Evaluation of Rotational Bale Grazing as an Alternative Winter-Hay Feeding System for Beef Cows

Traditional methods of winter hay feeding for beef cattle often entail numerous challenges, including high labor demands, high fuel consumption, soil compaction, limited nutrient dispersion, heightened nutrient runoff risks, low forage yields, and nitrogen loss from manure. Rotational bale grazing (RBG) offers an innovative approach to winter hay feeding by strategically positioning hay bales on pasture prior to the onset of winter feeding, then allowing controlled access to the bales. However, its feasibility in the temperate climate of the Southeastern U.S. remains uncertain. Therefore, this dissertation, conducted over two years at the Shenandoah Valley Agricultural Research and Extension Center in Raphine, VA, aimed to assess the feasibility of implementing RBG in Virginia. Three pre-established sacrifice paddocks (SP) and three five- paddock rotations for RBG treatments were utilized, with cattle being winter hay-fed for approximately 60 days. The study commenced with soil grid sampling across Novel Endophyte Tall Fescue (Schendonorous arundinaceous) pastures, strategically placing hay bales in areas with the lowest Mehlich 1- phosphorus (P). Changes in Mehlich 1-P, Mehlich 1-potassium (K), water-soluble P (WSP), nitrate (NO3-N), and pH were monitored over a two-year RBG implementation period. The results indicated that bale placement did not significantly alter the spatial distribution of Mehlich 1-P concentrations, but consistently influenced Mehlich 1-K distribution. The WSP concentrations remained consistent with bale placement but decreased without. Bale placement had no significant effect on NO3-N or pH.

Furthermore, this study investigated the effects of RBG on nutrient and sediment runoff in comparison to traditional SP. Artificial rainfall simulations were conducted on a SP, RBG first paddock grazed in the rotation (RBG first), and RBG last paddock grazed in the rotation (RBG last). The most significant differences were observed between the RBG first and last treatments, with forage presence in the RBG first paddock contributing to diminished runoff volume and nutrient load. Notably, the SP treatment showed no significant difference from the RBG treatment, likely due to many years of manure deposition increasing soil organic matter and water infiltration. The findings suggested that an RBG paddock grazed last in the rotation may lead to increased runoff volumes, sedimentation, and nutrient concentrations compared to an RBG paddock grazed first in the rotation. To understand the impact of RBG on forage biomass recovery, spring forage biomass was measured using ground manual samples and drone imagery. Manual samples and drone flights were conducted three times post-winter hay feeding. While the SP system exhibited the highest biomass recovery in high animal impact areas, RBG showed numerically higher biomass by the third sampling date in low animal impact areas. Drone imagery showcased potential for biomass estimation, but processing of drone images took excessive time and rendered it less feasible compared to manual samples.