Use of forages can lower costs of grain and protein supplementation. In the case of pasture systems, equipment and building costs decrease, resulting in lower fixed costs of production (PIH-13). If sows are bred in the late spring to farrow early fall, good quality forage can replace up to 50% of grain and supplement needs. One acre of good pasture can accommodate up to 8 sows for a season. During other seasons of the year, however, forage quality and availability will vary, and supplementation with corn and protein supplement will need to adjust to provide the necessary nutrients.
Available recommendations on stocking rates for grow-finish hogs on pasture vary considerably with soil fertility, pasture species, rainfall, and season impacting forage availability and quality. Available recommendations for pigs weighing less than 100 pounds are 1530 pigs per acre and 1020 pigs per acre for pigs weighing over 100 pounds. These numbers can be increased significantly with more intensive management such as rotational grazing. Grow-finish pigs on pasture are full-fed in most instances. However, some observations suggest limit feeding can be practiced with sufficient nutrient contributions coming from the pasture. Research focusing on the nutritional contributions of pasture with current swine genetics and management is limited.
A sample pasture mix might consist of seedings for permanent, rotational, or annual pastures. The permanent pasture might contain seedings of bluegrass, white clover, orchardgrass, and alfalfa. The rotational pasture may include alfalfa, red clover, ladino clover, sweetclover, alsike clover, orchardgrass, bromegrass, and Timothy grass. An annual or temporary pasture could be made up of brassicas, rape, soybeans, cowpeas, fababeans, sudangrass, rye, oats, wheat, barley, field peas, and mixes of grass and legumes (Zeller, 1948). Example diets that have been presented do not assume pasture supplementation due to the wide variation in forage or pasture types used, and will therefore need to be adjusted based on nutrients provided from the pasture.
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