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After small grains are harvested as hay, grain, or silage in many irrigated areas it is possible to produce a second crop. Brassica species and radish (Raphanus sativus L.) establish quickly and produce high-quality fall and winter forage. Recently, nematode-resistant radish cultivars (trap crops) have become available and studies show that they are an effective alternative to nematicides for control of the sugarbeet nematode (SBN, Heterodera schachtii Schmidt). A 2-yr study was conducted to determine the potential of allowing lambs (Ovis aries) to graze nematode-resistant radish. At Powell, WY, 'Adagio' trap-crop radish and 'Purple top' forage turnip (Brassica rapa L.) were grown in a replicated and randomized complete block design. Studies lasted 10 wk in 1994 and 12 wk in 1995. Lambs either grazed radish or turnip (a host of the SBN) continuously or they grazed radish and turnip, then were transferred to a feedlot diet. Additional groups of lambs received the feedlot diet for the entire study period. At Manderson, WY, 50 lambs were assigned to each replicate of radish for a 20-d period in 1994. SBN-resistant radish was comparable to SBN-susceptible turnip in forage production, quality, and acceptability and weight gain by fall-grazing lambs. Lambs grazing radish and turnip, without concentrate, produced acceptable market size and carcass grade; but they required longer than feedlot lambs to reach similar weight. Grazing of trap-crop radish shows promise for recovering expenses of growing the crop, providing further incentive for including this crop in sugarbeet (Beta vulgaris L.) rotations. |
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