Management Systems That Increase Uniformity of the Forage Supply for Year-round Grazing by Spring Calving Herds

A comparison was made between two different systems: a year-round grazing system and a minimal-land grazing system at the McNay Research Farm, Chariton IA. The winter component of a year-round grazing system used sequential grazing of corn crop residues and stockpiled grass legume forages. The winter component of a minimal land system consisted of cows maintaining in drylot. Following grain harvest, four 7.5-acre fields containing corn crop residues were stocked with cows at midgestation at an allowance of 1.5 acres per cow. After 2 months, cows in the year-round grazing system grazed stockpiled tall fescue-red clover or smooth bromegrass-red clover forage at 3 acres/cow for approximately 4 months. Forage organic yields at the initiation of grazing were 3,467 lb./acre for three years on corn crop reside fields and 2,473 and 1,968 for stockpiled tall fescue-red clover and smooth bromegrass-red clover fields. In all years, no seasonal differences in body weight or body condition scores were observed between cows sequentially grazing corn crop residues and stockpiled forage or cows maintained in drylot during winter. Grazing cows consumed less hay resulting in a 3-year average hay excess of 4,235 and 4,743 pounds of hay dry matter per cow in the yearround grazing systems while the minimal land system was deficient in hay by 4,529 pounds of hay dry mater per cow. The summer component of a year-round grazing system involved rotational stocking of smooth bromegrassorchardgrass- birdsfoot trefoil pastures with cow-calf pairs and stocker yearlings at .75 animal units/acre for 40 days, and hay harvest and grazing of tall fescue-red clover and smooth bromegrass-red clover pastures at .33 cow-calf pairs/acre for 57 days and 83 days grazing of smooth bromegrass-orchardgrass-birdsfoot trefoil pastures at .5 cow-calf units per are. The minimal land system involved the rotational stocking of smooth bromegrass-orchardgrass-birdsfoot trefoil pastures with cow-calf pairs grazing at .64 animal units/acre and hay removal from 40% of the pasture. Grazing system did not affect cow body weight, condition score, or calf daily gain in any of the three years. Growing animal production was affected by grazing system; the minimal land system 3-year average was 181 lb./acre compared with year-round system averages of 128.7 and 123.9 lb./acre. The year-round grazing systems also produced more net winter forage than did the minimal land system. Differences in forage quality were only observed between tall fescue-red clover, smooth bromegrass-red clover and smooth bromegrassorchardgrass- birdsfoot trefoil pastures during summer