Sheep Performance during Grazing of Annual Forages in a Double Cropping System

Abstract

Pasture for grazing animals is often in short supply during late summer in the North Central states. Our objective was to evaluate lamb (Ovis aries) performance on soybean [Glycine max (L.) Merr.], cowpea [Vigna unguiculata (L.) Walp], sudangrass [Sorghum bicolor (L.) Moench], and kochia [Kochia scoparia (L.) Schrad.] grown as the second crop in a double-cropping system following barley (Hordeum vulgare L.) harvested for forage. A controlled herbage allowance (mean availability of 4.8% of lamb body weight in terms of leaf-plus-flower tissue dry matter per day) was applied for 3 yr to the four annual forages in late summer on a Waukegan silt loam (fine-silty over sandy, mixed, mesic Typic Hapludoll). In addition, we compared the palatability to sheep of these four species with that of rape (Brassica napus L.), turnip (Brassica rapa L.), pearlmillet [Pennisetum americanum (L.) Leeke], and amaranth (Amaranthus emeritus L.). Soybean and cowpea resulted in average daily lamb gains (average of 0.44 lb/day) that exceeded those for sudangrass and kochia (average of 0.33 lb/d). In contrast, sudangrass and kochia had 78% greater lamb carrying capacity (d/acre) than soybean and cowpea. Liveweight gain per acre averaged 294,276,200, and 235 lb for sudangrass, kochia, soybean, and cowpea, respectively. Soybean and cowpea had greater nutritive value and leafiness than sudangrass and kochia but lower forage dry matter yields. Soybean and cowpea were consistently the most palatable forages while sudangrass, pearlmillet, and turnip were among the least palatable when lambs were not preconditioned to any of the forages. Kochia, amaranth, and rape were intermediate in palatability. Annual forages such as soybean, cowpea, kochia, or sudangrass can produce pasture that provides high daily gain, gain per acre, or carrying capacity when grown in a double-cropping system following a small grain harvested for forage.