Sawyer Starrett, Graduate Student; Pedro Fernandes, Research Technician; Biquan Zhao, Post-doctoral Researcher; Yijie Xiong Assistant Professor, Animal Science; Mary Drewnoski Professor, Animal Science

Responsible faculty: Mary Drewnoski (mary.drewnoski@unl.edu)

Summary with Implications 

Strip grazing of stockpiled annual forages is known to improve carrying capacity compared to continuous grazing; however, optimal frequency of forage allocation in strip grazing remains unclear. Virtual fencing (VF) can reduce labor by eliminating the need for physical fence movements, but its effectiveness across grazing frequencies is not well defined. A late fall and winter oats grazing study was conducted using 72 crossbred steers to evaluate strip-grazing frequency with VF on carrying capacity and animal performance compared to continuous grazing. Treatments included continuous grazing, weekly strip grazing, and daily strip grazing. Weekly strip grazing increased carrying capacity by 42% and gain per acre by 35% compared to continuous grazing, but daily forage allocation did not further improve these responses. These results indicate that VF-enabled strip grazing can improve forage utilization and carrying capacity compared with continuous grazing. However, increasing forage allocation frequency beyond weekly did not provide additional benefits, suggesting that producers may be able to capture the benefits of strip grazing without daily forage allocations.

Introduction

Grazing annual forages is a viable alternative to late fall and winter hay feeding. Strip grazing has been shown to increase forage utilization and productivity (2024 Nebraska Beef Cattle report, pp.37-41) when grazing stockpiled annual forages. Strip grazing increases labor needs due to the need to put up and take down physical fences. With the market for virtual fence expanding, this technology decreases the labor needed to strip graze as there is no extra physical fence needed to be built and moved, but at a cost. Virtual fencing appears to be as effective as polywire in improving carrying capacity during strip grazing.   While strip grazing has demonstrated benefits, the optimal rate of movement to optimize forage utilization is unclear. Therefore, this study aimed to evaluate whether increasing frequency of forage allocation would result in further improvements in forage utilization and carrying capacity. 

Procedures

A fall/winter grazing study was conducted at the Eastern Nebraska Research and Extension Center (Mead, Nebraska). Seventy-two acres of late summer planted Jerry Oats (Avena sativa) were drilled on September 15^th, 2025, after corn silage was harvested. The field was sectioned into twelve, 6-acre paddocks and assigned randomly to 1 of 3 treatments: continuous grazing (CON), weekly strip grazing (WEK), and daily strip grazing (DLY), with 4 replications per treatment. 

The grazing study consisted of two phases. Phase 1 began on November 20, 2025, and continued for 72 days during which all three treatments grazed simultaneously. Phase 1 ended on January 31, 2026, when available forage was depleted in the CON paddocks, and all steers were removed from pasture. Because ungrazed forage remained in the DLY and WEK strip-grazed paddocks, steers assigned to these treatments returned to pasture on February 11, 2026, for an additional 19 days of grazing, designated as Phase 2.

Pre-grazing samples were collected prior to initiation of grazing to estimate initial forage mass. Post-grazing samples were collected at the end of Phase 1 to determine forage remaining following grazing. Samples were collected at a density of one sample per acre, resulting in six samples per paddock. Sampling locations were distributed across each paddock to capture spatial variability, with the technician rotating among paddocks to minimize sampler bias and ensure variation was evenly distributed across treatments. All samples were clipped to ground level within a defined sampling area of 5.6 ft², representing 36 inches of length cut from three rows of oats. Samples were dried at 140° F and used to estimate forage mass on a dry matter basis. Forage disappearance (lb DM/AUM) was calculated as the difference between pre- and post-grazing forage mass divided by carrying capacity achived (AUM/acre).

On November 1^st, 2025, prior to initiation of the trial, a pool of 76 candidate steers were fitted with virtual fencing collars (eSheperd^TM, Gallagher North America) and underwent a training period. Trained took place over a 12-day period in a 29-acre bromegrass pasture with a physical perimeter fence. During training a series of different sized virtual paddocks were used to acclimate animals to the virtual fencing system. Steers were then limit fed for 7 days, receiving a diet consisting of 50% alfalfa and 50% Sweet Bran (DM basis) at 2% BW. A total of 72 crossbred beef steers (initial BW 586 ± 1.7 lb) were then used in the experiment. Steers were stratified by BW and assigned randomly to paddock (6 head per paddock) based on the two-day, limit-fed weights at trial initiation. Water and a high calcium and magnesium mineral were provided ad libitum throughout the experiment. There was no protein or energy supplementation provided during the grazing study. 

For strip-grazed treatments (WEK and DLY), forage allocations were determined using visual assessment of residual forage remaining after grazing, with allocations targeted to allow a 2-inch stubble height. At grazing initiation, both WEK and DLY were provided an initial allocation designed to supply approximately one week of grazing. Thereafter, new forage was allocated every 7.18 ± 2.04 d for WEK and every 1.04 ± 0.34 d for DLY. Steers assigned to CON had access to their entire paddock throughout the grazing period.

During Phase 1, there were three days of severe winter weather which required hay feeding, where cattle did not graze the experimental paddocks. These days were included in gain (ADG) calculations but were excluded from the carrying capacity calculations. At the end of Phase 1 (the first 72 days), all steers were removed from paddocks. Removal of all treatments at this time allowed for a common endpoint, ensuring that subsequent comparisons among treatments were not confounded by differences in environmental conditions. Upon removal, all cattle were limit-fed for a total of 9 days to minimize variation in gut fill. Cattle were weighed on the final three consecutive days of this period. Strip-grazing treatments (DLY and WEK) utilized 4.35 and 4.22 acres, respectively, whereas the CON utilized the full 6-acre paddock, resulting in additional ungrazed forage remaining in the strip-grazing treatments after forage in the CON paddocks were depleted. On the final weighing day, steers assigned to the WEK and DLY treatments were returned to the oats pasture, whereas CON steers remained off pasture due to forage depletion. The strip-grazed treatments continued to receive new forage allocations for an additional 19 days, representing Phase 2 of the study. This period represents the additional grazing made possible by improved forage utilization in strip-grazing systems, providing a direct measure of increased carrying capacity relative to continuous grazing. 

Containment rate was calculated using GPS location data collected from the virtual fence collars and expressed as the percentage of GPS locations occurring within the assigned virtual fence boundary. Containment rate was used to evaluate the effectiveness of the virtual fencing system in keeping cattle within their assigned grazing area. Whole-period containment was calculated by combining GPS observations across all forage allocations, with approximately 52,000 to 56,000 GPS locations evaluated per pasture. A 9 ft buffer was applied to the virtual fence boundary to account for expected GPS positional error. Containment rate exceeded 98% for both DLY and WEK throughout the trial. The average number of auditory cues and electrical pulses was calculated on a per-steer, per-allocation basis for each strip-grazing treatment. The number of auditory cues and electrical pulses was used to evaluate steer interactions with the virtual fence and their responsiveness to the system. An audio ratio, calculated as the percentage of total cues that were auditory cues, was also determined to evaluate the extent to which cattle responded to auditory cues without requiring an electrical pulse. 

To characterize the forage allocations provided throughout the grazing period, the width of each new allocation was calculated as the linear distance (feet) between the previous virtual boundary and the newly established virtual boundary. This was done for each new allocation for DLY and WEK. Average forage allocation distance was 19 ± 7.87 ft for DLY and 80 ± 26.05 ft for WEK. In terms of acres this distance represented an average of 0.056 and 0.378 acres per allocation for DLY and WEK, respectively. Allocation distances ranged from 6 to 42 ft for DLY and 2 to 166 ft for WEK.

Performance, forage, paddock productivity, and virtual fence response data were analyzed as a completely randomized design using the MIXED procedure of SAS. Paddock served as the experimental unit, and treatment was included as the fixed effect. Phase 1, Phase 2, and Total (Phases 1 and 2 combined) were analyzed separately. Least squares means were separated using the PDIFF option of SAS. Differences were considered significant at P ≤ 0.05, and tendencies were declared at P > 0.05 and P ≤ 0.10.

Results 

Initial forage mass did not differ among treatments (P = 0.29; Table 1). However, at the end of Phase 1, after 72 days of grazing, ending forage mass was affected by treatment (P = 0.02). This resulted in CON leaving more residual forage (P ≤ 0.01) than both DLY and WEK, which were not different (P = 0.83). However, despite more residual, forage disappearance (lb DM/AUM) differed among treatments (P = 0.04), with CON having greater disappearance than DLY (P ≤ 0.01) and tending to have greater disappearance than WEK (P = 0.08), while DLY and WEK did not differ (P = 0.32; Table 1). Thus strip grazing has less forage disappearance to support an AUM, suggesting improved harvest efficiency compared with continuous grazing.

During Phase 1 (Table 2), ending BW tended to differ among treatments (P = 0.07), with CON cattle being 20 lb heavier than DLY (P = 0.02), while WEK was intermediate and did not differ from either CON (P = 0.27) or DLY (P = 0.16). However, average daily gain did not differ among treatments (P = 0.11). Despite similar ADG, gain per acre increased (P < 0.01) for strip-grazed treatments, with both DLY (P = 0.04) and WEK (P < 0.01) exceeding CON. Gain per acre of DLY and WEK did not differ (P = 0.13). The improvement in gain per acre is due to the greater harvest efficiency resulting in a smaller number of acres needing to be grazed by the strip treatments in Phase 1. 

In Phase 2 (Table 3), no differences (P > 0.17) were observed between DLY and WEK for any performance or productivity measures. Compared with Phase 1, ADG was numerically greater during Phase 2, while carrying capacity was numerically lower. Overall, strip grazing improved forage utilization, gain per acre, and carrying capacity without substantially impacting animal performance. Increasing allocation frequency from weekly to daily did not provide additional benefits, indicating that cattle were already utilizing available forage efficiently under a weekly strip-grazing system and that more frequent moves did not further reduce forage waste.

Across the entire grazing period, combining Phase 1 and Phase 2 (Table 4), ending BW was greater (P < 0.01) for WEK and DLY compared with CON while WEK tended (P = 0.09) to be greater than DLY. The greater BW of the strip treatments was due to the extra grazing days obtained compared to the CON. Average daily gain differed (P = 0.02), with CON being greater (P < 0.01) than DLY but not different (P = 0.12) from WEK. Average daily gain did not differ between DLY and WEK (P = 0.11). Carrying capacity (AUM/acre) differed (P < 0.01) among treatments, with WEK being greater than both CON (P < 0.01) and DLY (P = 0.04), and DLY greater (P < 0.01) than CON. Overall, strip grazing increased carrying capacity over CON by 46% and 53% for DLY and WEK, respectively. This increase in carrying capacity occurred without negatively affecting gain, suggesting strip grazing achieved better utilization without reducing intake. This likely occurred through reduced forage trampling losses. Overall, gain per acre differed (P < 0.01) among treatments, with WEK being greater than CON (P = 0.01) and DLY (P = 0.05), while DLY was greater (P = 0.04) than CON. While strip grazing did improve carrying capacity and gain per acre, contrary to popular belief these data suggest that daily allocation did not provide additional benefits over weekly allocation. 

Across the total grazing period, WEK maintained greater containment than DLY (99.53 vs. 98.50%; P = 0.02; Table 5). Overall, DLY received more audio cues (290.5 vs. 70.9 cues/steer/day; P < 0.01) and electrical pulses (9.13 vs. 1.63 pulses/steer/day; P < 0.01) than WEK, while audio ratio did not differ between treatments (96.9 vs. 98.0%; P = 0.15). Despite these differences, containment exceeded 98% for both strip-grazing treatments throughout the study, indicating that virtual fencing contained cattle within their assigned boundaries for the overwhelming majority of recorded GPS locations. The continuously grazed (CON) treatment was not included in the statistical analysis because fence failures were not independent among paddocks. 

Conclusion 

These results demonstrate that strip grazing stockpiled oats using virtual fencing can improve forage utilization and carrying capacity without reducing average daily gain. Virtual fencing effectively contained cattle within assigned grazing areas, with total containment exceeding 98% for both strip-grazing treatments. Increasing forage allocation frequency from weekly to daily did not further improve carrying capacity, indicating that weekly strip grazing may be sufficient to capture the productivity benefits of more intensive forage allocation without the need for daily moves.

Acknowledgment 

This project is supported by the United States Department of Agriculture grant 58-3040-1-013: Precision Livestock Management Systems for Western Rangelands.