Profitability of deer farming, as with other livestock operations is enhanced when adapted forages are utilized to meet as much of the nutrient requirements of the animal as possible. Feeding of protein, energy (grain), and mineral supplements is costly and requires additional labor and equipment. Supplementation, however, is still required when the nutrient levels of the available forage does not meet the animal's requirements.
The most prominent class of forages in the southeastern U.S. are the warm-season perennial grasses such as bermudagrass, bahiagrass, dallisgrass, switchgrass and Johnsongrass. They take advantage of the long growing season with maximum growth occurring between 80 and 90 degrees F. Unfortunately, they have the lowest digestibility.
Sod-type perennial grasses are best for deer because they tolerate close, selective grazing. Examples of warm-season annual grasses are sorghum-sudan hybrids. Tall fescue, orchardgrass and timothy are examples of cool-season perennial grasses in the upper south and northern U.S. Caution should be used with tall fescue because it usually contains an endophyte that reduces animal performance. Prominent cool-season annual grasses are annual ryegrass, rye, wheat, oats and barley. Their principal use in the southern U.S. is for young growing animals during the winter when warm-season perennial grasses are dormant. Alfalfa and clovers are the best known legumes. Alfalfa is a perennial while red and white clovers are considered shot-lived perennials. Annual covers such as arrowleaf and crimson play a major role in the southeastern U.S. where perennial legumes are not well adapted. Cowpea and soybeans are examples of summer annual legumes that are preferred by deer.
The nutritive value of forages is based on the nutritional level (energy, protein, etc.) and its availability to the digestive system of the animal. As percent digestible dry matter increases, animal performance in terms of weight gain, milk production, weaning weight, and conception rate increases. Legumes are more digestible and higher in protein, calcium and phosphorus than grasses. In general, cool-season grasses are more digestible than warm-season grasses and annuals are more digestible than perennials. Deer and elk prefer legumes over grasses because they are higher quality and resemble forbs because of their broad leaves.
Within each forage class, plant age is the major influence on forage nutritive value. Nutritive value is highest in new growth and decreases with plant maturity. One reason is that leaves are more digestible than stems and the percent of leaves decreases as the plants mature and become more stemy. The second reason is that cell contents are 98% digestible and include carbohydrates, protein, triglycerides, and glycolipids. Cell walls are composed of cellulose, hemicellulose and lignin but are only 45 to 75% digestible. As plants grow, the cell walls increase from 30% to 80% of the plant content, thus decreasing digestibility. A hay harvest schedule of 4 to 5 weeks is recommended for warm-season grasses as a good compromise between quality and yield.