ABSTRACT
Summary When they are properly fertilized, western Oregon dryland pastures of subterranean clover with grasses such as perennial ryegrass, tall fescue, and resident annuals produce total annual dry-matter yields averaging 6,500 kg/ha. Some sites are capable of over 9,000 kg/ha. Optimum use of this forage is complicated by its highly seasonal availability. Over 50% of the total growth occurs from late April to mid-June. Only about 10% takes place during autumn-early winter, and virtually none occurs during summer. Research shows livestock weight gains from 300 to over 700 kg/ha can be expected depending upon pasture mixture and kind of grazing use. Yearling cattle make the most efficient use of rapid spring growth. As grazing season lengthens, total animal production declines both because nutritive value declines and because old forage must be present for use during the summer dry and autumn-winter wet periods. Four major livestock production programs are used: (1) sheep (winter lambing), (2) beef cows calved in autumn, (3) cows calved in spring, and (4) purchased calves or yearlings. Hay cut from excess spring growth is usually fed during winter except in some coastal locations where appreciable winter plant growth occurs. By utilizing known characteristics of forage production and animal requirements, forage demand curves were developed. Yearlings stocked at 6-7.5/ha from mid-March to late June make highest weight gains/unit area as compared with cows-calves and ewes-lambs. Animal performance of about 100 kg/head or 730 kg/ha is possible on subclover-tall fescue in the Willamette Valley. Shorter duration of adequate forage quality with clover-ryegrass yields about 560 kg/ha. Pastures are capable of sustaining 10 ewes/ha, but few operators stock that heavily. Production of lamb/ha on clover-ryegrass pastures can be similar to that by yearling steers; but on clover-tall fescue or clover and other coarse grass, it will be less. Sheep do not consume coarse grasses such as tall fescue as well as cattle. Calf production from cows calved in spring is the most common form of beef operation. But autumn-bora calves and their dams make more use of spring forage than spring cow-calf pairs. From 27 to 45 kg more weaning weight can be expected. Wintering costs for this autumn cow-calf pair are an estimated $10-$35/head more. From a comprehensive management standpoint, ewes and lambs with either some purchased yearling cattle or autumn-calved cows appear to yield the most product from dryland and clover-grass pastures.
