PS8-22. Evaluation of Grazing or Harvesting Cereal Rye in Corn-soybean Rotation on Yield and Nutritive Quality.

Abstract The objective was to determine forage yield, quality and feed value of cover crops when either grazed or mechanically harvested in the spring. Four treatments were randomly assigned to 20 plots (5 plots/treatment) on an approximately 20-hectare field (1 ha/plot) in a corn/cereal rye/soybean rotation at the Dudley Smith Farm near Pana, IL. The treatments include: no cereal rye (CON), cereal rye – no graze or mechanically harvest (CC), cereal rye – grazed (CC-G), and cereal rye – mechanically harvested (CC-MH). Cereal rye was drilled at a rate of 100 kg/ha into corn stover in October 2024. Twenty fall-calving cows were stratified by initial body weight (BW; 663 ± 62 kg) and body condition score (BCS; 5.9 ± 0.56) and assigned to a CC-G plot (4 cows/plot). Cows grazed within their respective CC-G plots for 17 d (April 11th, 2025 to April 28th, 2025) and gained 2.35 kg/d. Cereal rye – mechanically harvested plots were cut on May 14th, 2025 and raked, baled, and wrapped the following day. Forage samples were collected on April 10th, 2025 and May 14th, 2025. A 0.25 m2 quadrat was tossed 3 times/plot and mechanically clipped to an above-ground stubble height of 7.62 cm to determine forage mass and nutritive quality. Data were analyzed utilizing the MIXED procedure of SAS 9.4. On April 10th, 2025, dry matter (DM) concentration was greater (P = 0.02) in CC-G plots than CC-MH with CC being intermediate (21.4, 19.6 and 20.4 %, respectively). There were no differences (P ≥ 0.44) between treatments in crude protein (CP), total digestible nutrients (TDN), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Macro- and micromineral concentrations were not different (P ≥ 0.20) between treatments. On April 10th, 2025, forage yield was not different (P = 0.69) between CC-G, CC-H, and CC-MH. On May 14th, 2025, DM concentration was not different (P = 0.11) between treatments. There was a tendency (P = 0.07) for CC-H and CC-MH to have greater concentrations of NDF compared to CC-G. Acid detergent fiber was greater (P = 0.01) in CC-H and CC-MH compared to CC-G. Crude protein and TDN concentrations were greater (P = 0.01) in CC-G compared to CC-H and CC-MH. Calcium, phosphorus, magnesium, iron, copper, zinc, aluminum, boron, and nitrogen concentrations were greater (P ≤ 0.03) in CC-G than CC-H and CC-MH. There were no differences (P ≥ 0.15) in potassium, sodium, and manganese concentrations. On May 14th, 2025, CC-H and CC-MH had greater (P = 0.01) forage yield compared to CC-G. The cereal rye remained in a vegetative state after grazing and at the time of mechanical harvest was higher quality compared to the mechanically harvested cereal rye which produced more tonnage.