. Cold winters and warm summers. Where winters are cold and summers warm, timothy (Phleum pratense) is the preferred hay grass and red clover or lucerne (according to soil) the main legume. Oats, sweet clovers (Melilotus spp.) and vetches can be grown. In arid areas, of course, all crops are grown under irrigation. Hay is a common crop in arid parts of Asia. Rainfed, sown hay in semi-arid areas is commonest on large farms, since yields are generally erratic through variations in rainfall. Lucerne can be grown on suitable soils. Most hay is grown in the cool season but, where moisture is available in summer, Sudan grass and fodder sorghums can be grown. Oat is a major hay crop, especially in North Africa, often for sale to transhumant flocks or for transport to the desert fringe, and it can be grown on most well-drained soils. In arid areas, of course, all crops are grown under irrigation. Hay is a common crop in arid parts of Asia. Rainfed, sown hay in semi-arid areas is commonest on large farms, since yields are generally erratic through variations in rainfall. Lucerne can be grown on suitable soils. Hay is basically dried vegetation: usually a legume such as alfalfa or clover, or a grass such as timothy or brome. It's one crop that can be raised with proper care in any part of the country where weeds will grow, and it's a must for any self-sufficient farmer who keeps livestock. — MOTHER.). Whatever hay crop you choose can be grown either as part of a farm rotation plan or in a permanent meadow. The former system has the advantage of helping establish uniform soil fertility (particularly if one of the legumes is raised). Alfalfa Seed Types. In the United States, farms grow alfalfa to use as hay for cattle and other livestock food. Alfalfa is a common forage crop that provides the livestock with the nutrition they need to thrive and grow. There are many types of alfalfa varieties offered by United States seed companies. 1 Affinity alfalfa can grow in a very cold climate and strong against root rot disease. 2  If this variety is cut very close to the ground, it can grow back for another harvest. 3  Affinity is also resistant to many varieties of insect’s pests that usually give other alfalfa seeds problems. A Guide to Growing, Harvesting and Baling Hay. The choice of plant (or plants) to be grown for hay depends on many factors: climate, availability of water, tonnage needed, type of livestock being fed, etc. Local preferences are usually a good guide. — MOTHER.). Whatever hay crop you choose can be grown either as part of a farm rotation plan or in a permanent meadow. The former system has the advantage of helping establish uniform soil fertility (particularly if one of the legumes is raised). Climate. Corn is a summer crop that is best grown in a climate that offers warm weather and long sun-filled days. Seedlings do not transplant well, so the best approach is to plant seeds directly into the soil. However, in areas where growing seasons are short, seeds can be started indoors using biodegradable pots Alfalfa is a cool-season perennial commonly grown for feeding livestock or as a cover crop and soil conditioner. Alfalfa is highly nutritious and a natural source of nitrogen. It’s ideal for improving the soil and providing erosion control. Alfalfa’s extensive root system nourishes both plants and soil.  A-Z Pests. Sprays. Beneficial Pests. Timothy is a versatile grass that can be fed to cattle and (especially) horses as hay, and also can provides suitable forage, usually in combination with a legume such as alfalfa, to sheep, cattle, goats and other animals. 
http://www2.latech.edu/~bmagee/303fal97/haypag.htm http://www.southernstates.com/docs/brochures/2012-hay-pasture-guide-web.pdf http://www.fao.org/docrep/005/X7660E/x7660e0c.htm http://www.fao.org/docrep/005/X7660E/x7660e0c.htm http://www.motherearthnews.com/homesteading-and-livestock/growing-harvesting-baling-hay-zmaz75jazgoe.aspx http://www.diy-guides.com/alfalfa-seed-types/ http://www.motherearthnews.com/homesteading-and-livestock/growing-harvesting-baling-hay-zmaz75jazgoe.aspx http://homeguides.sfgate.com/ideal-climate-soil-corn-growth-37426.html http://www.gardeningknowhow.com/edible/vegetables/alfalfa/growing-alfalfa.htm http://www.heirloom-organics.com/guide/va/guidetogrowingtimothygrass.html
what type of climate is hay grown in