Mob & rotational grazing in the northeast: diversity, yield, and quality implications

Authors: Billman, Eric; WILLIAMSON, JESSICA - Pennsylvania State University; Soder, Kathy; Andreen, Danielle (elle)

Submitted to: Northeast Pasture Consortium Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/10/2020
Publication Date: 1/19/2020
Citation: Billman, E.D., Williamson, J.A., Soder, K.J., Andreen, D.M. 2020. Mob & rotational grazing in the northeast: diversity, yield, and quality implications[Abstract]. Northeast Pasture Consortium Annual Meeting Proceedings. p. 1.

Interpretive Summary: No Interpretive Summary is required for this Abstract Only. JLB.

Technical Abstract: Introduction of novel grazing management systems has the potential to significantly alter pasture species composition, productivity, and forage quality. This is due to forage crops that may not be adapted or well-suited to increased or reduced grazing frequency and intensity. Mob grazing, a system developed in the western United States, has been rising in popularity over recent years, but has yet to be assessed for forage production systems in the Northeast. The objective of this research was to compare changes in species diversity, yield, and forage quality between a mob grazing system (MOB) and a traditional rotational grazing system (ROT) for the region. Eight, 0.10-ha plots were established in 2014 as a randomized complete block with four replications, and seeded with alfalfa (Medicago sativa L.), white clover (Trifolium repens L.), orchard grass (Dactylis glomerata L.), narrowleaf plantain (Plantago lanceolate L.), and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort]. Mob-grazed (MOB) plots were grazed twice year-1, (70 – 90-day interval), and rotationally-grazed (ROT) plots were grazed four to six times year-1, (when sward height reached 25 cm). At the conclusion of four years, alfalfa stands were 30% greater (P < 0.01) under MOB than ROT, and forage grass stands were 10 - 60% greater (P < 0.01) under ROT, depending on species. The different management systems also resulted in significantly greater yield (P < 0.01) in the MOB systems at individual harvests, but greater cumulative annual yield under ROT. Finally, forage fiber quality was less desirable under MOB grazing, with greater (P < 0.01) ADF and lignin concentrations. These results suggest that ROT may be more well-suited for northeastern grazing systems, as it provides a benefit to forage quality and cumulative yield per year, but that MOB grazing may be more desirable if the larger per-harvest biomass can be efficiently used by livestock.