ABSTRACT
Corn (Zea mays) crops harvested as grain in autumn do not provide opportunity for cover crop establishment, which may be remedied by interseeding cover crops into growing corn. Grazing cover crops after corn grain harvest could provide added revenues and increase nutrient cycling in the system while providing additional ecosystem services. However, tradeoffs between cash crop productivity and cover crop inclusion, and use as grazed forage, are not fully understood. This 4-year Long-Term Agroecosystem Research Integrated Common Experiment project evaluated the effect of interseeding cereal rye (Secale cereale) into corn for grazing after corn grain harvest on corn grain yield and late-season grazing. Cereal rye was interseeded into corn in early June. After corn grain harvest, six paddocks at each location were randomly allotted to grazed (GRAZ) or not grazed (NG). The GRAZ paddocks were grazed with beef cattle in late autumn and again in early spring if regrowth allowed. Paddocks were flown with an unmanned aerial system (UAS) to characterize spatial forage yield and quality. Cereal rye provided an additional 20-30 grazing days in the autumn for 24 beef cows on 4.8 ha. Early spring growth shows potential to provide even greater forage yields than autumn, but growth is less dependable. Corn grain yields did not decrease except in 2019 (dry year) when yields were 40% lower. There were no significant differences in soil health indicators between GRAZ and NG paddocks. The UAS shows promise as a tool for monitoring forage yield and quality and optimizing grazing management.
ABSTRACT
BACKGROUND: Integration of behavioral observations with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems. Brahman-influenced (BR; n = 64) and Gelbvieh × Angus (GA; n = 64) heifers consumed either toxic endophyte-infected tall fescue (E+) or one of two nontoxic endophyte-infected tall fescue (NT) cultivars during two yr. Heifers were weighed at midpoint and termination of grazing. Grazing behavior (grazing, resting in the shade, lying, or standing without grazing) was recorded (n = 13 visual observations per yr in June and July) for each pasture. During yr 2, exit velocity (EV) and serum prolactin (PRL) were determined. RESULTS: Grazing behavior was influenced (P < 0.05) by an interaction between fescue cultivar and breed type. Gelbvieh × Angus heifers assigned to E+ pastures had the lowest percentage of animals grazing and the largest percentage of animals resting in the shade. Brahman-influenced heifers had faster EV (P < 0.001) than GA heifers (0.52 vs. 0.74 ± 0.04 s/m, respectively). Body weight (BW) was affected (P < 0.01) by an interaction of tall fescue cultivar and d, and an interaction of tall fescue cultivar and breed type. Heifers grazing NT pastures were heavier (P < 0.01) than heifers grazing E+ pastures at midpoint and termination. Gelbvieh × Angus heifers grazing NT pastures were heavier (P < 0.01) than GA and BR heifers grazing E+ and BR heifers grazing NT pastures. An interaction of forage cultivar and breed type occurred on serum PRL (P < 0.01). CONCLUSION: Collectively fescue cultivar, EV, and concentrations of serum PRL were associated with grazing behavior. Heifers grazing NT pastures were observed to be grazing more than heifers assigned to E+ pastures, regardless of breed type, which may have contributed to changes in BW and average daily gain (ADG) in heifers. Integration of behavioral observations along with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems.
